Product-Rate Correlations for Solvolyses of 2,4-Dimethoxybenzenesulfonyl Chloride

Bulletin of the Korean chemical society

In Sun Koo¹  Hojune Choi¹  Han Joong Koh¹  Jong Keun Park¹  Soo Ryeon Kim¹ 

关键词: Extended Grunwald-Winstein equation;    SN2 mechanism;    Solvent kinetic isotope effect;    Product selectivity;    Third-order rate constant;   

DOI  :  

学科分类：化学（综合）

来源: Korean Chemical Society

【 摘 要 】

The solvolysis rate constants of 2,4-dimethoxybenzenesulfonyl chloride (1) in 30 different solvents are well correlated with the extended Grunwald-Winstein equation, using the NT solvent nucleophilicity scale and YCl solvent ionizing scale, with sensitivity values of 0.93 ± 0.14 and 0.65 ± 0.06 for l and m, respectively. These l and m values can be considered to support a SN2 reaction pathway. The activation enthalpies (H ) were 12.4 to 14.6 kcal·mol1 and the activation entropies (S) were 15.5 to 32.3 cal·mol1·K1, which is consistent with the proposed bimolecular reaction mechanism. The solvent kinetic isotope effects (SKIE) were 1.74 to 1.86, which is also in accord with the SN2 mechanism and was possibly assisted using a general-base catalysis. The values of product selectivity (S) for solvolyses of 1 in alcohol/water mixtures was 0.57 to 6.5, which is also consistent with the proposed bimolecular reaction mechanism. Third-order rate constants, kww and kaa, were calculated from the rate constants (kobs), together with kaw and kwa calculated from the intercept and slope of the plot of 1/S vs. [water]/[alcohol]. The calculated rate constants, kcalc (kww, kaw, kwa and kaa), are in satisfactory agreement with the experimental values, supporting the stoichiometric solvation effect analysis.

【 授权许可】

Unknown