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The simplest example is tert-butanol (2-methylpropan-2-ol), for which each of R, R', and R" is CH.
In these shorthands, R, R', and R" represent substituents, alkyl or other attached, generally organic groups.
========,4,Alkyl chain variations in alcohols.
Short-chain alcohols have alkyl chains of 1–3 carbons.
Medium-chain alcohols have alkyl chains of 4–7 carbons.
Long-chain alcohols (also known as fatty alcohols) have alkyl chains of 8–21 carbons, and very long-chain alcohols have alkyl chains of 22 carbons or longer.
========,4,Simple alcohols.
"Simple alcohols" appears to be a completely undefined term.
However, simple alcohols are often referred to by common names derived by adding the word "alcohol" to the name of the appropriate alkyl group.
For instance, a chain consisting of one carbon (a methyl group, CH) with an OH group attached to the carbon is called "methyl alcohol" while a chain of two carbons (an ethyl group, CHCH) with an OH group connected to the CH is called "ethyl alcohol."
For more complex alcohols, the IUPAC nomenclature must be used.
Simple alcohols, in particular ethanol and methanol, possess denaturing and inert rendering properties, leading to their use as anti-microbial agents in medicine, pharmacy, and industry.
========,4,Higher alcohols.
Encyclopædia Britannica states, "The higher alcohols—those containing 4 to 10 carbon atoms—are somewhat viscous, or oily, and they have heavier fruity odours.
Some of the highly branched alcohols and many alcohols containing more than 12 carbon atoms are solids at room temperature."
Like ethanol, butanol can be produced by fermentation processes.
Saccharomyces yeast are known to produce these higher alcohols at temperatures above .
The bacterium "Clostridium acetobutylicum" can feed on cellulose to produce butanol on an industrial scale.
========,2,Applications.
Alcohol has a long history of several uses worldwide.
It is found in alcoholic beverages sold to adults, as fuel, and also has many scientific, medical, and industrial uses.
The term alcohol-free is often used to describe a product that does not contain alcohol.
========,3,Alcoholic beverages.
Alcoholic beverages, typically containing 3–40% ethanol by volume, have been produced and consumed by humans since pre-historic times.
Other alcohols such as 2-methyl-2-butanol (found in beer) and γ-hydroxybutyric acid (GHB) are also consumed by humans for their psychoactive effects.
========,3,Antiseptics.
Ethanol can be used as an antiseptic to disinfect the skin before injections are given, often along with iodine.
Ethanol-based soaps are becoming common in restaurants and are convenient because they do not require drying due to the volatility of the compound.
Alcohol based gels have become common as hand sanitizers.
========,3,Fuels.
Some alcohols, mainly ethanol and methanol, can be used as an alcohol fuel.
Fuel performance can be increased in forced induction internal combustion engines by injecting alcohol into the air intake after the turbocharger or supercharger has pressurized the air.
This cools the pressurized air, providing a denser air charge, which allows for more fuel, and therefore more power.
========,3,Solvents.
Hydroxyl groups (-OH), found in alcohols, are polar and therefore hydrophilic (water loving) but their carbon chain portion is non-polar which make them hydrophobic.
The molecule increasingly becomes overall more nonpolar and therefore less soluble in the polar water as the carbon chain becomes longer.
Methanol has the shortest carbon chain of all alcohols (one carbon atom) followed by ethanol (two carbon atoms.)
Alcohols have applications in industry and science as reagents or solvents.
Because of its relatively low toxicity compared with other alcohols and ability to dissolve non-polar substances, ethanol can be used as a solvent in medical drugs, perfumes, and vegetable essences such as vanilla.
In organic synthesis, alcohols serve as versatile intermediates.
========,2,Toxicity.
Ethanol is thought to cause harm partly as a result of direct damage to DNA caused by its metabolites.
Ethanol's toxicity is largely caused by its primary metabolite, acetaldehyde (systematically ethanal) and secondary metabolite, acetic acid.
Many primary alcohols are metabolized into aldehydes then to carboxylic acids whose toxicities are similar to acetaldehyde and acetic acid.
Metabolite toxicity is reduced in rats fed "N"-acetylcysteine and thiamine.
Although the mechanism is unclear, a meta-analysis of 572 studies have shown increased cancer risk from consumption of ethanol.
Tertiary alcohols cannot be metabolized into aldehydes and as a result they cause no hangover or toxicity through this mechanism.
Some secondary and tertiary alcohols are less poisonous than ethanol, because the liver is unable to metabolize them into toxic by-products.
This makes them more suitable for pharmaceutical use as the chronic harms are lower.
Ethchlorvynol and "tert"-amyl alcohol are tertiary alcohols which have seen both medicinal and recreational use.
Other alcohols are substantially more poisonous than ethanol, partly because they take much longer to be metabolized and partly because their metabolism produces substances that are even more toxic.
Methanol (wood alcohol), for instance, is oxidized to formaldehyde and then to the poisonous formic acid in the liver by alcohol dehydrogenase and formaldehyde dehydrogenase enzymes, respectively; accumulation of formic acid can lead to blindness or death.
Likewise, poisoning due to other alcohols such as ethylene glycol or diethylene glycol are due to their metabolites, which are also produced by alcohol dehydrogenase.
Methanol itself, while poisonous (LD 5628 mg/kg, oral, rat), has a much weaker sedative effect than ethanol.
Isopropyl alcohol is oxidized to form acetone by alcohol dehydrogenase in the liver, but has occasionally been abused by alcoholics, leading to a range of adverse health effects.
========,3,Treatment.
An effective treatment to prevent toxicity after methanol or ethylene glycol ingestion is to administer ethanol.
Alcohol dehydrogenase has a higher affinity for ethanol, thus preventing methanol from binding and acting as a substrate.
Any remaining methanol will then have time to be excreted through the kidneys.
========,2,Physical and chemical properties.
Alcohols have an odor that is often described as "biting" and as "hanging" in the nasal passages.
Ethanol has a slightly sweeter (or more fruit-like) odor than the other alcohols.
In general, the hydroxyl group makes the alcohol molecule polar.
Those groups can form hydrogen bonds to one another and to other compounds (except in certain large molecules where the hydroxyl is protected by steric hindrance of adjacent groups).
This hydrogen bonding means that alcohols can be used as protic solvents.
Two opposing solubility trends in alcohols are: the tendency of the polar OH to promote solubility in water, and the tendency of the carbon chain to resist it.
Thus, methanol, ethanol, and propanol are miscible in water because the hydroxyl group wins out over the short carbon chain.
Butanol, with a four-carbon chain, is moderately soluble because of a balance between the two trends.
Alcohols of five or more carbons such as pentanol and higher are effectively insoluble in water because of the hydrocarbon chain's dominance.
All simple alcohols are miscible in organic solvents.
Because of hydrogen bonding, alcohols tend to have higher boiling points than comparable hydrocarbons and ethers.
The boiling point of the alcohol ethanol is 78.29 °C, compared to 69 °C for the hydrocarbon hexane (a common constituent of gasoline), and 34.6 °C for diethyl ether.
Alcohols, like water, can show either acidic or basic properties at the -OH group.
With a pK of around 16-19, they are, in general, slightly weaker acids than water, but they are still able to react with strong bases such as sodium hydride or reactive metals such as sodium.
The salts that result are called alkoxides, with the general formula RO M. Meanwhile, the oxygen atom has lone pairs of nonbonded electrons that render it weakly basic in the presence of strong acids such as sulfuric acid.
For example, with methanol:
Alcohols can be oxidised to give aldehydes, ketones or carboxylic acids, or they can be dehydrated to alkenes.
They can react with carboxylic acids to form ester compounds, and they can (if activated first) undergo nucleophilic substitution reactions.
The lone pairs of electrons on the oxygen of the hydroxyl group also makes alcohols nucleophiles.
For more details, see the reactions of alcohols section below.
As one moves from primary to secondary to tertiary alcohols with the same backbone, the hydrogen bond strength, the boiling point, and the acidity typically decrease.
========,2,Occurrence in nature.
Ethanol occurs naturally as a byproduct of the metabolic process of yeast.
As such, ethanol will be present in any yeast habitat.
Ethanol can commonly be found in overripe fruit.
Methanol is produced naturally in the anaerobic metabolism of many varieties of bacteria, and is commonly present in small amounts in the environment.
Alcohols have been found outside the Solar System at low densities in star-forming regions of interstellar space.
========,2,Production.
========,3,Ziegler and oxo processes.
In the Ziegler process, linear alcohols are produced from ethylene and triethylaluminium followed by oxidation and hydrolysis.
An idealized synthesis of 1-octanol is shown:
The process generates a range of alcohols that are separated by distillation.
Many higher alcohols are produced by hydroformylation of alkenes followed by hydrogenation.
When applied to a terminal alkene, as is common, one typically obtains a linear alcohol:
Such processes give fatty alcohols, which are useful for detergents.
========,3,Hydration reactions.
Low molecular weight alcohols of industrial importance are produced by the addition of water to alkenes.
Ethanol, isopropanol, 2-butanol, and tert-butanol are produced by this general method.
Two implementations are employed, the direct and indirect methods.
The direct method avoids the formation of stable intermediates, typically using acid catalysts.

The simplest example is tert-butanol (2-methylpropan-2-ol), for which each of R, R', and R" is CH.

In these shorthands, R, R', and R" represent substituents, alkyl or other attached, generally organic groups.

========,4,Alkyl chain variations in alcohols.

Short-chain alcohols have alkyl chains of 1–3 carbons.

Medium-chain alcohols have alkyl chains of 4–7 carbons.

Long-chain alcohols (also known as fatty alcohols) have alkyl chains of 8–21 carbons, and very long-chain alcohols have alkyl chains of 22 carbons or longer.

========,4,Simple alcohols.

"Simple alcohols" appears to be a completely undefined term.

However, simple alcohols are often referred to by common names derived by adding the word "alcohol" to the name of the appropriate alkyl group.

For instance, a chain consisting of one carbon (a methyl group, CH) with an OH group attached to the carbon is called "methyl alcohol" while a chain of two carbons (an ethyl group, CHCH) with an OH group connected to the CH is called "ethyl alcohol."

For more complex alcohols, the IUPAC nomenclature must be used.

Simple alcohols, in particular ethanol and methanol, possess denaturing and inert rendering properties, leading to their use as anti-microbial agents in medicine, pharmacy, and industry.

========,4,Higher alcohols.

Encyclopædia Britannica states, "The higher alcohols—those containing 4 to 10 carbon atoms—are somewhat viscous, or oily, and they have heavier fruity odours.

Some of the highly branched alcohols and many alcohols containing more than 12 carbon atoms are solids at room temperature."

Like ethanol, butanol can be produced by fermentation processes.

Saccharomyces yeast are known to produce these higher alcohols at temperatures above .

The bacterium "Clostridium acetobutylicum" can feed on cellulose to produce butanol on an industrial scale.

========,2,Applications.

Alcohol has a long history of several uses worldwide.

It is found in alcoholic beverages sold to adults, as fuel, and also has many scientific, medical, and industrial uses.

The term alcohol-free is often used to describe a product that does not contain alcohol.

========,3,Alcoholic beverages.

Alcoholic beverages, typically containing 3–40% ethanol by volume, have been produced and consumed by humans since pre-historic times.

Other alcohols such as 2-methyl-2-butanol (found in beer) and γ-hydroxybutyric acid (GHB) are also consumed by humans for their psychoactive effects.

========,3,Antiseptics.

Ethanol can be used as an antiseptic to disinfect the skin before injections are given, often along with iodine.

Ethanol-based soaps are becoming common in restaurants and are convenient because they do not require drying due to the volatility of the compound.

Alcohol based gels have become common as hand sanitizers.

========,3,Fuels.

Some alcohols, mainly ethanol and methanol, can be used as an alcohol fuel.

Fuel performance can be increased in forced induction internal combustion engines by injecting alcohol into the air intake after the turbocharger or supercharger has pressurized the air.

This cools the pressurized air, providing a denser air charge, which allows for more fuel, and therefore more power.

========,3,Solvents.

Hydroxyl groups (-OH), found in alcohols, are polar and therefore hydrophilic (water loving) but their carbon chain portion is non-polar which make them hydrophobic.

The molecule increasingly becomes overall more nonpolar and therefore less soluble in the polar water as the carbon chain becomes longer.

Methanol has the shortest carbon chain of all alcohols (one carbon atom) followed by ethanol (two carbon atoms.)

Alcohols have applications in industry and science as reagents or solvents.

Because of its relatively low toxicity compared with other alcohols and ability to dissolve non-polar substances, ethanol can be used as a solvent in medical drugs, perfumes, and vegetable essences such as vanilla.

In organic synthesis, alcohols serve as versatile intermediates.

========,2,Toxicity.

Ethanol is thought to cause harm partly as a result of direct damage to DNA caused by its metabolites.

Ethanol's toxicity is largely caused by its primary metabolite, acetaldehyde (systematically ethanal) and secondary metabolite, acetic acid.

Many primary alcohols are metabolized into aldehydes then to carboxylic acids whose toxicities are similar to acetaldehyde and acetic acid.

Metabolite toxicity is reduced in rats fed "N"-acetylcysteine and thiamine.

Although the mechanism is unclear, a meta-analysis of 572 studies have shown increased cancer risk from consumption of ethanol.

Tertiary alcohols cannot be metabolized into aldehydes and as a result they cause no hangover or toxicity through this mechanism.

Some secondary and tertiary alcohols are less poisonous than ethanol, because the liver is unable to metabolize them into toxic by-products.

This makes them more suitable for pharmaceutical use as the chronic harms are lower.

Ethchlorvynol and "tert"-amyl alcohol are tertiary alcohols which have seen both medicinal and recreational use.

Other alcohols are substantially more poisonous than ethanol, partly because they take much longer to be metabolized and partly because their metabolism produces substances that are even more toxic.

Methanol (wood alcohol), for instance, is oxidized to formaldehyde and then to the poisonous formic acid in the liver by alcohol dehydrogenase and formaldehyde dehydrogenase enzymes, respectively; accumulation of formic acid can lead to blindness or death.

Likewise, poisoning due to other alcohols such as ethylene glycol or diethylene glycol are due to their metabolites, which are also produced by alcohol dehydrogenase.

Methanol itself, while poisonous (LD 5628 mg/kg, oral, rat), has a much weaker sedative effect than ethanol.

Isopropyl alcohol is oxidized to form acetone by alcohol dehydrogenase in the liver, but has occasionally been abused by alcoholics, leading to a range of adverse health effects.

========,3,Treatment.

An effective treatment to prevent toxicity after methanol or ethylene glycol ingestion is to administer ethanol.

Alcohol dehydrogenase has a higher affinity for ethanol, thus preventing methanol from binding and acting as a substrate.

Any remaining methanol will then have time to be excreted through the kidneys.

========,2,Physical and chemical properties.

Alcohols have an odor that is often described as "biting" and as "hanging" in the nasal passages.

Ethanol has a slightly sweeter (or more fruit-like) odor than the other alcohols.

In general, the hydroxyl group makes the alcohol molecule polar.

Those groups can form hydrogen bonds to one another and to other compounds (except in certain large molecules where the hydroxyl is protected by steric hindrance of adjacent groups).

This hydrogen bonding means that alcohols can be used as protic solvents.

Two opposing solubility trends in alcohols are: the tendency of the polar OH to promote solubility in water, and the tendency of the carbon chain to resist it.

Thus, methanol, ethanol, and propanol are miscible in water because the hydroxyl group wins out over the short carbon chain.

Butanol, with a four-carbon chain, is moderately soluble because of a balance between the two trends.

Alcohols of five or more carbons such as pentanol and higher are effectively insoluble in water because of the hydrocarbon chain's dominance.

All simple alcohols are miscible in organic solvents.

Because of hydrogen bonding, alcohols tend to have higher boiling points than comparable hydrocarbons and ethers.

The boiling point of the alcohol ethanol is 78.29 °C, compared to 69 °C for the hydrocarbon hexane (a common constituent of gasoline), and 34.6 °C for diethyl ether.

Alcohols, like water, can show either acidic or basic properties at the -OH group.

With a pK of around 16-19, they are, in general, slightly weaker acids than water, but they are still able to react with strong bases such as sodium hydride or reactive metals such as sodium.

The salts that result are called alkoxides, with the general formula RO M. Meanwhile, the oxygen atom has lone pairs of nonbonded electrons that render it weakly basic in the presence of strong acids such as sulfuric acid.

For example, with methanol:

Alcohols can be oxidised to give aldehydes, ketones or carboxylic acids, or they can be dehydrated to alkenes.

They can react with carboxylic acids to form ester compounds, and they can (if activated first) undergo nucleophilic substitution reactions.

The lone pairs of electrons on the oxygen of the hydroxyl group also makes alcohols nucleophiles.

For more details, see the reactions of alcohols section below.

As one moves from primary to secondary to tertiary alcohols with the same backbone, the hydrogen bond strength, the boiling point, and the acidity typically decrease.

========,2,Occurrence in nature.

Ethanol occurs naturally as a byproduct of the metabolic process of yeast.

As such, ethanol will be present in any yeast habitat.

Ethanol can commonly be found in overripe fruit.

Methanol is produced naturally in the anaerobic metabolism of many varieties of bacteria, and is commonly present in small amounts in the environment.

Alcohols have been found outside the Solar System at low densities in star-forming regions of interstellar space.

========,2,Production.

========,3,Ziegler and oxo processes.

In the Ziegler process, linear alcohols are produced from ethylene and triethylaluminium followed by oxidation and hydrolysis.

An idealized synthesis of 1-octanol is shown:

The process generates a range of alcohols that are separated by distillation.

Many higher alcohols are produced by hydroformylation of alkenes followed by hydrogenation.

When applied to a terminal alkene, as is common, one typically obtains a linear alcohol:

Such processes give fatty alcohols, which are useful for detergents.

========,3,Hydration reactions.

Low molecular weight alcohols of industrial importance are produced by the addition of water to alkenes.

Ethanol, isopropanol, 2-butanol, and tert-butanol are produced by this general method.

Two implementations are employed, the direct and indirect methods.

The direct method avoids the formation of stable intermediates, typically using acid catalysts.