Kinetics and Mechanism of the Anilinolysis of Dibutyl Chlorothiophosphate in Acetonitrile
作者:Md. Ehtesham Ul Hoque、Hai-Whang Lee
DOI:10.5012/bkcs.2012.33.3.843
日期:2012.3.20
The nucleophilic substitution reactions of dibutyl chlorothiophosphate (4S) with substituted anilines ($XC_6H_4NH_2$) and deuterated anilines ($XC_6H_4ND_2$) are investigated kinetically in acetonitrile at $55.0^\circ}C$. The obtained deuterium kinetic isotope effects (DKIEs;$k_H/k_D$) are primary normal ($k_H/k_D$ = 1.10-1.35). A concerted mechanism involving predominant frontside nucleophilic attack is proposed on the basis of the primary normal DKIEs and selectivity parameters. Hydrogen bonded, four-center-type transition state is proposed. The steric effects of the two ligands on the anilinolysis rates of the chlorothiophosphates are discussed. The anilinolyses of P=S systems are compared with those of their P=O counterparts on the basis of the reactivities, thio effects, selectivity parameters, and DKIEs.
丁基氯硫酯(4S)与取代苯胺($XC_6H_4NH_2$)和重氘取代苯胺($XC_6H_4ND_2$)的亲核取代反应在<越南>$55.0^\circ}C$越南>的乙腈中进行了动力学研究。获得的氘动力学同位素效应(DKIEs;$k_H/k_D$)为一级正常型($k_H/k_D$ = 1.10-1.35)。根据一级正常DKIEs和选择性参数,提出了一种以前侧亲核攻击为主的协同机制。提出了氢键结合的四中心型过渡态。讨论了两种配体对氯硫磷酸酯苯胺水解速率的立体效应。在反应性、硫效应、选择性参数和DKIEs的基础上,比较了P=S系统的苯胺水解与其P=O对应物的苯胺水解。