The effects of structural changes in NN-dialkylcarbamoyl chlorides and in some hydroxylic compounds as solvolytic agents, of solvent polarity, and of the kinetic mass-law, on the rates of solvolyses have been studied. The pseudounimolecular constants are enhanced by the increase of the electron-releasing effects of N-alkyl groups as well as by increasing solvent polarity, and are sensitive to the presence of chloride ions. These results are in agreement with the assumption of the unimolecular mechanism in all cases. The isokinetic relationships suggest two interaction mechanisms by solvation of the transition states.' Traian Vuia ', Timisoara, P.O.B. 103, Romania CARBONIC ACID CHLORIDES, as a particular kind of acyl chlorides, show interesting features in nucleophilic substitution mechanisms, e.g. the reactions of ethyl chloroformate with substituted anilines and hydrolyses of substituted aryl chloroformates.2 Although the solvolysis of alkyl chloroformates has been widely investigated, only a few studies of the reactions of NNdialkylcarbamoyl chlorides have been reported. Hall 394 has demonstrated the unimolecular mechanism of hydrolysis of NN-dimethylcarbamoyl chloride in waterdioxan (86.1% v/v) on the basis of the kinetic mass-law effect of the chloride ion, the insensivity of the reaction rate to strong nucleophiles (such as the hydroxide ion, pyrrolidine, or hydroxylamine), the activation parameters, and the catalytic action of Hg++ ions. This mechanism has been confirmed for the hydrolysis of NN-di-isopropylcarbamoyl and NN-pentamethylenecarbamoyl chlorides in water-acetone (10.9% v/v) and for NN-dimethylcarbamoyl chloride in water.6Hall has suggested a bimolecular mechanism for the reactions of NN-dimethylcarbamoyl chloride with aliphatic amines.' RESULTS Kinetics were followed by direct conductonietric measurements. The pseudo-first-order rate constants for the c O t -2 -'I
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