Tert-Butanol

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Tert-Butanol

tert-Butanol, or 2-methyl-2-propanol (colourless liquid or white solid, depending on the ambient temperature), is the simplest tertiary alcohol
Alcohol

In chemistry, an alcohol is any organic compound in which a hydroxyl Functional group is bound to a carbon atom of an alkyl or substituted alkyl group....
. It is one of the four isomers of butanol
Butanol

Butanol or butyl alcohol , is a primary alcohol with a 4 carbon structure and the molecular formula of Carbon4Hydrogen9Oxygen....
. tert-Butanol is a clear liquid with a camphor
Camphor

Camphor is a waxy, white or transparent solid with a strong, aromatic odor. It is a terpenoid with the chemical formula carbon10hydrogen16oxygen....
-like odor. It is very soluble in water and miscible with ethanol
Ethanol

Ethanol, also called ethyl alcohol, pure alcohol, grain alcohol, or drinking alcohol, is a volatility , flammable, colorless liquid....
and diethyl ether
Diethyl ether

Diethyl ether, also known as ether and ethoxyethane, is a clear, colorless, and highly flammable liquid with a low boiling point and a characteristic odor....
. It is unique among the isomers of butanol because it tends to be a solid at room temperature, with a melting point slightly above 25 °C.

tert-Butanol can be manufactured industrially by the catalytic hydration
Hydration reaction

In organic chemistry, a hydration reaction is a chemical reaction in which a hydroxyl group and a hydrogen cation are added to the two carbon atoms covalent bonded together in the carbon-carbon double bond which makes up an alkene functional group....
of isobutylene
Isobutylene

Isobutylene is a hydrocarbon of significant industrial importance. It is a four-carbon branched alkene , one of the four isomers of butylene. At standard temperature and pressure it is a colorless flammable gas....
.

tert-Butanol is used as a solvent, as a denaturant for ethanol, as an ingredient in paint removers, as an octane
Octane rating

The octane rating is a measure of the resistance of gasoline and other fuels to detonation in spark plug internal combustion engines. High-performance engines typically have higher compression ratios and are therefore more prone to detonation, so they require higher octane fuel....
booster for gasoline
Gasoline

File:GasCan.jpgGasoline or petrol is a petroleum-derived liquid mixture, primarily used as fuel in internal combustion engines.It consists mostly of aliphatic hydrocarbons, enhanced with iso-octane or the aromatic hydrocarbons toluene and benzene to increase its octane rating....
, as an oxygenate
Oxygenate

Oxygenated chemical compounds contain oxygen as a part of their chemical structure. The term usually refers to oxygenated fuels. Oxygenates are usually employed as gasoline additives to reduce carbon monoxide that is created during the burning of the fuel....
gasoline additive
Gasoline additive

Gasoline additives increase gasoline's octane rating or act as corrosion inhibitors or lubricant, thus allowing the use of higher compression ratios for greater efficiency and power, however some carry heavy environmental risks....
, and as an intermediate in the synthesis of other chemical commodities such as MTBE, ETBE
ETBE

Ethyl tert-butyl ether is commonly used as an oxygenate gasoline additive in the production of gasoline from crude oil. ETBE offers equal or greater air quality benefits as ethanol, while being technically and logistically less challenging....
, TBHP, other flavors and perfumes.

tertiary alcohol, tert-butanol is more stable to oxidation and less reactive than the other isomers of butanol.

When tert-butanol is deprotonated with a strong base
Base (chemistry)

In chemistry, a base is most commonly thought of as an aqueous substance that can accept protons. A base is also often referred to as an alkali if OH- ions are involved....
, the product is an alkoxide
Alkoxide

An alkoxide is the conjugate base of an alcohol and therefore consists of an organic group bonded to a negatively charged oxygen atom. They can be written as RO–, where R is the organic substituent....
anion.

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Encyclopedia

tert-Butanol, or 2-methyl-2-propanol (colourless liquid or white solid, depending on the ambient temperature), is the simplest tertiary alcohol
Alcohol

In chemistry, an alcohol is any organic compound in which a hydroxyl Functional group is bound to a carbon atom of an alkyl or substituted alkyl group....
. It is one of the four isomers of butanol
Butanol

Butanol or butyl alcohol , is a primary alcohol with a 4 carbon structure and the molecular formula of Carbon4Hydrogen9Oxygen....
. tert-Butanol is a clear liquid with a camphor
Camphor

Camphor is a waxy, white or transparent solid with a strong, aromatic odor. It is a terpenoid with the chemical formula carbon10hydrogen16oxygen....
-like odor. It is very soluble in water and miscible with ethanol
Ethanol

Ethanol, also called ethyl alcohol, pure alcohol, grain alcohol, or drinking alcohol, is a volatility , flammable, colorless liquid....
and diethyl ether
Diethyl ether

Diethyl ether, also known as ether and ethoxyethane, is a clear, colorless, and highly flammable liquid with a low boiling point and a characteristic odor....
. It is unique among the isomers of butanol because it tends to be a solid at room temperature, with a melting point slightly above 25 °C.

Preparation
tert-Butanol can be manufactured industrially by the catalytic hydration
Hydration reaction

In organic chemistry, a hydration reaction is a chemical reaction in which a hydroxyl group and a hydrogen cation are added to the two carbon atoms covalent bonded together in the carbon-carbon double bond which makes up an alkene functional group....
of isobutylene
Isobutylene

Isobutylene is a hydrocarbon of significant industrial importance. It is a four-carbon branched alkene , one of the four isomers of butylene. At standard temperature and pressure it is a colorless flammable gas....
.

Applications
tert-Butanol is used as a solvent, as a denaturant for ethanol, as an ingredient in paint removers, as an octane
Octane rating

The octane rating is a measure of the resistance of gasoline and other fuels to detonation in spark plug internal combustion engines. High-performance engines typically have higher compression ratios and are therefore more prone to detonation, so they require higher octane fuel....
booster for gasoline
Gasoline

File:GasCan.jpgGasoline or petrol is a petroleum-derived liquid mixture, primarily used as fuel in internal combustion engines.It consists mostly of aliphatic hydrocarbons, enhanced with iso-octane or the aromatic hydrocarbons toluene and benzene to increase its octane rating....
, as an oxygenate
Oxygenate

Oxygenated chemical compounds contain oxygen as a part of their chemical structure. The term usually refers to oxygenated fuels. Oxygenates are usually employed as gasoline additives to reduce carbon monoxide that is created during the burning of the fuel....
gasoline additive
Gasoline additive

Gasoline additives increase gasoline's octane rating or act as corrosion inhibitors or lubricant, thus allowing the use of higher compression ratios for greater efficiency and power, however some carry heavy environmental risks....
, and as an intermediate in the synthesis of other chemical commodities such as MTBE, ETBE
ETBE

Ethyl tert-butyl ether is commonly used as an oxygenate gasoline additive in the production of gasoline from crude oil. ETBE offers equal or greater air quality benefits as ethanol, while being technically and logistically less challenging....
, TBHP, other flavors and perfumes.

Chemistry
As a tertiary alcohol, tert-butanol is more stable to oxidation and less reactive than the other isomers of butanol.

When tert-butanol is deprotonated with a strong base
Base (chemistry)

In chemistry, a base is most commonly thought of as an aqueous substance that can accept protons. A base is also often referred to as an alkali if OH- ions are involved....
, the product is an alkoxide
Alkoxide

An alkoxide is the conjugate base of an alcohol and therefore consists of an organic group bonded to a negatively charged oxygen atom. They can be written as RO–, where R is the organic substituent....
anion. In this case, it is tert-butoxide. For example, the commonly used organic reagent potassium tert-butoxide
Potassium tert-butoxide

Potassium tert-butoxide is the chemical compound with the chemical formula 3COK. This colourless solid is a strong base useful in organic synthesis....
is prepared by refluxing dry tert-butanol with potassium
Potassium

Potassium is a chemical element. It has the symbol K , atomic number 19, and atomic mass 39.0983. Potassium was first isolated from potash, hence the name....
metal.

K + tBuOH ? tBuO^-K⁺ + ¹/₂ H₂

The tert-butoxide species is itself useful as a strong, non-nucleophilic base in organic chemistry. It is able to abstract acidic protons from the substrate molecule readily, but its steric bulk inhibits the group from participating in nucleophilic substitution, such as in a Williamson ether synthesis
Williamson ether synthesis

The Williamson ether synthesis is an organic reaction, forming an ether from a organohalide and an alcohol. This reaction was developed by Alexander William Williamson in 1850 ....
or an S_N2 reaction.

Conversion to alkyl halide
tert-Butanol (also tert-butyl alcohol) reacts with hydrogen chloride
Hydrogen chloride

The Chemical compound hydrogen chloride has the chemical formula HydrogenChlorine. At room temperature, it is a colorless gas, which forms white fumes of hydrochloric acid upon contact with atmospheric humidity....
to form tert-butyl chloride and water via an S_N1 mechanism.

Step 1
Step 2
Step 3

The overall reaction, therefore, is:

Because tert-butanol is a tertiary alcohol, the relative stability of the tert-butyl carbocation in the Step 2 allows the S_N1 mechanism to be followed. Primary alcohols generally require an S_N2 mechanism because the energy barrier to produce a primary carbocation is so high that it will not reasonably happen. Tert-butanol is an exception because the bulky isobutyl moiety stabilizes the carbocation. The S_N2 mechanism allows the carbocation intermediate to be avoided.