Benzhydryltrimethylammonium hydroxide

The decomposition of benzhydryltrimethylammonium hydroxide (Equation 4.5), on the other hand, according to Ingold, proceeds by initial slow formation of the relatively stable diphenylmethyl carbocation5 and subsequent fast attack on the carbocation by hydroxide. Because hydroxide, is not part of the activated complex of the slow step of this reaction, it does not enter into the rate equation. 

Although the Sommelet rearrangement 1S8> product 29 was initially reported in the decomposition of benzhydryltrimethylammonium hydroxide, 28, the major products result from displacement reactions 71>. Hughes and Ingold 71> studied the decomposition of benzhydryltrimethylammonium hydroxide as a function of concentration. 

In 1933 the two still widely accepted mechanisms for nucleophilic displacement reactions were proposed by Hughes, Ingold, and Patel.4 They found that decomposition of quartenary ammonium salts, R4N+Y, to give R3N and RY exhibited two different kinds of kinetic behavior depending on the ammonium salt used. For example, when methyl alcohol was formed from trimethyl-n-decylammonium hydroxide (Equation 4.3), the rate of formation of methyl alcohol was found to be second-order, first-order each in trimethyl-n-decylam-monium cation and in hydroxide ion as in Equation 4.4. On the other hand, the rate of formation of diphenylmethanol from benzhydryltrimethylammonium... 

In 1937, Marcel Sommelet resumed investigations started in the early 1920s. Having heated benzhydryltrimethylammonium bromide with aqueous sodium hydroxide, he isolated as the sole product [(o-benzyl)benzyl]dimethylamine. " Obviously this product cannot have emanated from trimethylamine diphenylmethylide (338a) but resulted from the structural reorganization of the less stable isomeric ylide 338b (Scheme 1-264). 

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