Date of Award
Bachelor of Science
This thesis examines the synthesis of two sterically hindered diesters, neopentyl glycol dipivaloate and ditert-butyl 2, 2-diethylmalonate. The implications of this hinderance for hydrolysis in basic medium are discussed. The neopentyl glycol diester of 2,2-dimethylpropanoic acid is prepared with little difficulty by reaction of the glycol with the acid chloride in the presence of pyridine. The process gives the desired ester in approximately 66% yield. The preparation of the ditert-butyl ester of diethylmalonic acid is also attempted by means of the acid chloride in the presence of pyridine. Preparation of the diethylmalonyl dichloride using acetonitrile as a solvent in most cases resulted in a drastically reduced yield due to what we attribute to the formation of substituted pyrimidines. By using cyclohexane, the desired acid chloride was able to be isolated in appreciable amounts. In both solvents, 2-ethylbutanoyl chloride is also obtained. Reaction of the 2-ethylbutanoyl chloride with tert-butanol in the presence of pyridine gives tert-butyl 2-ethylbutanoate in 44% yield. Ditert-butyl 2,3-diethylmalonate is not isolated after a similar reaction of diethylmalonyl dichloride with tert-butanol. However, spectroscopic evidence suggests that a small amount of the acid chloride of tert-butyl hydrogen 2, 2-diethylmalonate is isolated from the product mixture. The reactivity of this particular acid chloride appears atypically low for an aliphatic acid chloride, and this is explained by its large steric hindrance. Preparation of the two hindered esters of this study by methods which utilize both the dicarboxylic acid chloride and the glycol would immediately suggest a feasible synthetic method for the preparation of the mixed polyester. On the basis of others' work, such a product would be suspected of being particularly resistant to basic hydrolysis.
Bankowitz, Richard A., "Synthesis of sterically hindered disasters" (1979). Honors Theses. 1868.