Kinetics and Mechanism of the Aminolysis of Aryl N-Benzyl Thiocarbamates in Acetonitrile

作者：Oh Hyuck Keun^*

来源：Bulletin of the Korean Chemical Society, 2011, 32(1): 137-140.

DOI：10.5012/bkcs.2011.32.1.137

• Nucleophilic substitution
• Aryl N-benzyl thiocarbamates
• Cross-interaction constant
• Kinetic isotope effects
• Concerted mechanism

The aminolysis reactions of phenyl N-benzyl thiocarbamate with benzylamines in acetonitrile at 50.0 degrees C are investigated. The reactions are first order in both the amine and the substrate. Under amine excess, pseudo-first coefficient (k(obs)) are obtained, plot of k(obs) vs free amine concentration are linear. The signs of rho(xz) (< 0) are consistent with concerted mechanism. Moreover, the variations of rho(x) and rho(z) with respect to the sustituent in the substrate and large rho(xz) value indicate that the reactions proceed concerted mechanism. The normal kinetic isotope effects (k(H)/k(D) = 1.3 similar to 1.5) involving deuterated benzylamine nucleophiles suggest a hydrogen-bonded, four-centered-type transition state. The activation parameters, Delta R double dagger and Delta S double dagger, are consistent with this transition state structure.

• 出版日期2011-1-20