Kinetics and mechanism of aminolysis of aryl cyclobutanecarboxylates in acetonitrile

Kinetics and Mechanism of Triethylamine Catalysed Michael Addition of Benzenethiol to 1-(2-Nitrovinyl)benzene in Acetonitrile

“…Whenever bond formation occurs in the transition state ρ xy is negative, 4 whereas for bond breaking in transition state ρ xy is found to be positive. 22,23 A cyclic transition state with bond formation has been envisaged on the basis of sign and magnitude of ρ xy values (−0.24 to −0.90) in the addition reaction of benzylamine to activated olefins. In contrast, the aminolysis of thiophenyl acetates with benzylamines in acetonitrile which is believed to proceed by rate-limiting expulsion of leaving group, gives positive ρ xy (0.90) value.…”

Kinetics and Mechanism of the Pyridinolysis of Aryl Cyclobutanecarboxylates in Acetonitrile

“…6 We have found that the reactions of aryl cyclopropancarboxylates 5 and the aryl cyclobutanecarboxylates 6 proceed through a stepwise mechanism with late-limiting expulsion of a leaving group (aryl oxides) from a tetrahedral intermediate, T…”

“…5,6,8b,9 In previous work, we investigated the effect on the mechanism of the reaction of a cyclobutane group, RY = cyclo-C 4 H 7 , with benzylamines in acetonitrile (6) and found that the cyclobutyl group leads to stepwise aminolysis with rate-limiting breakdown of the intermediate, T ± . In this paper, we extend our work to the pyridinolysis of aryl cyclobutanecarboxylates, II, with pyridines (Py) in acetonitrile (eq.…”

Kinetics and Mechanism of the Aminolysis of Thiophenyl Cyclohexanecarboxylates

“…(1), where X, Y and Z are the substituents in the nucleophile, substrate and leaving group, respectively. Such rate-limiting breakdown of T ± has been reported, for example, in the reactions of methyl chloroformate with pyridines, 1 substituted diphenyl carbonates with quinuclidine, 2 2,4-dinitrophenyl acetate and methyl carbonate with pyridines, 3 aryl cyclobutanecarboxylate with benxylamines, 4 O-2,4-dinitrophenyl Thionobenzoate with pyridines, 5 S-2,4-dinitophenyl thiobenzoate with pyridines, 6 phenyl benzoate with piperidines 7 and thiophenyl cyclobutanecarboxylate with benzylamines reaction path. 8 Based on the results of these experimental studies, we were able to determine the signs of the cross-interaction constants, ρij in eq.…”

“…In this type of reaction, a non-linear Brönsted-type plot showing a break from a large (β = 0.8 -1.0) to a small (β = 0.1 -0.3) rate dependence on basicity of the attacking amine is often obtained at pKo as the basicity of nucleophile is increased. [1][2][3][4][5][6][7][8] The break at pKo where k-1 = k2 has been attributed to a change in the rate-determining step from breakdown (k2) to formation (k1) of a tetrahedral intermediate, T ± , in the reaction path, [1][2][3][4][5][6][7][8] eq. (1), where X, Y and Z are the substituents in the nucleophile, substrate and leaving group, respectively.…”