應用分光光度法研究了有機溶劑中米氏碱的2,3,5,6-四溴-對苯醌氧化反應的動力學與反應機理,以及反應的溶劑效應與壓力效應.结果表明:该反應是對每種反應物均爲一级的二级反應,爲包含電荷轉移復合物中間體的電子-質子-電子轉移的多步反應.該反應的活化體積爲-34cm3·mol-1,顯示從反應物到過渡態體系的極性增加较大.不同溶劑中的反應速率大小依次爲二氯甲烷,乙氫,丙酮.以N,N-甲基-對甲苯胺爲模型物,從械理上探讨了産生溶劑效應與壓力效應相异的原因.%The kinetics of oxidation of Michler's Hydride with 2, 3, 5,6-tetrabromo-p-benzoquinone was investigated spectrphotometrically. The reaction followed a second-order rate law with first order with respect to each reactant. It was found that the reaction proceeded faster in dichloromethane than in acetonitrile and acetone. The formation of charge-transfer complex was observed at low temperatures. The results support a general mechanism with stepwise electron-proton-electron transfer through a charge-transfer complex. Intermediate N, N-dimethyl-p-toluidine was chosen as a model compound for insight into the reaction mechanism. From the pressure dependence of the rate, the activation volume was estimated to be - 34 cm3· mol-1. This largenegative activation volume indicates that a step with a large polarity increase is involved from the initial to the transition state. The discrepancy between the results of pressure effect and solvent effect was discussed.
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