Transesterification of soybean oil (SBO) and other triglycerides with alcohols, in the presence of a catalyst, yields fatty esters and glycerol. Di‐ and monoglycerides are intermediates. Reactions are consecutive and reversible. Rate constants have been determined for each reaction with a computerized kinetic program. The effects of the type of alcohol, 1‐butanol or methanol (MeOH); molar ratio of alcohol to SBO; type and amount of catalyst; and reaction temperature on rate constants and kinetic order were examined. Forward reactions appear to be pseudo‐first order or second order depending upon conditions used. Reverse reactions appear to be second order. At a molar ratio of MeOH/SBO of 6:1, a shunt reaction was observed. Energy of activation was determined for all forward and reverse reactions under a variety of experimental conditions from plots of log k vs 1/T. Values ranged from 8–20 kcal/mol.

9(10)-Carboxystearic acid and its mono-and dimethyl esters were esterified and transesterified with 1-butanol, 2-me thoxyethanol, 2-chloroethanol, 2,2-dimethylpentanol, 2-ethylhexanol and 1-octanol. Rate studies for the sulfuric acid-catalyzed esterification of 9(10)-carboxystearic acid to alkyl 9(10)-carboxystearate and alkyl 9(10)-carboalkoxystearate indicate than on an average the terminal carboxyl is approximately 26-27 times more reactive than the branched carboxyl group. Esterification is highly dependent on catalyst concentration. Steric hindrance in 2,2-dimethylpentanol and the electrophilic character of 2-methoxyethanol and 2-chloroethanol markedly retard the rate. In addition to the expected diesters, 2-chloroethanol yields esters containing extra -O-CH2CH 2-groups, The rate of transesterification of the terminal ester group of mono-and lpresented at the AOCS Meeting, Atlantic City, October 1971. 2N. Market. Nutr. Res. Div., ARS, USDA. 91101 I C00--COO--D \ ] t 1 0 4 8 12 lime, M~n. C E 1 t 16 20 24FIG. 1. Gas chromatogram of (A) methyl stearate (reference compound); (B) methyl 9(10)-carbomethoxystearate; (C) methyl 9(10)-carbo(dimethylpentoxy)stearate; (D) dimethylpentyl 9(10)-carbomethoxystearate; (E) dimethylpentyl 9(10)-carbo(dimethylpentoxy)stearate. 302 dimethyt esters of 9(10)-carboxystearic acid is about two times faster than the rate of esterification of the branched carboxyl group. Transesterification of the branched 9( t0)-ester group is extremely slow.

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