Pivalic acid
Encyclopedia
Pivalic acid is a carboxylic acid
Carboxylic acid
Carboxylic acids are organic acids characterized by the presence of at least one carboxyl group. The general formula of a carboxylic acid is R-COOH, where R is some monovalent functional group...

 with a molecular formula of (CH3)3CCO2H. This colourless, odiferous organic compound
Organic compound
An organic compound is any member of a large class of gaseous, liquid, or solid chemical compounds whose molecules contain carbon. For historical reasons discussed below, a few types of carbon-containing compounds such as carbides, carbonates, simple oxides of carbon, and cyanides, as well as the...

 is solid at room temperature.

Industrial route

Pivalic acid is prepared by “hydrocarboxylation” of isobutene via the Koch reaction
Koch reaction
The Koch reaction is an organic reaction for the organic synthesis of certain tertiary carboxylic acids from an alkene, carbon monoxide and water .This process is used on an industrial scale with annual production of 150.000 tons....

:2C=CH2 + CO + H2O → (CH3)3CCO2H
Such reactions require an acid catalyst such as hydrogen fluoride
Hydrogen fluoride
Hydrogen fluoride is a chemical compound with the formula HF. This colorless gas is the principal industrial source of fluorine, often in the aqueous form as hydrofluoric acid, and thus is the precursor to many important compounds including pharmaceuticals and polymers . HF is widely used in the...

. tert-Butyl alcohol
Tert-Butanol
tert-Butanol, or 2-methyl-2-propanol, is the simplest tertiary alcohol. It is one of the four isomers of butanol. tert-Butanol is a clear liquid with a camphor-like odor. It is very soluble in water and miscible with ethanol and diethyl ether...

 and isobutyl alcohol can also be used in place of isobutene. Globally, several million kilograms are produced annually.

Laboratory methods

It was originally prepared by the oxidation of pinacolone
Pinacolone
Pinacolone is an important ketone in organic chemistry. It has an odour reminiscent of peppermint and was discovered in 1866...

 with chromic acid
Chromic acid
The term chromic acid is usually used for a mixture made by adding concentrated sulfuric acid to a dichromate, which may contain a variety of compounds, including solid chromium trioxide. This kind of chromic acid may be used as a cleaning mixture for glass. Chromic acid may also refer to the...

 and by the hydrolysis of tert-butyl cyanide
Pivalonitrile
Pivalonitrile is a nitrile with the semi-structural formula 3CCN, abbreviated t-BuCN. This aliphatic organic compound is a clear, colourless liquid that is used as a solvent and as a labile ligand in coordination chemistry. Pivalonitrile is isomeric with tert-butyl isocyanide....

. Convenient laboratory routes proceed via t-butyl chloride via carbonation of the Grignard reagent and by oxidation of pinacalone.

Applications

Relative to esters of most carboxylic acids, ester
Ester
Esters are chemical compounds derived by reacting an oxoacid with a hydroxyl compound such as an alcohol or phenol. Esters are usually derived from an inorganic acid or organic acid in which at least one -OH group is replaced by an -O-alkyl group, and most commonly from carboxylic acids and...

s of pivalic acid are unusually resistant to hydrolysis. Some applications result from this thermal stability. Polymers derived from pivalate esters of vinyl alcohol are highly reflective lacquers. The pivaloyl (abbreviated piv or pv) group is a protective group for alcohol
Alcohol
In chemistry, an alcohol is an organic compound in which the hydroxy functional group is bound to a carbon atom. In particular, this carbon center should be saturated, having single bonds to three other atoms....

s in organic synthesis
Organic synthesis
Organic synthesis is a special branch of chemical synthesis and is concerned with the construction of organic compounds via organic reactions. Organic molecules can often contain a higher level of complexity compared to purely inorganic compounds, so the synthesis of organic compounds has...

.

Safety

Like most carboxylic acids pivalic acid is a mild irritant and only weakly toxic (oral = 900 mg/kg for rats).
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