1976 Volume 49 Issue 12 Pages 3574-3577
Phenylcarbamoyl cyanide (1), under thermal conditions or base-catalysis, behaves as a source of bothphenyl isocyanate and hydrogen cyanide in the syntheses of carbamates, cyanohydrins, and iminohydantoins. The reaction mechanism of 1 with methanol in the presence of tertiary amine was investigated. The following observations (i–iii) led us to deduce that phenyl isocyanate was not involved as the intermediate and that the rate-determining step involves nucleophilic displacement of 1 by the alkoxyl group, reinforced by the base: (i) the N–H exchange was too fast to be rate-determining; (ii) d-labelling experiments showed kH/kD=1.8–1.9 in any of the reactions, 1-d1+MeOH, 1-d0+MeOD, and 1-d1+MeOD, and (iii) diphenylcarbamoyl cyanide reacted only 7.2 times slower than did 1.
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