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Alcohol inhalation
From Wikipedia, the free encyclopedia
Alcohol inhalation is a method of administering alcohol (also known as ethanol) directly into the respiratory system, with aid of a vaporizing or nebulizing device. It is chiefly applied for recreational use, when it is also referred to as alcohol smoking, but it has medical applications for testing on laboratory rats and treatment of pulmonary edema and Coronavirus in humans.
Recreational use[edit]To inhale alcohol, it must be first converted from liquid into gaseous state (vapor) or aerosol (mist). For recreational use, a variety of methods have been invented. Alcohol can be vaporized by pouring it over dry ice in a narrow container and inhaling with a straw. Another method is to pour alcohol in a corked bottle with a pipe, and then use a bicycle pump to make a spray. Alcohol can be vaporized using a simple container and open-flame heater.[1] Medical devices such as asthma nebulizers and inhalers were also reported as means of application.[2]
The practice gained popularity in 2004, with marketing of the device dubbed AWOL (Alcohol without liquid), a play on the military term AWOL (Absent Without Leave).[3] AWOL, created by British businessman Dominic Simler,[3] was first introduced in Asia and Europe, and then in United States in August 2004. AWOL was used by nightclubs, at gatherings and parties, and it garnered attraction as a novelty, as people 'enjoyed passing it around in a group'.[4]
AWOL was gimmicked as an alcohol "vaporizer", implying that it would heat the liquid until it entered a gaseous state, but is in fact a nebulizer, a machine that agitates the liquid into an aerosol. AWOL's official website states that "AWOL and AWOL 1 are powered by Electrical Air Compressors while AWOL 2 and AWOL 3 are powered by electrical oxygen generators",[5] which refer to a couple of mechanisms used by the nebulizer drug delivery device for inhalation. Although the AWOL machine is marketed as having no downsides, such as the lack of calories or hangovers, Amanda Shaffer of Slate describes these claims as "dubious at best".[3] Although inhaled alcohol does reduce the caloric content, the savings are minimal.[6]
After expressed safety and health concerns, sale or use of AWOL machines was banned in a number of American states.[7] The AWOL device was later followed by new products for alcohol inhalation, such as "Vaportini", created in 2009, which uses simple thermal vaporization.[8]
Effects and health concerns
There are possible health and safety risks of inhaling alcohol vapor. Inhalation devices make it "substantially easier to overdose on alcohol" than drinking, because the alcohol bypasses the stomach and liver and goes directly into the bloodstream, and because the user does not have a reliable way of determining how much alcohol they have taken in. Inhaled alcohol cannot be purged from the body by vomiting, which is the body's main protection against alcohol poisoning. Inhaled alcohol can dry out nasal passages and make them more susceptible to infection.[9] There is also a potential increased risk of addiction.[1][3]
Medical applications
Inhalation of vapor obtained by nebulization of water and ethanol in oxygen has been used in treatment of pulmonary edema in humans.[10] Alcohol vapor acts as an anti-foaming agent in the lungs, so the sputum becomes more liquid, and can be easily expelled. The method has also been used to reduce the alcohol withdrawal syndrome in patients who had intestinal tract surgeries.[11] The use of ethanol vapor has also been proposed as a potential method of inactivating respiratory viruses, such as SARS-CoV-2, which are present in the respiratory tract, [12], although there is no evidence that this practice is safe or effective.
Regulation
The examples and perspective in this section may not represent a worldwide view of the subject. You may improve this section, discuss the issue on the talk page, or create a new section, as appropriate. (April 2014) (Learn how and when to remove this template message)In the United States, many state legislatures have banned alcohol inhalation machines.[7] Support for such legislation comes from groups fighting underage drinking and drunk driving, including alcohol companies such as Diageo[13] and industry groups such as the Distilled Spirits Council of the United States (DISCUS), among others.
See also
References
Further reading
Structural Biochemistry/Alcohol< Structural Biochemistry
Definition
Ethanol Lewis (Picture)
Alcohol is a psychoactive drug/beverage. It is the second most used psychoactive drug. (Caffeine is rated as the first most used.) It is considered a depressant because at medium to high concentrations, it depresses neural firing. (Though at low levels, it can have the opposite effect.)[6] It contains no vitamin or minerals. However, it does contain calories. An important thing to note is that this type of alcohol should not be generalized to mean the same as the organic chemistry term alcohol. Rather this type of alcohol, in terms of organic chemistry, is actually ethanol (or ethyl alcohol). It's chemical formula is: CH3CH2OH.
Due to its small and amphiphilic nature, ethanol is soluble in water and fat, so it is able to cross cell membranes, giving it great access to do harm to cells and affecting the entire body.[6]
History
By the tenth-century, a Persian alchemist named al-Razi discovered the first alcohol. Today this alcohol is known as ethyl alcohol. Originally, the name kuhl or kohl was given to the very fine powder that was produced through a sublimation of the natural mineral stibnite to form a compound called antimony sulfide. Today, this product is used as eyeliner and cosmetic.
In the 16th century, the word "alcohol" appears in English that means a very fine powder. In his 1657 Lexicon Chymicum, William Johnson conveys the word as antimonium sive stibium. Through time, the word came to mean any fluid obtained through a process of distillation. This type of fluid includes that of alcohol of wine. In the year 1594, Libavius in Alchymia referred to alcohol as vini alcohol vel cinum alcalisatum. This word in the end was found to mean as "spirit of wine". Until the 18th century "spirit of wine" is referred to as ethanol, and was expanded to be called as "alcohols" in the world of today.
Absorption and Distribution through the body
Unlike other drugs, ethanol does not require digestion. The body can quickly absorb it into the system. Roughly 1/5 of the alcohol is absorbed directly through the walls the stomach. Next, the upper portion of the empty stomach absorbs it. Alcohol can also be absorbed through the lungs. Within 30-90 minutes, the body is able to reach the maximal blood concentration from the alcoholic beverage.
Blood Alcohol Content
Blood alcohol content (or commonly abbreviated BAC) is a measurement of the amount of alcohol in a person's blood. More specifically, it a measure of how many grams of alcohol in 100 milliliters of a person's blood. For example, if a person registers a .20 BAC, there is 1/5th of a gram of alcohol in every 100 milliliters of that person's blood.
Zero Order Kinetics (Elimination of Alcohol from the body)
Alcohol is mainly eliminated from the body through the metabolism. This occurs mainly from the liver. A small percent (5-10%) is eliminated directly through urine and breathing. Elimination of alcohol is considered Zero Order Kinetics. This means that the amount of alcohol removed is constant over time and does not depend on the concentration intake. This is unlike many other drugs that have half-lives and depend on the amount in the body. Alcohol is constantly eliminated over time. The liver can eliminate roughly .25 ounces per hour. It takes approximately two hours to completely eliminate one (Standard) drink.
Addiction
Alcohol increases the release of dopamine in the nucleus accumbens. Dopamine is responsible for movement, attention, learning, mood, etc. Dopamine also takes a part in the positive reinforcement (reward) system of the brain. It also triggers the release of endogenous opioids. Opiate receptors also seem to be involved in the reward system of the brain. Withdrawal effects are very powerful, (i.e. seizures, increased sensitivity of NMDA receptors). Alcohol's neurological influence on the reward system of the brain is what's primarily responsible for a person's physiological addiction to alcohol.
Toxic
Since the prehistoric times, a compound known as ethanol that is commonly seen in alcoholic beverages has been consumed by human beings for many centuries. The reason for this intake is due to dietary, hygienic, medicinal, religious, and recreational reasons (special event taken place in life). The idea of intoxication is the taking in large doses of ethanol that cause drunkenness. Drunkenness that is often seen when people drink heavily can lead to a hangover as its effect wears off after a period of time. It is important to know that ethanol can cause serious respiratory failure or even death depending on how much an individual take in to their body.
Primary and secondary metabolite, acetaldehyde, and acetic acid all cause the toxicity of ethanol. It is said that all primary alcohols are broken down into aldehydes. After that it is broken down to carboxylic acids which have toxicities that is similar to that of acetic acid and acetaldehyde. Metabolite toxicity is reduced in rats that are fed with acetic acid such as thiamine.
In addition, some secondary and tertiary alcohols are not as poisonous as they are known for. In other words, these alcohols are less poisonous than that of ethanol because the liver is unable to metabolize them into these toxic by-products. Therefore, they are better for medicinal and recreational use. A good example of a tertiary alcohol would be Ethchlorvynol. Ethchlorvynol is use for both medicinal and recreational use.
However, there are also many other alcohols that are more poisonous than that of ethanol. The reason for this is because these alcohols take a longer time to metabolize and their substance that they produce is even more toxic than ethanol. A type of wood alcohol is methanol. Methanol is oxidized to formaldehyde and then through formaldehyde dehydrogenase and alcohol dehydrogenase enzymes to the poisonous formic acid in the liver. The bad thing about this is that, this can cause blindness or even death. Administer ethanol is a great way to prevent toxicity after ingestion such as ethylene glycol or methanol. Although methanol is seen as poisonous, it has a much weaker sedative effect than that of ethanol.
Typically, long chain such as isopropanol, n-butanol or n-propanol have strong sedative effects. Their toxicity is also much higher than that of ethanol. These long chains are also known as fusel alcohols and are surprisingly found to be contaiminanting to certain alcoholic beverages. Thus, this is the reason why people who drink excess or large amount of alcoholic beverage will encounter a kind of hangover. Overall, many of these long chain and even longer chains are used in the industry today as a kind of solvent and are used in alcohol that causes all kinds of serious health conditions.
Withdrawal
After a cycle of addiction, withdrawal may come after if the amount of alcohol intake is decreased or stopped. Withdrawal symptoms generally occur 24-48 hours after stoppage of intake. It can lead to symptoms that include insomnia, hyper excitability, and tremors. Furthermore, it can lead to changes in the sympathetic system that include: increased heart rate, increased blood pressure, and increased body temperature. After these early withdrawal symptoms occur, later symptoms (usually 2-4 days after) can occur. These include fits of delirium tremors, hallucinations, and high fevers. Aside from physical changes, alcohol withdrawal can lead to anxiety and dysphoria (negative mood state). One of the main treatments for withdrawal is a Benzodiazepine drug called Chlorodiazepozide(Librium). It is a sedative/hypnotic drug that helps to counteract the affects of alcohol withdrawal.
Blood Alcohol Content
Blood alcohol content (or commonly abbreviated BAC) is a measurement of the amount of alcohol in a person's blood. More specifically, it a measure of how many grams of alcohol in 100 milliliters of a person's blood. For example, if a person registers a .20 BAC, there is 1/5th of a gram of alcohol in every 100 milliliters of that person's blood.
Zero Order Kinetics (Elimination of Alcohol from the body)
Alcohol is mainly eliminated from the body through the metabolism. This occurs mainly from the liver. A small percent (5-10%) is eliminated directly through urine and breathing. Elimination of alcohol is considered Zero Order Kinetics. This means that the amount of alcohol removed is constant over time and does not depend on the concentration intake. This is unlike many other drugs that have half-lives and depend on the amount in the body. Alcohol is constantly eliminated over time. The liver can eliminate roughly .25 ounces per hour. It takes approximately two hours to completely eliminate one (Standard) drink.
General Effects
Alcohol causes a loss of inhibition and judgment, which can lead to aggressive behavior. Alcohol also causes impairment of the senses and can lead to liver and heart problems.
Neurological Effects
Alcohol interferes with neural adhesion protein-protein that helps to guide growth of neurons in developing brain. Alcohol is an agonist of GABA receptors and antagonist of NMDA receptors. The GABA (gamma-aminobutyric acid) neurotransmitter is responsible for inhibition in the brain and GABA receptors activate chloride ion channels. Glutamate is the normal neurotransmitter for the NMDA receptors, but NMDA can also activate these receptors in a similar manner. However, NMDA does not bind to other glutamate receptors. NMDA is an excitatory neurotransmitter that is responsible for learning and memory. NMDA receptors activate ion channels that allow the influx of sodium and calcium ions.
Diseases
Some diseases associated with drinking alcohol are Korsakoff’s Syndrome and Fetal Alcohol Syndrome. Korsakoff’s Syndrome is characterized by a deficiency in thiamine (Vitamin B1), which leads to damage in the mammillary bodies in the hypothalamus and hippocampus.
Fetal alcohol syndrome is caused when a woman drinks alcohol during pregnancy and the alcohol impairs the baby’s development. Two traits that are common in babies with fetal alcohol syndrome physical deformity and mental retardation. It causes mild to moderate retardation. It can also lead to hyperactivity in childhood as well as growth deficiency. This syndrome is also has characteristic facial abnormalities. Ethanol's affects on fetal development include, but are not limited to, disruption of production of cell-adhesion molecules, druption of normal apoptosis (programmed cell death), and disruption of neurotrophic support.[6]
Alcohol Dehydrogenase
Alcohol dehydrogenase is the primary enzyme that converts alcohol into acetaldehyde. This enzyme is part of the primary metabolic system for alcohol. The activity of alcohol dehydrogenase determines the rate of alcohol metabolism. Therefore, myths such as exercise or coffee consumption do not play a role in speeding up the metabolism system. [5]
Having a deficiency in alcohol dehydrogenase decreases the speed of the metabolic process, therefore taking longer to break down alcohol. There is evidence that women have less alcohol dehydrogenase enzymes than men. There has been some evidence that fluctuations in women's menstrual cycles, gonadal hormone levels can influence the rate of their alcohol metabolic system. Women may have elevated blood alcohol concentrations at different times throught their cycle.[7]
Acetaldehyde Dehydrogenase
Ethanol to acetaldehyde (Picture)
Acetaldehyde dehydrogenase reaction (Picture)
Acetaldehyde Dehydrogenase (ALDH) are dehydrogenase enzymes that help convert acetyldehyde into acetic acid. More specifically, this enzyme is present in the metabolism and helps to break down alcohol. When a person drinks, the alcohol is first converted to acetaldehyde by the alcohol dehydrogenase enzyme. Acetaldehyde dehydrogenase is needed to further break the new acetyldehyde into more harmless acetic acid.
If an individual has a deficiency in acetaldehyde dehydrogenase, this breakdown cannot occur, leading to elevated acetaldehyde levels which results in vomiting, hyperventilation, nausea, increased heart rate, and alcohol flush reaction. It has been found that people of East Asian descent usually have genes that code for an inactive variant of acetaldehyde dehydrogenase 2.[2]
References[edit]
Ethanol metabolism
From Wikipedia, the free encyclopedia
Ethanol, an alcohol found in nature and in alcoholic drinks, is metabolized through a complex catabolic metabolic pathway. In humans, several enzymes are involved in processing ethanol first into acetaldehyde and further into acetic acid and acetyl-CoA. Once acetyl-CoA is formed, it becomes a substrate for the citric acid cycle ultimately producing cellular energy and releasing water and carbon dioxide. Due to differences in enzyme presence and availability, human adults and fetuses process ethanol through different pathways. Gene variation in these enzymes can lead to variation in catalytic efficiency between individuals. The liver is the major organ that metabolizes ethanol due to its high concentration of these enzymes.
Human metabolic physiology
Ethanol and evolution
The average human digestive system produces approximately 3 g of ethanol per day through fermentation of its contents.[1] Catabolic degradation of ethanol is thus essential to life, not only of humans, but of all known organisms. Certain amino acid sequences in the enzymes used to oxidize ethanol are conserved (unchanged) going back to the last common ancestor over 3.5 bya.[2] Such a function is necessary because all organisms produce alcohol in small amounts by several pathways, primarily through fatty acid synthesis,[3] glycerolipid metabolism,[4] and bile acid biosynthesis pathways.[5] If the body had no mechanism for catabolizing the alcohols, they would build up in the body and become toxic. This could be an evolutionary rationale for alcohol catabolism also by sulfotransferase.
Physiologic structures
A basic organizing theme in biological systems is that increasing complexity in specialized tissues and organs, allows for greater specificity of function. This occurs for the processing of ethanol in the human body. The enzymes required for the oxidation reactions are confined to certain tissues. In particular, much higher concentration of such enzymes are found in the liver,[6] which is the primary site for alcohol catabolism. Variations in genes influence alcohol metabolism and drinking behavior.[7]
Thermodynamic considerations
Energy thermodynamics
Energy calculations
The reaction from ethanol to carbon dioxide and water is a complex one that proceeds in three steps. Below, the Gibbs free energy of formation for each step is shown with ΔGf values given in the CRC.[8]
Complete reaction:
C2H6O(ethanol) → C2H4O(acetaldehyde) → C2H4O2(acetic acid) → acetyl-CoA → 3H2O + 2CO2.
ΔGf = Σ ΔGfp − ΔGfo
Step one
C2H6O(ethanol) + NAD+ → C2H4O(acetaldehyde) + NADH + H+
Ethanol: −174.8 kJ/mol
Acetaldehyde: −127.6 kJ/mol
ΔGf1 = −127.6 kJ/mol + 174.8 kJ/mol = 47.2 kJ/mol (endergonic)
ΣΔGf = 47.2 kJ/mol (endergonic, but this does not take into consideration the simultaneous reduction of NAD+.)
Step two
C2H4O(acetaldehyde) + NAD+ + H2O → C2H4O2(acetic acid) + NADH + H+
Acetaldehyde: −127.6 kJ/mol
Acetic acid: −389.9 kJ/mol
ΔGf2 = −389.9 kJ/mol + 127.6 kJ/mol = −262.3 kJ/mol (exergonic)
ΣΔGf = −262.3 kJ/mol + 47.2 kJ/mol = −215.1 kJ/mol (exergonic, but again this does not take into consideration the reduction of NAD+.)
Step three
C2H4O2(acetic acid) + CoA + ATP → Acetyl-CoA + AMP + PPi
(Because the Gibbs energy is a state function, we skip the formation of Acetyl-CoA (step 3), for lack of thermodynamic values.)For the oxidation of acetic acid we have:
Acetic acid: −389.9 kJ/mol
3H2O + 2CO2: −1500.1 kJ/mol
ΔGf4 = −1500 kJ/mol + 389.6 kJ/mol = −1110.5 kJ/mol (exergonic)
ΣΔGf = −1110.5 kJ/mol − 215.1 kJ/mol = −1325.6 kJ/mol (exergonic)
Discussion of calculations
If catabolism of alcohol goes all the way to completion, then, we have a very exothermic event yielding some 1325 kJ/mol of energy. If the reaction stops part way through the metabolic pathways, which happens because acetic acid is excreted in the urine after drinking, then not nearly as much energy can be derived from alcohol, indeed, only 215.1 kJ/mol. At the very least, the theoretical limits on energy yield are determined to be −215.1 kJ/mol to −1325.6 kJ/mol. It is also important to note that step 1 on this reaction is endothermic, requiring 47.2 kJ/mol of alcohol, or about 3 molecules of adenosine triphosphate (ATP) per molecule of ethanol.
Organic reaction scheme
Steps of the reaction
The first three steps of the reaction pathways lead from ethanol to acetaldehyde to acetic acid to acetyl-CoA. Once acetyl-CoA is formed, it is free to enter directly into the citric acid cycle. However, under alcoholic conditions, the citric acid cycle has been stalled by the oversupply of NADH derived from ethanol oxidation. The resulting backup of acetate shifts the reaction equilibrium for acetaldehyde dehydrogenase back towards acetaldehyde. Acetaldehyde subsequently accumulates and begins to form covalent bonds with cellular macromolecules, forming toxic adducts that, eventually, lead to death of the cell. This same excess of NADH from ethanol oxidation causes the liver to move away from fatty acid oxidation, which produces NADH, towards fatty acid synthesis, which consumes NADH. This consequent lipogenesis is believed to at least largely underlie the pathogenesis of alcoholic fatty liver disease.
Gene expression and ethanol metabolism
Ethanol to acetaldehyde in human adults[edit]In human adults, ethanol is oxidized to acetaldehyde using NAD+, mainly via the hepatic enzyme alcohol dehydrogenase IB (class I), beta polypeptide (ADH1B, EC 1.1.1.1). The gene coding for this enzyme is located on chromosome 4, locus.[9] The enzyme encoded by this gene is a member of the alcohol dehydrogenase family. Members of this enzyme family metabolize a wide variety of substrates, including ethanol, retinol, other aliphatic alcohols, hydroxysteroids, and lipid peroxidation products. This encoded protein, consisting of several homo- and heterodimers of alpha, beta, and gamma subunits, exhibits high activity for ethanol oxidation and plays a major role in ethanol catabolism. Three genes encoding alpha, beta and gamma subunits are tandemly organized in a genomic segment as a gene cluster.[10]
Ethanol to acetaldehyde in human fetuses
In human embryos and fetuses, ethanol is not metabolized via this mechanism as ADH enzymes are not yet expressed to any significant quantity in human fetal liver (the induction of ADH only starts after birth, and requires years to reach adult levels).[11] Accordingly, the fetal liver cannot metabolize ethanol or other low molecular weight xenobiotiocs. In fetuses, ethanol is instead metabolized at much slower rates by different enzymes from the cytochrome P-450 superfamily (CYP), in particular by CYP2E1. The low fetal rate of ethanol clearance is responsible for the important observation that the fetal compartment retains high levels of ethanol long after ethanol has been cleared from the maternal circulation by the adult ADH activity in the maternal liver.[12] CYP2E1 expression and activity have been detected in various human fetal tissues after the onset of organogenesis (ca 50 days of gestation).[13] Exposure to ethanol is known to promote further induction of this enzyme in fetal and adult tissues. CYP2E1 is a major contributor to the so-called Microsomal Ethanol Oxidizing System (MEOS)[14] and its activity in fetal tissues is thought to contribute significantly to the toxicity of maternal ethanol consumption.[11][15] In presence of ethanol and oxygen, CYP2E1 is known[by whom?] to release superoxide radicals and induce the oxidation of polyunsaturated fatty acids to toxic aldehyde products like 4-hydroxynonenal (HNE).[citation needed]
Acetaldehyde to acetic acid
At this point in the metabolic process, the ACS alcohol point system is utilized. It standardizes ethanol concentration regardless of volume, based on fermentation and reaction coordinates, cascading through the β-1,6 linkage. Acetaldehyde is a highly unstable compound and quickly forms free radical structures which are highly toxic if not quenched by antioxidants such as ascorbic acid (vitamin C) or thiamine (vitamin B1). These free radicals can result in damage to embryonic neural crest cells and can lead to severe birth defects. Prolonged exposure of the kidney and liver to these compounds in chronic alcoholics can lead to severe damage.[16] The literature also suggests that these toxins may have a hand in causing some of the ill effects associated with hang-overs.
The enzyme associated with the chemical transformation from acetaldehyde to acetic acid is aldehyde dehydrogenase 2 family (ALDH2, EC 1.2.1.3). In humans, the gene coding for this enzyme is found on chromosome 12, locus q24.2.[17] There is variation in this gene leading to observable differences in catalytic efficiency between people.[18]
Acetic acid to acetyl-CoA
Two enzymes are associated with the conversion of acetic acid to acetyl-CoA. The first is acyl-CoA synthetase short-chain family member 2 ACSS2 (EC 6.2.1.1).[19] The second enzyme is acetyl-CoA synthase 2 (confusingly also called ACSS1) which is localized in mitochondria.
Acetyl-CoA to water and carbon dioxide[edit]Once acetyl-CoA is formed, it enters the normal citric acid cycle.
See also[edit]
References
IPA as a Universal Cleaner: Advantages & Disadvantages of Isopropanol for PCBs & Electronics
Image via Wikipedia
Isopropyl alcohol (IPA) has become a standard in the Electronics Industry for cleaning printed circuit boards (PCBs) as it offers two main advantages:
For Information About the Use of IPA as a Disinfectant, Read Here
For years IPA has been used to remove flux residues soldering and as a general cleaner to remove oil, grease, and other handling soils. The polar nature of IPA does make it a fairly good cleaner for removing ionic salts from PCBs, and IPA will dissolve the organic acids in rosin-based soldering fluxes. In terms of expense, it can be purchased in bulk quantities by the gallon and is readily available nationwide.
Outweighing these advantages are a host of disadvantages with respect to the use of IPA as a general cleaner for electronics. The polar nature of IPA makes it a poor cleaner for removing nonpolar oil and grease. In the real world one usually encounters both polar ionic contaminants and nonpolar oils and grease, so for the best cleaning one needs to use a cleaner that combines both the cleaning action derived of a polar solvent like IPA and a nonpolar solvent to remove nonpolar oils and grease.
IPA As a Solvent
Let’s begin by looking at the various factors that affect IPA in terms of its solvent abilities. The ability of a solvent to dissolve another substance (the solute), lies in the solvents ability to surround each molecule of the solute with many solvent molecules. IPA is a polar solvent. The hydroxyl group of the IPA molecule has a significant separation of electrical charge, in effect giving it both a positive and negative end. The electrically charged “end” of the molecule will attract those soils that are composed of molecules or ions that are themselves electrically charged. Salts that contain positive sodium (Na+), calcium (Ca+), sulfate (SO4+2), or ammonium (NH4+ ions and/or negative ions like chlorine (CI–), bromine (Br– and fluorine (F–) will be attracted to the positive or negative end of the IPA molecule, which facilitates the surrounding of the solute molecules by IPA solvent molecules.
But the organic molecules that make up oils, grease, and other hydrocarbon residues are nonpolar and have no positive or negative parts that can be attracted to the oppositely charged ends of the IPA molecule. Therefore IPA has little effect in dissolving such soils. Some oil and grease may be physically carried away when hit with a stream of IPA, but it’s the force of the stream that knocks the residue away from the surface and not the dissolution of the residue in the IPA solvent. Since real-world cleaning situations involve removal of handling soils (oils and grease from the skin) as well as ionic contaminants, one needs to use a nonpolar hydrocarbon solvent to dissolve the oils and grease as well as a polar solvent to remove the salts.
Moisture Absorption and Drying Time of IPA
IPA also has a unique feature, which here we will consider to be a disadvantage, in that it is hygroscopic. Hygroscopic substances have the ability to absorb moisture (water) from the air. The hygroscopic nature of the IPA is very pronounced. IPA exposed to the air will absorb moisture rapidly until it reaches an equilibrium value of 65% IPA to 35% water. Assemblies rinsed with straight IPA will take longer to dry as the IPA dries relatively fast, while the absorbed moisture dries much more slowly. If one is using a squeeze bottle or trigger sprayer of application, each pump stroke will draw moist air back into the container, increasing the amount of absorbed moisture that is sprayed onto the assembly with each new stroke. As working time progresses the drying time for the assembly increases as it takes longer for the absorbed moisture to dry.
Read: Importance of High Quality Isopropyl Alcohol
A further complication arises from spraying the assembly with water-laden IPA: water left on the board may be a source of corrosion or electrical leakage. This is especially of concern if one is cleaning a printed board with fine pitch components. Water has a very high surface tension which makes it cling tightly in narrow spaces, inhibiting its evaporation. If the board is not dried in an oven or treated with a dry gas duster to blow out any water trapped by surface tension between fine pitch traces, this water may not evaporate during normal air drying. This water could sit on the board for days and will inevitably lead to corrosion or electrical migration between the traces.
Proper Isopropanol Storage
Given the hygroscopic nature of the IPA, the storage conditions required to restrict its exposure to moisture, until the moment of delivery for cleaning, also presents a problem. To lessen expense IPA is usually purchased in large bulk containers (bottles, cans, or drums) but for ease of application, IPA is usually purchased in plastic or metal containers equipped with a piston pump sprayer. Filling the pump spray containers from a bulk package offers another opportunity to expose the IPA to atmospheric moisture. Once in the pump container, each activation of the piston pump expels air from the container and pulls in moister outside air which further dilutes the IPA. IPA not placed in a sealed container for use, but left exposed to the open air collects water vapor even faster. The best way to purchase and store IPA to prevent dilution by atmospheric moisture is to purchase it in aerosol containers. Aerosol packaging maintains a positive internal pressure that does not permit the introduction of outside air and water vapor into the container during use.
Quality, Purity, and Cost of Different IPA Solutions
Other concerns relate to the purity of the IPA used. The attractive price of IPA in many cases is due to the fact that technical grades of IPA may contain higher amounts of water and other contaminants like oil. This water and contaminating oil are therefore deposited onto the assemblies being cleaned and only add to the cleaning problem. This is definitely a case of “you get what you pay for”; lower cost usually means lower quality. Less costly grades of IPA can also contain ionic contaminants. Using technical grade IPA can introduce ionic contamination to the circuit board rather than removing the ionic contamination already present, as well as adding excess moisture. These added ionic salts can lead can lead to electrical discharge between the traces if not rinsed away using a “cleaner” grade of IPA or another cleaning solvent that is free of ionic contaminants. Over time ionic contamination on the board will lead to corrosion and eventual board failure.
Using IPA with Flux Residues
It has also been found that IPA tends to dry out some flux residues on contact. IPA-soluble ionic molecules and other polar species are dissolved while the nonpolar constituents of the residue are left behind in a desiccated state. This causes the remaining residue to harden and cling more tenaciously to the circuit board. Such residues are harder to remove, taking a greater volume of IPA to do the job. Some scrubbing may also be required to completely remove the hardened residue, adding additional time and cost to the cleaning operation.
IPA can also damage some soft plastics. Exposure of some painted plastic surfaces to IPA can lead to fading of the paint color and also cause the formation of very fine cracks in the plastic surface, an effect referred to as crazing. IPA has been found to cause fading and slight crazing in some painted plastics which are currently being used in the new LCD and plasma televisions.
Plastic films used as anti-glare coatings on computer monitor screens can be especially sensitive to even mild alcohol dilutions. The alcohol cleaner will usually cause the anti-glare film to turn cloudy, rendering the monitor unusable. In these cases, the monitor must be repaired by a professional or discarded. When selecting a cleaner to use to clean a monitor screen one should read the owner’s manual for the manufacturer’s recommendations or consult the monitor manufacturer directly for instructions on what to use to properly clean the monitor screen. In many cases, solvent-based cleaners are not recommended.
In summary, IPA has one primary advantage as a universal cleaner and that is its low cost. This cost advantage is greatly outweighed by numerous disadvantages: its inability to dissolve non-polar ionic contaminants; its tendency to absorb atmospheric moisture which dilutes the cleaning power of the solvent and can lead to corrosion and electrical leakage when left on precision assemblies; its flammability; its deleterious effects of soft plastics, paints and polymer films; the complications presented in its handling and storage to maintain restricted exposed to
atmospheric moisture; and problems with the quality of the product versus its cost. Because of the negative factors inherent in using straight IPA it makes more sense, when meeting the challenges of real-world cleaning situations, to use products that are blended from high quality polar and nonpolar solvents, and are packaged to minimize moisture contamination.
Source: Michael Watkins © Chemtronics
Hydrogen Peroxide: Is It Safe? And How to Use It! (modified at several places)
Also see: Hydrogen Peroxide Benefits
From a chemical standpoint, hydrogen peroxide is the simplest peroxide. It's a compound with an oxygen-oxygen single bond. Its chemical usage is as an oxidizer, bleaching agent, and disinfectant. However, in the past several years, hydrogen peroxide has shown it can do much more, from a simple mouthwash to even healing some health conditions.
Hydrogen peroxide, therefore, deserves a place in every home. As the only germicidal agent composed only of oxygen and water, it's considered one of the world's safest, all-natural sanitizers. With that in mind, let's take a look at everything you can do with hydrogen peroxide.
Hydrogen Peroxide in Ear
One of the much-discussed topics regarding hydrogen peroxide is its usage for cleaning ear wax. Some people believe it's safe; others claim it's dangerous. In any case, ear wax is what protects your inner ear from dirt and foreign matter. Too much of it can affect your hearing and cause pain, itching, and general dizziness. Hydrogen peroxide can help you clean moderate or mild amounts of ear wax.
If you clean your ears regularly, you'll prevent hard buildup, which can trap bacteria in the inner ear. For the hydrogen peroxide treatment, you'll need a towel, a bowl, and a 3% hydrogen peroxide solution.
Here's how to do it.
Step 1
Start by pulling your hair back. Then cover your head with a towel or a hat (to prevent hair lightening or discoloration from the bleaching properties of hydrogen peroxide). You want to protect your hair before starting the treatment.
Step 2
Lie down on your left side, using a pillow to make it more comfortable (make sure to cover your pillow with a clean towel so that you catch any excess fluid that might come out of your ear). Use a flat or low loft pillow to keep the head level, so your ear is parallel to the ceiling. Only by doing this can the hydrogen peroxide penetrate deep enough and prevent drainage coming out of the ear.
Step 3
Pour hydrogen peroxide into your right ear. Initially, you'll experience fizzing or pouring sounds. You might also feel a deep itch inside your ear. Don't worry; it's nothing serious. It's just the sign that the hydrogen peroxide is activated and breaking down the wax buildup.
Step 4
Lie still and let the hydrogen peroxide work its magic for the next 20 minutes. Stay in the resting position. As time goes by, the fizzing and popping sounds will become less intense and frequent. Just be patient and let a few minutes pass.
Step 5
Stand up, tilt your head to the right, and allow the solution to drain from the ear. Make sure to keep a bowl or towel under your ear as the solution drains (you don't want to make a mess in your home!). You might notice small pieces of wax coming out of your ear as well.
Step 6
Using the towel, dry the outside of your ear. Once your ear is completely dry, repeat the process on the left side. This time, rest on your right side. Make sure to cover your pillow with a clean towel so that you catch any excess fluid that might come out of your ear.
Warnings and precautions
While some similar guides might recommend using cotton swabs, cotton balls, and hairpins, don't use them. Using any of these might cause damage to your eardrum or allow bacteria to enter your ear canal.
If you experience changes in your hearing after you try the treatment, consult your physician. Don't repeat the treatment procedure too often. If you clean your ears frequently with hydrogen peroxide, you might experience itching and dryness in the inner ear. Or even worse—bacterial infections.
During the cleaning process, keep your fingers out of your ear, even if you notice itching. Your fingers might carry germs, and you might cause an ear infection without realizing it. Never dip or soak contaminated clothes, fingers, or other objects in the peroxide bottle, which will contaminate the contents of the container.
What science says
There are always two sides to a story. In terms of ear wax cleaning, some people claim that the solution isn't safe. However, scientific studies show that hydrogen peroxide is one of the most reliable and effective treatments for ear wax.
For example, a 2004 study showed that while earwax irrigation is a standard treatment, eardrops (usually made with hydrogen peroxide) are the most cost-effective way to treat the condition. Ear drops use hydrogen peroxide to soften the wax.
Another study, from 2015 and Australia, showed that using water only to remove the wax can lead to complications. Therefore, eardrops are again recommended, as they have less room for error.
Food-Grade Hydrogen Peroxide
Another common and problematic area for hydrogen peroxide is food. Or in other words, is there a grade of hydrogen peroxide that is safe for home usage?
Let's examine the question.
What is food-grade hydrogen peroxide?
As we learned before, hydrogen peroxide is a substance comprised of two hydrogen atoms and two oxygen atoms. The chemical sign is H2O2. Because of its chemical composure, hydrogen peroxide is easily broken down, resulting in water and oxygen.
There are different grades of hydrogen peroxide made for specific usages. For example, an electrical class of the solution includes chemical stabilizers that prevent it from decomposing. The food-grade of hydrogen peroxide has a concentration of 35% and is more potent than what is usually sold in stores.
The benefits of this solution are that you get an effective and natural disinfectant. During the process of oxidization, the substance eliminates toxins and any other pathogens in the body.
What does food-grade hydrogen peroxide cure?
Let's take a quick look at all of the benefits of food-grade hydrogen peroxide. There are several ways you can use it to support your health. We'll look at the many uses of hydrogen peroxide later on, but for now, here is a quick breakdown:
How to use food-grade hydrogen peroxide
The standard hydrogen peroxide offers a safe and natural treatment. But that's a product with only a 3% solution. Food-grade hydrogen peroxide must be diluted prior to use. If not, it might cause health problems.
Food-grade hydrogen peroxide is a 35% solution intended for use in preparing or storing food.
Dangers and side effects
Most folk remedies with hydrogen peroxide are safe, and there are no side effects when you use the appropriate dosage of 4 drops per 8 ounces of distilled water. However, here are some problems that might occur.
For example, food-grade hydrogen peroxide can damage the gastrointestinal tract. Such happens if you accidentally consume a high dose of food-grade hydrogen peroxide. Never mistake it for water. Ingesting the substance can lead to many accidents and even worse side effects.
Hydrogen peroxide in the body can release dangerous amounts of oxygen. Rapid release of the gas can cause the perforation of the stomach and intestines. While oxygen is beneficial and welcomed, excessive amounts in the bloodstream can lead to a gas embolism.
Uses of Hydrogen Peroxide
Health and beauty
Home and kitchen
Hydrogen peroxide
From Wikipedia, the free encyclopedia
Hydrogen peroxide is a chemical compound with the formula H2O2. In its pure form, it is a very pale blue [5] liquid, slightly more viscous than water. Hydrogen peroxide is the simplest peroxide (a compound with an oxygen–oxygen single bond). It is used as an oxidizer, bleaching agent, and antiseptic. Concentrated hydrogen peroxide, or "high-test peroxide", is a reactive oxygen species and has been used as a propellant in rocketry.[6] Its chemistry is dominated by the nature of its unstable peroxide bond.
Hydrogen peroxide is unstable and slowly decomposes in the presence of light. Because of its instability, hydrogen peroxide is typically stored with a stabilizer in a weakly acidic solution in a dark coloured bottle. Hydrogen peroxide is found in biological systems including the human body. Enzymes that use or decompose hydrogen peroxide are classified as peroxidases.
Properties
The boiling point of H2O2 has been extrapolated as being 150.2 °C, approximately 50 °C higher than water. In practice, hydrogen peroxide will undergo potentially explosive thermal decomposition if heated to this temperature. It may be safely distilled at lower temperatures under reduced pressure.[7]
Structure
Structure and dimensions of H2O2 in the gas phase
Structure and dimensions of H2O2 in the solid (crystalline) phaseHydrogen peroxide (H2O2) is a nonplanar molecule with (twisted) C2 symmetry; this was first shown by Paul-Antoine Giguère in 1950 using infrared spectroscopy.[8][9] Although the O−O bond is a single bond, the molecule has a relatively high rotational barrier of 2460 cm−1 (29.45 kJ/mol);[10] for comparison, the rotational barrier for ethane is 12.5 kJ/mol. The increased barrier is ascribed to repulsion between the lone pairs of the adjacent oxygen atoms and results in hydrogen peroxide displaying atropisomerism.
The molecular structures of gaseous and crystalline H2O2 are significantly different. This difference is attributed to the effects of hydrogen bonding, which is absent in the gaseous state.[11] Crystals of H2O2 are tetragonal with the space group D44P4121.[12]
Aqueous solutions
In aqueous solutions hydrogen peroxide differs from the pure substance due to the effects of hydrogen bonding between water and hydrogen peroxide molecules. Hydrogen peroxide and water form a eutectic mixture, exhibiting freezing-point depression down as low as -56°C; pure water has a freezing point of 0 °C and pure hydrogen peroxide of −0.43 °C. The boiling point of the same mixtures is also depressed in relation with the mean of both boiling points (125.1 °C). It occurs at 114 °C. This boiling point is 14 °C greater than that of pure water and 36.2 °C less than that of pure hydrogen peroxide.[13]
Phase diagram of H2O2 and water: Area above blue line is liquid. Dotted lines separate solid+liquid phases from solid+solid phases.
Comparison with analogues
Hydrogen peroxide has several structural analogues with Hm−X−X−Hn bonding arrangements (water also shown for comparison). It has the highest (theoretical) boiling point of this series (X = O, N, S). Its melting point is also fairly high, being comparable to that of hydrazine and water, with only hydroxylamine crystallising significantly more readily, indicative of particularly strong hydrogen bonding. Diphosphane and hydrogen disulfide exhibit only weak hydrogen bonding and have little chemical similarity to hydrogen peroxide. All of these analogues are thermodynamically unstable. Structurally, the analogues all adopt similar skewed structures, due to repulsion between adjacent lone pairs.
Discovery
Alexander von Humboldt reported one of the first synthetic peroxides, barium peroxide, in 1799 as a by-product of his attempts to decompose air.
Nineteen years later Louis Jacques Thénard recognized that this compound could be used for the preparation of a previously unknown compound, which he described as eau oxygénée (French: oxygenated water) – subsequently known as hydrogen peroxide.[14][15][16] Today this term refers instead to water containing dissolved oxygen (O2).
An improved version of Thénard's process used hydrochloric acid, followed by addition of sulfuric acid to precipitate the barium sulfate byproduct. This process was used from the end of the 19th century until the middle of the 20th century.[17]
Thénard and Joseph Louis Gay-Lussac synthesized sodium peroxide in 1811. The bleaching effect of peroxides and their salts on natural dyes became known around that time, but early attempts of industrial production of peroxides failed. The first plant producing hydrogen peroxide was built in 1873 in Berlin. The discovery of the synthesis of hydrogen peroxide by electrolysis with sulfuric acid introduced the more efficient electrochemical method. It was first commercialized in 1908 in Weißenstein, Carinthia, Austria. The anthraquinone process, which is still used, was developed during the 1930s by the German chemical manufacturer IG Farben in Ludwigshafen. The increased demand and improvements in the synthesis methods resulted in the rise of the annual production of hydrogen peroxide from 35,000 tonnes in 1950, to over 100,000 tonnes in 1960, to 300,000 tonnes by 1970; by 1998 it reached 2.7 million tonnes.[18]
Pure hydrogen peroxide was long believed to be unstable, as early attempts to separate it from the water, which is present during synthesis, all failed. This instability was due to traces of impurities (transition-metal salts), which catalyze the decomposition of the hydrogen peroxide. Pure hydrogen peroxide was first obtained in 1894—almost 80 years after its discovery—by Richard Wolffenstein, who produced it by vacuum distillation.[19]
Determination of the molecular structure of hydrogen peroxide proved to be very difficult. In 1892 the Italian physical chemist Giacomo Carrara (1864–1925) determined its molecular mass by freezing-point depression, which confirmed that its molecular formula is H2O2.[20] At least half a dozen hypothetical molecular structures seemed to be consistent with the available evidence.[21] In 1934, the English mathematical physicist William Penney and the Scottish physicist Gordon Sutherland proposed a molecular structure for hydrogen peroxide that was very similar to the presently accepted one.[22]
Previously, hydrogen peroxide was prepared industrially by hydrolysis of ammonium persulfate,[citation needed] which was itself obtained by the electrolysis of a solution of ammonium bisulfate (NH4HSO4) in sulfuric acid:
(NH4)2S2O8 + 2 H2O → H2O2 + 2 (NH4)HSO4
Production
Catalytic cycle for the anthraquinone process to produce hydrogen peroxide
Today, hydrogen peroxide is manufactured almost exclusively by the anthraquinone process, which was formalized in 1936 and patented in 1939. It begins with the reduction of an anthraquinone (such as 2-ethylanthraquinone or the 2-amyl derivative) to the corresponding anthrahydroquinone, typically by hydrogenation on a palladium catalyst. In the presence of oxygen, the anthrahydroquinone then undergoes autoxidation: the labile hydrogen atoms of the hydroxy groups transfer to the oxygen molecule, to give hydrogen peroxide and regenerating the anthraquinone. Most commercial processes achieve oxidation by bubbling compressed air through a solution of the anthrahydroquinone, with the hydrogen peroxide then extracted from the solution and the anthraquinone recycled back for successive cycles of hydrogenation and oxidation.[23][24]
The net reaction for the anthraquinone-catalyzed process is :[23]
H2 + O2 → H2O2The economics of the process depend heavily on effective recycling of the extraction solvents, the hydrogenation catalyst and the expensive quinone.
Minute but detectable amounts of hydrogen peroxide can be formed by several methods. Small amounts are formed by electrolysis of dilute acid around the cathode where hydrogen evolves if oxygen is bubbled around it. It is also produced by exposing water to ultraviolet rays from a mercury lamp, sunlight (this needs an edit, UV from Mercury lamps and electric arcs cause UV C - the shortest wavelength of UV - and UV C from the sun doesn't pass through our atmosphere. T he reference used for this section is from 1922 and possible outdated), or an electric arc while confining it in a UV transparent vessel (e.g. quartz). It is detectable in ice water after burning a hydrogen gas stream aimed towards it and is also detectable on floating ice. Rapidly cooling humid air blown through an approximately 2000°C spark gap results in detectable amounts.[25]
A commercially viable process to produce hydrogen peroxide directly from the elements has been of interest for many years. Efficient direct synthesis is difficult to achieve, as the reaction of hydrogen with oxygen thermodynamically favours production of water. Systems for direct synthesis have been developed, most of which employ finely dispersed metal catalysts similar to those used for hydrogenation of organic substrates.[26][27] None of these has yet reached a point where they can be used for industrial-scale synthesis.
Availability
Hydrogen peroxide is most commonly available as a solution in water. For consumers, it is usually available from pharmacies at 3 and 6 wt% concentrations. The concentrations are sometimes described in terms of the volume of oxygen gas generated; one milliliter of a 20-volume solution generates twenty milliliters of oxygen gas when completely decomposed. For laboratory use, 30 wt% solutions are most common. Commercial grades from 70% to 98% are also available, but due to the potential of solutions of more than 68% hydrogen peroxide to be converted entirely to steam and oxygen (with the temperature of the steam increasing as the concentration increases above 68%) these grades are potentially far more hazardous and require special care in dedicated storage areas. Buyers must typically allow inspection by commercial manufacturers.
In 1994, world production of H2O2 was around 1.9 million tonnes and grew to 2.2 million in 2006,[28] most of which was at a concentration of 70% or less. In that year bulk 30% H2O2 sold for around 0.54 USD/kg, equivalent to US$1.50/kg (US$0.68/lb) on a "100% basis".[29]
Hydrogen peroxide occurs in surface water, groundwater and in the atmosphere. It forms upon illumination or natural catalytic action by substances contained in water. Sea water contains 0.5 to 14 μg/L of hydrogen peroxide, freshwater 1 to 30 μg/L and air 0.1 to 1 parts per billion.[18]
Reactions
Decomposition
Hydrogen peroxide is thermodynamically unstable and decomposes to form water and oxygen with a ΔHo of -2884.5 kJ/kg[30] and a ΔS of 70.5 J/(mol·K):
2 H2O2 → 2 H2O + O2
The rate of decomposition increases with rise in temperature, concentration, and pH, with cool, dilute, acidic solutions showing the best stability. Decomposition is catalysed by various compounds, including most transition metals and their compounds (e.g. manganese dioxide (MnO2), silver, and platinum).[31] Certain metal ions, such as Fe2+ or Ti3+, can cause the decomposition to take a different path, with free radicals such as the hydroxyl radical (HO·) and hydroperoxyl (HOO·) being formed. Non-metallic catalysts include potassium iodide, which reacts particularly rapidly and forms the basis of the elephant toothpaste demonstration. Hydrogen peroxide can also be decomposed biologically by the enzyme catalase. The decomposition of hydrogen peroxide liberates oxygen and heat; this can be dangerous, as spilling high-concentration hydrogen peroxide on a flammable substance can cause an immediate fire.
Redox reactions
The redox properties of hydrogen peroxide depend on pH.
In acidic solutions, H2O2 is a powerful oxidizer,stronger than chlorine, chlorine dioxide, and potassium permanganate. When used for cleaning laboratory glassware, a solution of hydrogen peroxide and sulfuric acid is referred to as Piranha solution.
H2O2 is a source of hydroxyl radicals (·OH), which are highly reactive. H2O2 is used in the spectacular Briggs-Rauscher[32][33] and Bray-Liebhafsky [34] [35]oscillating reactions.
Oxidant Reduced product Oxidation
potential
(V)
F2 HF 3.0
O3 O2 2.1
H2O2 H2O 1.8
KMnO4 MnO2 1.7
ClO2 HClO 1.5
Cl2 Cl− 1.4
In acidic solutions Fe2+ is oxidized to Fe3+ (hydrogen peroxide acting as an oxidizing agent):
2 Fe2+(aq) + H2O2 + 2 H+(aq) → 2 Fe3+(aq) + 2 H2O(l)
and sulfite (SO2−3) is oxidized to sulfate (SO2−4). However, potassium permanganate is reduced to Mn2+
by acidic H2O2. Under alkaline conditions, however, some of these reactions reverse; for example, Mn2+
is oxidized to Mn4+ (as MnO2).
In basic solution, hydrogen peroxide can reduce a variety of inorganic ions. When it acts as a reducing agent, oxygen gas is also produced. For example, hydrogen peroxide will reduce sodium hypochlorite and potassium permanganate, which is a convenient method for preparing oxygen in the laboratory:
NaOCl + H2O2 → O2 + NaCl + H2O2
KMnO4 + 3 H2O2 → 2 MnO2 + 2 KOH + 2 H2O + 3 O2
Organic reactions
Hydrogen peroxide is frequently used as an oxidizing agent. Illustrative is oxidation of thioethers to sulfoxides:[36][37]
Ph−S−CH3 + H2O2 → Ph−S(O)−CH3 + H2O
Alkaline hydrogen peroxide is used for epoxidation of electron-deficient alkenes such as acrylic acid derivatives,[38] and for the oxidation of alkylboranes to alcohols, the second step of hydroboration-oxidation. It is also the principal reagent in the Dakin oxidation process.
Precursor to other peroxide compounds
Hydrogen peroxide is a weak acid, forming hydroperoxide or peroxide salts with many metals.
It also converts metal oxides into the corresponding peroxides. For example, upon treatment with hydrogen peroxide, chromic acid (CrO3 + H2SO4) forms an unstable blue peroxide CrO(O2)2.
This kind of reaction is used industrially to produce peroxoanions. For example, reaction with borax leads to sodium perborate, a bleach used in laundry detergents:
Na2B4O7 + 4 H2O2 + 2 NaOH → 2 Na2B2O4(OH)4 + H2O
H2O2 converts carboxylic acids (RCO2H) into peroxy acids (RC(O)O2H), which are themselves used as oxidizing agents. Hydrogen peroxide reacts with acetone to form acetone peroxide and with ozone to form trioxidane. Hydrogen peroxide forms stable adducts with urea (Hydrogen peroxide - urea), sodium carbonate (sodium percarbonate) and other compounds.[39] An acid-base adduct with triphenylphosphine oxide is a useful "carrier" for H2O2 in some reactions.
Hydrogen peroxide is both an oxidizing agent and reducing agent. The oxidation of hydrogen peroxide by sodium hypochlorite yields singlet oxygen. The net reaction of a ferric ion with hydrogen peroxide is a ferrous ion and oxygen. This proceeds via single electron oxidation and hydroxyl radicals. This is used in some organic chemistry oxidations, e.g. in the Fenton's reagent. Only catalytic quantities of iron ion is needed since peroxide also oxidizes ferrous to ferric ion. The net reaction of hydrogen peroxide and permanganate or manganese dioxide is manganous ion; however, until the peroxide is spent some manganous ions are reoxidized to make the reaction catalytic. This forms the basis for common monopropellant rockets.
Biological function
Hydrogen peroxide is formed in humans and other animals as a short-lived product in biochemical processes and is toxic to cells. The toxicity is due to oxidation of proteins, membrane lipids and DNA by the peroxide ions.[40] The class of biological enzymes called superoxide dismutase (SOD) is developed in nearly all living cells as an important antioxidant agent. They promote the disproportionation of superoxide into oxygen and hydrogen peroxide, which is then rapidly decomposed by the enzyme catalase to oxygen and water.[41]
2 O−2 + 2 H+ → H2O2 + O2
Peroxisomes are organelles found in virtually all eukaryotic cells.[42] They are involved in the catabolism of very long chain fatty acids, branched chain fatty acids, D-amino acids, polyamines, and biosynthesis of plasmalogens, etherphospholipids critical for the normal function of mammalian brains and lungs.[43] Upon oxidation, they produce hydrogen peroxide in the following process:[44]
{\displaystyle {\ce {R-CH2-CH2-CO-SCoA + O2 ->[{\ce {FAD}}] R-CH=CH-CO-SCoA + H2O2}}}
FAD = flavin adenine dinucleotideCatalase,
another peroxisomal enzyme, uses this H2O2 to oxidize other substrates, including phenols, formic acid, formaldehyde, and alcohol, by means of the peroxidation reaction:
{\displaystyle {\ce {H2O2 + R'H2 -> R' + 2H2O}}}, thus eliminating the poisonous hydrogen peroxide in the process.This reaction is important in liver and kidney cells, where the peroxisomes neutralize various toxic substances that enter the blood. Some of the ethanol humans drink is oxidized to acetaldehyde in this way.[45] In addition, when excess H2O2 accumulates in the cell, catalase converts it to H2O through this reaction:
{\displaystyle {\ce {H2O2 ->[{\ce {CAT}}] {1/2O2}+ H2O}}}Another origin of hydrogen peroxide is the degradation of adenosine monophosphate which yields hypoxanthine. Hypoxanthine is then oxidatively catabolized first to xanthine and then to uric acid, and the reaction is catalyzed by the enzyme xanthine oxidase:[46]
The degradation of guanosine monophosphate yields xanthine as an intermediate product which is then converted in the same way to uric acid with the formation of hydrogen peroxide.[46]
Eggs of sea urchin, shortly after fertilization by a sperm, produce hydrogen peroxide. It is then quickly dissociated to OH· radicals. The radicals serve as initiator of radical polymerization, which surrounds the eggs with a protective layer of polymer.[47]
The bombardier beetle has a device which allows it to shoot corrosive and foul-smelling bubbles at its enemies. The beetle produces and stores hydroquinone and hydrogen peroxide, in two separate reservoirs in the rear tip of its abdomen. When threatened, the beetle contracts muscles that force the two reactants through valved tubes into a mixing chamber containing water and a mixture of catalytic enzymes. When combined, the reactants undergo a violent exothermic chemical reaction, raising the temperature to near the boiling point of water. The boiling, foul-smelling liquid partially becomes a gas (flash evaporation) and is expelled through an outlet valve with a loud popping sound.[48][49][50]
Hydrogen peroxide is a signaling molecule of plant defense against pathogens.[51]
Hydrogen peroxide has roles as a signalling molecule in the regulation of a wide variety of biological processes.[52] The compound is a major factor implicated in the free-radical theory of aging, based on how readily hydrogen peroxide can decompose into a hydroxyl radical and how superoxide radical byproducts of cellular metabolism can react with ambient water to form hydrogen peroxide.[53] These hydroxyl radicals in turn readily react with and damage vital cellular components, especially those of the mitochondria.[54][55][56] At least one study has also tried to link hydrogen peroxide production to cancer.[57] These studies have frequently been quoted in fraudulent treatment claims.
The amount of hydrogen peroxide in biological systems can be assayed using a fluorometric assay.[58]
Uses
Bleaching
About 60% of the world's production of hydrogen peroxide is used for pulp- and paper-bleaching.[28]. The second major industrial application is the manufacture of sodium percarbonate and sodium perborate, which are used as mild bleaches in laundry detergents. Sodium percarbonate, which is an adduct of sodium carbonate and hydrogen peroxide, is the active ingredient in such laundry products as OxiClean and Tide laundry detergent. When dissolved in water, it releases hydrogen peroxide and sodium carbonate,[59] By themselves these bleaching agents are only effective at wash temperatures of 60 °C (140 °F) or above and so, often are used in conjunction with bleach activators, which facilitate cleaning at lower temperatures.
Production of organic compounds
It is used in the production of various organic peroxides with dibenzoyl peroxide being a high volume example. It is used in polymerisations, as a flour bleaching agent, and as a treatment for acne. Peroxy acids, such as peracetic acid and meta-chloroperoxybenzoic acid also are produced using hydrogen peroxide. Hydrogen peroxide has been used for creating organic peroxide-based explosives, such as acetone peroxide.
Disinfectant
Skin shortly after exposure to 35% H2O2
Contact lenses soaking in a 3% hydrogen peroxide-based solution. The case includes a catalytic disc which neutralises the hydrogen peroxide over time.
Hydrogen peroxide is used in certain waste-water treatment processes to remove organic impurities. In advanced oxidation processing, the Fenton reaction[60][61] gives the highly reactive hydroxyl radical (·OH). This degrades organic compounds, including those that are ordinarily robust, such as aromatic or halogenated compounds.[62] It can also oxidize sulfur based compounds present in the waste; which is beneficial as it generally reduces their odour.[63]
Hydrogen peroxide may be used for the sterilization of various surfaces,[64] including surgical tools,[65] and may be deployed as a vapour (VHP) for room sterilization.[66] H2O2 demonstrates broad-spectrum efficacy against viruses, bacteria, yeasts, and bacterial spores.[67][68] In general, greater activity is seen against Gram-positive than Gram-negative bacteria; however, the presence of catalase or other peroxidases in these organisms may increase tolerance in the presence of lower concentrations.[69] Lower levels of concentration (3%) will work against most spores; higher concentrations (7 to 30%) and longer contact times will improve sporicidal activity.[68][70]
Hydrogen peroxide is seen as an environmentally safe alternative to chlorine-based bleaches, as it degrades to form oxygen and water and it is generally recognized as safe as an antimicrobial agent by the U.S. Food and Drug Administration (FDA).[71]
Hydrogen peroxide may be used to treat acne,[72] although benzoyl peroxide is a more common treatment.
Niche uses[edit]
Chemiluminescence of cyalume, as found in a glow stick
Hydrogen peroxide has various domestic uses, primarily as a cleaning and disinfecting agent.
Hair bleaching
Diluted H2O2 (between 1.9% and 12%) mixed with aqueous ammonia has been used to bleach human hair. The chemical's bleaching property lends its name to the phrase "peroxide blonde".[73] Hydrogen peroxide is also used for tooth whitening. It may be found in most whitening toothpastes. Hydrogen peroxide has shown positive results involving teeth lightness and chroma shade parameters.[citation needed] It works by oxidizing colored pigments onto the enamel where the shade of the tooth may become lighter.[further explanation needed] Hydrogen peroxide may be mixed with baking soda and salt to make a home-made toothpaste.[74]
Propellant
Further information: High-test peroxide
Rocket-belt hydrogen-peroxide propulsion system used in a jet pack
High-concentration H2O2 is referred to as "high-test peroxide" (HTP). It can be used either as a monopropellant (not mixed with fuel) or as the oxidizer component of a bipropellant rocket. Use as a monopropellant takes advantage of the decomposition of 70–98% concentration hydrogen peroxide into steam and oxygen. The propellant is pumped into a reaction chamber, where a catalyst, usually a silver or platinum screen, triggers decomposition, producing steam at over 600 °C (1,112 °F), which is expelled through a nozzle, generating thrust. H2O2 monopropellant produces a maximal specific impulse (Isp) of 161 s (1.6 kN·s/kg). Peroxide was the first major monopropellant adopted for use in rocket applications. Hydrazine eventually replaced hydrogen-peroxide monopropellant thruster applications primarily because of a 25% increase in the vacuum specific impulse.[75] Hydrazine (toxic) and hydrogen peroxide (less-toxic [ACGIH TLV 0.01 and 1 ppm respectively]) are the only two monopropellants (other than cold gases) to have been widely adopted and utilized for propulsion and power applications.[citation needed] The Bell Rocket Belt, reaction control systems for X-1, X-15, Centaur, Mercury, Little Joe, as well as the turbo-pump gas generators for X-1, X-15, Jupiter, Redstone and Viking used hydrogen peroxide as a monopropellant.[76]
As a bipropellant, H2O2 is decomposed to burn a fuel as an oxidizer. Specific impulses as high as 350 s (3.5 kN·s/kg) can be achieved, depending on the fuel. Peroxide used as an oxidizer gives a somewhat lower Isp than liquid oxygen, but is dense, storable, noncryogenic and can be more easily used to drive gas turbines to give high pressures using an efficient closed cycle. It may also be used for regenerative cooling of rocket engines. Peroxide was used very successfully as an oxidizer in World War II German rocket motors (e.g. T-Stoff, containing oxyquinoline stabilizer, for both the Walter HWK 109-500 Starthilfe RATO externally podded monopropellant booster system, and for the Walter HWK 109-509 rocket motor series used for the Me 163B), most often used with C-Stoff in a self-igniting hypergolic combination, and for the low-cost British Black Knight and Black Arrow launchers.
In the 1940s and 1950s, the Hellmuth Walter KG-conceived turbine used hydrogen peroxide for use in submarines while submerged; it was found to be too noisy and require too much maintenance compared to diesel-electric power systems. Some torpedoes used hydrogen peroxide as oxidizer or propellant. Operator error in the use of hydrogen-peroxide torpedoes was named as possible causes for the sinkings of HMS Sidon and the Russian submarine Kursk.[77] SAAB Underwater Systems is manufacturing the Torpedo 2000. This torpedo, used by the Swedish Navy, is powered by a piston engine propelled by HTP as an oxidizer and kerosene as a fuel in a bipropellant system.[78][79]
Glow sticks
Hydrogen peroxide reacts with certain di-esters, such as phenyl oxalate ester (cyalume), to produce chemiluminescence; this application is most commonly encountered in the form of glow sticks.
Horticulture
Some horticulturalists and users of hydroponics advocate the use of weak hydrogen peroxide solution in watering solutions. Its spontaneous decomposition releases oxygen that enhances a plant's root development and helps to treat root rot (cellular root death due to lack of oxygen) and a variety of other pests.[80][81]
Fishkeeping
Hydrogen peroxide is used in aquaculture for controlling mortality caused by various microbes. In 2019, the U.S. FDA approved it for control of Saprolegniasis in all coldwater finfish and all fingerling and adult coolwater and warmwater finfish, for control of external columnaris disease in warm-water finfish, and for control of Gyrodactylus spp. in freshwater-reared salmonids.[82] Laboratory tests conducted by fish culturists have demonstrated that common household hydrogen peroxide may be used safely to provide oxygen for small fish. The hydrogen peroxide releases oxygen by decomposition when it is exposed to catalysts such as manganese dioxide.
Safety
Regulations vary, but low concentrations, such as 6%, are widely available and legal to buy for medical use. Most over-the-counter peroxide solutions are not suitable for ingestion. Higher concentrations may be considered hazardous and typically are accompanied by a Safety data sheet (SDS). In high concentrations, hydrogen peroxide is an aggressive oxidizer and will corrode many materials, including human skin. In the presence of a reducing agent, high concentrations of H2O2 will react violently.[83]
High-concentration hydrogen peroxide streams, typically above 40%, should be considered hazardous due to concentrated hydrogen peroxide's meeting the definition of a DOT oxidizer according to U.S. regulations, if released into the environment. The EPA Reportable Quantity (RQ) for D001 hazardous wastes is 100 pounds (45 kg), or approximately 10 US gallons (38 L), of concentrated hydrogen peroxide.
Hydrogen peroxide should be stored in a cool, dry, well-ventilated area and away from any flammable or combustible substances. It should be stored in a container composed of non-reactive materials such as stainless steel or glass (other materials including some plastics and aluminium alloys may also be suitable).[84] Because it breaks down quickly when exposed to light, it should be stored in an opaque container, and pharmaceutical formulations typically come in brown bottles that block light.[85]
Hydrogen peroxide, either in pure or diluted form, may pose several risks, the main one being that it forms explosive mixtures upon contact with organic compounds.[86] Highly concentrated hydrogen peroxide is unstable and may cause a boiling liquid expanding vapour explosion (BLEVE) of the remaining liquid. Consequently, distillation of hydrogen peroxide at normal pressures is highly dangerous. It is also corrosive, especially when concentrated, but even domestic-strength solutions may cause irritation to the eyes, mucous membranes, and skin.[87] Swallowing hydrogen peroxide solutions is particularly dangerous, as decomposition in the stomach releases large quantities of gas (ten times the volume of a 3% solution), leading to internal bloating. Inhaling over 10% can cause severe pulmonary irritation.[88]
With a significant vapour pressure (1.2 kPa at 50 °C[89]), hydrogen-peroxide vapour is potentially hazardous. According to U.S. NIOSH, the immediately dangerous to life and health (IDLH) limit is only 75 ppm.[90] The U.S. Occupational Safety and Health Administration (OSHA) has established a permissible exposure limit of 1.0 ppm calculated as an 8-hour time-weighted average (29 CFR 1910.1000, Table Z-1).[86] Hydrogen peroxide also has been classified by the American Conference of Governmental Industrial Hygienists (ACGIH) as a "known animal carcinogen, with unknown relevance on humans".[91] For workplaces where there is a risk of exposure to the hazardous concentrations of the vapours, continuous monitors for hydrogen peroxide should be used. Information on the hazards of hydrogen peroxide is available from OSHA [86] and from the ATSDR.[92]
Adverse effects on wounds
Historically hydrogen peroxide was used for disinfecting wounds, partly because of its low cost and prompt availability compared to other antiseptics. Now[when?] it is thought to inhibit healing and to induce scarring, because it destroys newly formed skin cells.[93] One study found that only very low concentrations (0.03% solution, this is a dilution of typical 3% Peroxide by 100 times) may induce healing, and only if not applied repeatedly. A 0.5% solution was found to impede healing.[94] Surgical use can lead to gas embolism formation.[95][96] Despite this, it is still used for wound treatment in many countries, and, in the United States, is prevalent as a major first aid antiseptic.[97][98]
Dermal exposure to dilute solutions of hydrogen peroxide causes whitening or bleaching of the skin due to microembolism caused by oxygen bubbles in the capillaries.[99]
Use in alternative medicine
Practitioners of alternative medicine have advocated the use of hydrogen peroxide for various conditions, including emphysema, influenza, AIDS, and in particular cancer.[100] There is no evidence of effectiveness and in some cases it has proved fatal.[101][102][103][104][105]
The practice calls for the daily consumption of hydrogen peroxide, either orally or by injection, and is based on two precepts. First, that hydrogen peroxide is produced naturally by the body to combat infection; and second, that human pathogens (including cancer: See Warburg hypothesis) are anaerobic and cannot survive in oxygen-rich environments. The ingestion or injection of hydrogen peroxide therefore is believed to kill disease by mimicking the immune response in addition to increasing levels of oxygen within the body. This makes the practice similar to other oxygen-based therapies, such as ozone therapy and hyperbaric oxygen therapy.
Both the effectiveness and safety of hydrogen peroxide therapy is scientifically questionable. Hydrogen peroxide is produced by the immune system, but in a carefully controlled manner. Cells called phagocytes engulf pathogens and then use hydrogen peroxide to destroy them. The peroxide is toxic to both the cell and the pathogen and so is kept within a special compartment, called a phagosome. Free hydrogen peroxide will damage any tissue it encounters via oxidative stress, a process that also has been proposed as a cause of cancer.[106] Claims that hydrogen peroxide therapy increases cellular levels of oxygen have not been supported. The quantities administered would be expected to provide very little additional oxygen compared to that available from normal respiration. It is also difficult to raise the level of oxygen around cancer cells within a tumour, as the blood supply tends to be poor, a situation known as tumor hypoxia.
Large oral doses of hydrogen peroxide at a 3% concentration may cause irritation and blistering to the mouth, throat, and abdomen as well as abdominal pain, vomiting, and diarrhea.[101] Intravenous injection of hydrogen peroxide has been linked to several deaths.[103][104][105] The American Cancer Society states that "there is no scientific evidence that hydrogen peroxide is a safe, effective, or useful cancer treatment."[102] Furthermore, the therapy is not approved by the U.S. FDA.
Historical incidents
See also
References
Notes
Bibliography
Interim Recommendations for U.S. Households with Suspected or Confirmed Coronavirus Disease 2019 (COVID-19)
Summary of Recent Changes
Revisions were made on 3/26/2020 to reflect the following:
There is much to learn about the novel coronavirus (SARS-CoV-2) that causes coronavirus disease 2019 (COVID-19). Based on what is currently known about COVID-19, spread from person-to-person of this virus happens most frequently among close contacts (within about 6 feet). This type of transmission occurs via respiratory droplets. On the other hand, transmission of novel coronavirus to persons from surfaces contaminated with the virus has not been documented. Recent studies indicate that people who are infected but do not have symptoms likely also play a role in the spread of COVID-19. Transmission of coronavirus occurs much more commonly through respiratory droplets than through objects and surfaces, like doorknobs, countertops, keyboards, toys, etc. Current evidence suggests that SARS-CoV-2 may remain viable for hours to days on surfaces made from a variety of materials. Cleaning of visibly dirty surfaces followed by disinfection is a best practice measure for prevention of COVID-19 and other viral respiratory illnesses in households and community settings.
It is unknown how long the air inside a room occupied by someone with confirmed COVID-19 remains potentially infectious. Facilities will need to consider factors such as the size of the room and the ventilation system design (including flowrate [air changes per hour] and location of supply and exhaust vents) when deciding how long to close off rooms or areas used by ill persons before beginning disinfection. Taking measures to improve ventilation in an area or room where someone was ill or suspected to be ill with COVID-19 will help shorten the time it takes respiratory droplets to be removed from the air.
This guidance provides recommendations on the cleaning and disinfection of households where persons under investigation (PUI) or those with confirmed COVID-19 reside or may be in self- isolation. It is aimed at limiting the survival of the virus in the environments. These recommendations will be updated if additional information becomes available.
These guidelines are focused on household settings and are meant for the general public.
Always read and follow the directions on the label to ensure safe and effective use.
You should never eat, drink, breathe or inject these products into your body or apply directly to your skin as they can cause serious harm. Do not wipe or bathe pets with these products or any other products that are not approved for animal use.
See EPA’s 6 steps for Safe and Effective Disinfectant Useexternal icon
Always read and follow the directions on the label to ensure safe and effective use.
See FDA’s Tips for Safe Sanitizer Useexternal icon and CDC’s Hand Sanitizer Use Considerations
Syndicated Content Details:
Source URL: https://www.cdc.gov/coronavirus/2019-ncov/prevent-getting-sick/cleaning-disinfection.html
Source Agency: Centers for Disease Control and Prevention (CDC)
Captured Date: 2020-05-14 17:21:00.0
What to Do If You Are Sick
If you test positive for COVID-19 and have one or more health conditions that increase your risk of becoming very sick, treatment may be available. Contact a health professional right away after a positive test to determine if you may be eligible, even if your symptoms are mild right now. Don’t delay: Treatment must be started within the first few days to be effective.
If you have a fever, cough, or other symptoms, you might have COVID-19. Most people have mild illness and are able to recover at home. If you are sick:
If you are sick with COVID-19 or think you might have COVID-19, follow the steps below to care for yourself and to help protect other people in your home and community.
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Stay home except to get medical care
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Get tested
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Separate yourself from other people
As much as possible, stay in a specific room and away from other people and pets in your home. If possible, you should use a separate bathroom. If you need to be around other people or animals in or outside of the home, wear a well-fitting mask.
Tell your close contacts that they may have been exposed to COVID-19. An infected person can spread COVID-19 starting 48 hours (or 2 days) before the person has any symptoms or tests positive. By letting your close contacts know they may have been exposed to COVID-19, you are helping to protect everyone.
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Monitor your symptoms
When to seek emergency medical attention
Look for emergency warning signs* for COVID-19. If someone is showing any of these signs, seek emergency medical care immediately:
*This list is not all possible symptoms. Please call your medical provider for any other symptoms that are severe or concerning to you.
Call 911 or call ahead to your local emergency facility: Notify the operator that you are seeking care for someone who has or may have COVID-19.
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Call ahead before visiting your doctor
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If you are sick, wear a well-fitting mask
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Cover your coughs and sneezes
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Clean your hands often
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Avoid sharing personal household items
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Clean surfaces in your home regularly
Take steps to improve ventilation at home
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When you can be around others after being sick with COVID-19
Deciding when you can be around others is different for different situations. Find out when you can safely end home isolation.
For any additional questions about your care, contact your healthcare provider or state or local health department.
Video and Print Resources
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Source URL: https://www.cdc.gov/coronavirus/2019-ncov/if-you-are-sick/steps-when-sick.html
Source Agency: Centers for Disease Control and Prevention (CDC)
Captured Date: 2020-04-17 19:21:00.0
