A comparison of the velocities of hydrolysis of the 2-, the 3- and the 4-methyl diphenyl ketimine hydrochlorides, in which the velocity of the first is very much slower than either of the other two, suggests steric hindrance. The very slow rate of hydrolysis of 2, 4, 6-trihydroxy diphenyl ketimine hydrochloride has been reported by one of us. This slow rate may be accounted for on the basis of the multiple opportunities for tautomerism involving the very stable enamine forms. We have recently found 2-methyl, 4, 6-dihydroxy di phenyl (orcinyl phenyl) ketimine hydrochloride to be even more slowly hydrolyzed. It would appear here that the steric hindrance effect outweighs the possible enamine tautomerism
