Abstract

The trialkylacetic acids, carboxylic acids with three alkyl groups on the alpha-carbon, have been manufactured in the United States and Europe since the early 1960s. They are offered commercially by Exxon as neo acids and by Shell as Versatic Acids. The principal commercial products are the C₅ acid and the C₁₀ acid, although smaller quantities of other carbon number acids are also produced.

The C₅ acid, 2,2-dimethylpropionic acid, also referred to as neopentanoic acid and as pivalic acid, is a solid at room temperature and undergoes reactions typical of carboxylic acids, such as formation of the acid chloride, esterification, reduction. Because of steric hindrance of the carbonyl group, reactions often proceed less readily than with straight chain acids, but once formed derivatives of neopentanoic acid are typically more resistant to hydrolysis and oxidation.

Neopentanoic acid is manufactured using variants of the Koch reaction, in which a strong acid catalyst is used in the reaction of olefin, carbon monoxide and water. Production worldwide is estimated at 15 thousand metric tons per year. Neopentanoic acid finds numerous uses in the production of polymers and resins, pharmaceuticals, agricultural chemicals, cosmetics, fuels, lubricants and transmission fluids.

The C₁₀ trialkylacetic acid, also known as neodecanoic acid and as Versatic 10, is a mixture of isomers, resulting in a material that is a liquid at room temperature. This acid undergoes the same reactions as neopentanoic acid, such as acid chloride formation and esterification. In addition, neodecanoic acid finds a large commercial use in the preparation of metal salts. The manufacturing process is the same as that used for neopentanoic acid. Production volumes of the C₁₀ acid are estimated at tens of thousands of metric tons per year.

Neodecanoic acid is used in a number of applications, including polymers, resins and coatings, adhesion promoters, metal-working fluids, hydraulic fluids, metal-extraction, fuels, lubricants, and electrical/electronic applications. Significant derivatives of neoacids include the glycidyl and vinyl esters. The glycidyl esters are manufactured by both Exxon and Shell, and are used as intermediates for the production of alkyds and acrylics, and as a reactive diluent for epoxy resins. The vinyl esters, manufactured by Shell, are used primarily in coatings, but also in construction, adhesives, cosmetics, and in a number of miscellaneous areas.