Phenol-Catalyzed Thione-Thiol Rearrangement of Xanthates and Modified Intermediate Neglect of Differential Overlap(MINDO/3) Analysis of the Reaction Mechanism.
作者:Kazunobu HARANO、Hideo KIYONAGA、Takuzo HISANO
DOI:10.1248/cpb.40.2654
日期:——
S-Alkyl dithiocarbonates (xanthates) of alkanols containing strained σ bonds underwent rearrangement to S, S-dialkyl dithiocarbonates, catalyzed by phenolic compounds. The reaction followed first-order kinetics and the rates were affected by the acidity of the phenols. The rate contants are proportional to the square of the concentration of phenol.The modified intermediate neglect of differential overlap (MINDO/3) geometry optimization indicates that S, S-dialkyl dithiocarbonate is ca. 9 kcal/mol more stable than O, S-dialkyl xanthate. The thione-thiol rearrangement and sulfide formation reactions were analyzed by MO simulations. The experimental results can be well reproduced by the MINDO/3 method rather than the modified neglect of diatomic overlap (MNDO) method. Based on these data, the reaction mechanism is discussed.
含有σ键的烷醇的S-烷基二硫代碳酸酯(黄药)在酚类化合物的催化下发生重排,生成S,S-二烷基二硫代碳酸酯。该反应遵循一级动力学,速率受酚类化合物的酸度影响。速率常数与酚类化合物浓度的平方成正比。对忽略差分重叠(MINDO/3)几何优化的修正中间体表明,S,S-二烷基二硫代碳酸酯比O,S-二烷基黄药稳定约9 kcal/mol。硫醇-硫醚重排和硫化物形成反应通过MO模拟进行了分析。实验结果可以通过MINDO/3方法而不是修正的忽略二原子重叠(MNDO)方法很好地再现。基于这些数据,讨论了反应机理。