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facilitation of hydrolysis attributable to the 6-methyl and 6-chloro groups in this series.Methyl 2-Formyl, 2-Acetyl-, and 2-Benzoylbenzoates. In the three unsubstituted esters, methyl o-formylbenzoate (111)) methyl o-acetylbenzoate (11)) and methyl o-benzoylbenzoate (I), the alkaline hydrolysis may conceivably proceed via two mechanisms: (1) attack of hydroxide ion at the carbonyl function as in the case of the 6-substituted esters, and (2) the normal attack of the hydroxide ion at the carbomethoxy function. Since Bender has shown that I11 hydrolyzes lo5 faster than methyl p-formylbenzoate the main path undoubtedly involves carbonyl attack.With the unsubstituted benzoyl esters the situation is reversed. Methyl pbenzoylbenzoate hydrolyzes 1.46 times faster than I. Thus attack of hydroxide ion on the carbomethoxy group may be the rate-controlling step for I.The rate of hydrolysis of I1 is intermediate between that of I11 and I. Since I1 and I11 hydrolyze at so much greater rates than does I, the rate-controlling step may be the forward reaction in eq 1. Unfortunately, we have been unable to find a comparative study involving benzophenone, acetopheone, and benzaldehyde in order to estimate the relative rates of such a reaction.Although we were unable to prepare pure samples of the normal methyl esters of 6-methyl-and 6-chloro-2-formylbenzoic acids, mixtures of normal and pseudo esters were obtained. Qualitative tests showed that these esters hydrolyzed more rapidly than did methyl 2-formylbenzoate, but the rates were so rapid that further kinetic work on the ester mixtures was not done. Thus, a steric effect to accelerate the hydrolyses is probably present in these cases also but further work is required before a suitable system for measurement can be found.Acknowledgment. We thank Professor Jack Hine for valuable discussion concerning the kinetic results. (31) M. L. Bender, J. A. Reinstein, M. S. Silver, and R. Mikulak, J . Am. Chem. SOC., 81, 4545 (1965). Methyl 2-Formylbenzoates.serve similar functions, namely, to keep the ester carbonyl group out of the plane of the ring to which it is attached. This nonplanarity facilitates the intramolecular nucleophilic attack of the neighboring 0-function in two ways: (a) there is a more favorable orientation,3 and (b) the carbonyl group carbon of the ester is more electrophilic since there is less distribution of positive charge to the aryl ring. The fact that VI1 hydrolyzes appreciably faster than IV is explained by the greater inductive effect of C1 as compared to CHI on both K and kl, since the steric effect of each should be about the same. 30Methyl 2-Acetylbenzoates. In this series the rates for V and VI11 are also greater than that for the unsubstituted ester I1 but the rate ratios for V (1.4) and VI1(7.4) as compared to I1 are appreciably less than the ratios for IV (4.3) and VI1 (32.2) as compared to I. The steric explanation for the rate increase is similar to that described for the methyl 2-benzoylbenzoates. However, the fact that there is a greater increase in r...

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