Trimethylacetic Acid from Pinacolone

The general plan of Organic Syntheses has been discussed in the prefaces of the previous volumes. In this volume are published two distinctly different methods of preparation for each of two compounds. The directions for producing /3-chloro-propionic acid first from acrolein and second from trimethylene chlorohydrin, and for producing trimethylacetic acid first from terJ-butyl chloride and second from pinacolone, have been included. This has been deemed advisable since in some countries one raw material is more readily available than the other. 

Cleavage of ketones by oxidation is infrequently used for preparation of monocarboxylic acids. Trimethylacetic acid is made in 75% yield from pinacolone, (CHj)jCCOCHj, by oxidation with chromic anhydride in aqueous acetic acid. Cleavage on only one side of the carbonyl group is possible in this case. 

An oxidizable alkyl group is not necessarily attached to an aromatic nucleus. Oxidation of a methyl group of trimethylacetic acid by heating for 7 hours with alkaline permanganate gives dimethylmaIonic acid (35%). Other examples include the a-keto acids, trimethylpyruvic acid (40%) ° from pinacolone and /3-naphthylglyoxylic acid (40%) from -acetyl-naphthalene. 

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