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Experimental and computational studies of the mechanism of base‐catalyzed ring opening of 2‐(chloromethyl)oxirane by benzoic acid
Author(s) -
Bespalko Yuliia,
Sinel'nikova Marina,
Shved Elena,
Bakhalova Evgeniia
Publication year - 2021
Publication title -
international journal of chemical kinetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.341
H-Index - 68
eISSN - 1097-4601
pISSN - 0538-8066
DOI - 10.1002/kin.21448
Subject(s) - chemistry , benzoic acid , nucleophile , ring (chemistry) , regioselectivity , reagent , catalysis , reaction mechanism , base (topology) , solvent , solvent effects , reaction rate constant , density functional theory , medicinal chemistry , rate determining step , kinetics , computational chemistry , organic chemistry , mathematical analysis , physics , mathematics , quantum mechanics
Using methods of chemical kinetics and quantum modeling, we investigated the mechanism by which base catalysts affect the regioselectivity of the ring opening of 2‐(chloromethyl)oxirane by benzoic acid. The model reaction was carried out using 2‐(chloromethyl)oxirane as both reagent and solvent at temperatures of 303‐333 K. Rate constants and activation parameters of the ring opening were determined for the overall reaction and for the formation of the isomeric “normal” and “abnormal” products. Density functional theory B3LYP/6‐31+G** was used to examine possible reaction pathways. A comparison of experimental measurements and theoretical calculations confirm that the rate‐limiting step is the attack of the benzoate anion on the C 1 and C 2 positions of 2‐(chloromethyl)oxirane. The present results indicate that the regioselectivity of the 2‐(chloromethyl)oxirane ring opening by benzoic acid depends on the ratio of A2 mechanisms, S N 2 and “borderline” S N 2 type. This suggests that weak nucleophilic base catalysts can increase the reaction regiospecificity by increasing the contribution of the S N 2 pathway.