Kinetics and Mechanism of Anilinolyses of Ethyl Methyl, Ethyl Propyl and Diisopropyl Chlorothiophosphates in Acetonitrile
作者:Hasi Rani Barai、Md. Ehtesham Ul Hoque、Hai Whang Lee
DOI:10.5012/bkcs.2013.34.12.3811
日期:2013.12.20
methyl (2), ethyl propyl (4) and diisopropyl (7) chlorothiophosphates with substituted anilines and deuterated anilines are investigated kinetically in acetonitrile at . A concerted mechanism is proposed based on the selectivity parameters. The deuterium kineticisotope effects (DKIEs; ) are secondary inverse () with 2, primary normal and secondary inverse () with 4, and primary normal () with 7. The
Kinetics and Mechanism of Anilinolyses of Aryl Methyl and Aryl Propyl Chlorothiophosphates in Acetonitrile
作者:Hasi Rani Barai、Hai Whang Lee
DOI:10.5012/bkcs.2014.35.9.2797
日期:2014.9.20
Nucleophilic substitution reactions of Y-aryl methyl (8) and Y-aryl propyl (10) chlorothiophosphates with substituted anilines and deuterated anilines are investigated kinetically in acetonitrile at $55.0^\circ}C$. A concerted mechanism is proposed for 8 based on the negative $\rho}_XY}$ (= -0.23) value, while a stepwise mechanism with a rate-limiting leaving group departure from the intermediate is proposed for 10 based on the positive $\rho}_XY}$ (= +0.68) value. The deuterium kinetic isotope effects (DKIEs; $k_H/k_D$) are 0.89-1.28 and 0.62-1.20 with 8 and 10, respectively. Primary normal and secondary inverse DKIEs are rationalized by a frontside attack involving hydrogen bonded, four-center-type transition state and backside attack involving in-line-type transition state, respectively.
Kinetics and Mechanism of Pyridinolyses of Aryl Methyl and Aryl Propyl Chlorothiophosphates in Acetonitrile
作者:Hasi Rani Barai、Hai Whang Lee
DOI:10.5012/bkcs.2014.35.2.483
日期:2014.2.20
Constants ( k 2 × 10 3 /M –1 s –1 ) at 35.0 o C, NBO Charges at the Reaction Center P Atom,Summations of the Steric Constants and Selectivity Parameters ( X and XY ) for the Reactions of 1 - 11 with X-Pyridines in MeCNno R 1 OR 2 O k 2 × 10 3 a charge at P – ES X e XY 1 MeOMeO 1.54 c 1.687 0 1.09/0.20 –2MeOEtO 0.620 1.693 0.07 1.50/0.43 – 3 EtOEtO 1.19 c 1.701 0.14 1.02/0.29 –4EtO PrO 0.609
14/–1.02/–0.04 fa 35.0 o C 时 X = H 的值。 b Y = H 的值。 c 外推值。d 经验动力学数据。e 强/弱碱性吡啶。
Kinetics and Mechanism of Pyridinolyses of Ethyl Methyl and Ethyl Propyl Chlorothiophosphates in Acetonitrile
作者:Hasi Rani Barai、Hai Whang Lee
DOI:10.5012/bkcs.2013.34.11.3372
日期:2013.11.20
concave upwards with a break point at X = H (2) and 3-Ph (4), respectively. A stepwise mechanism with a ratelimiting leaving group expulsion from the intermediate is proposed based on the magnitudes of selectivity parameters for both substrates. The considerably large values of βX = 1.50(2) and 1.44(4) with strongly basic pyridines and relatively small values of βX = 0.43(2) and 0.36(4) with weakly
在 X = H (2) 和 3-Ph (4) 处分别有一个断点向上凹。基于两种底物的选择性参数的大小,提出了一种具有限速离去基团从中间体排出的逐步机制。βX = 1.50(2) 和 1.44(4) 的相当大的值与强碱性吡啶和相对较小的值 βX = 0.43(2) 和 0.36(4) 与弱碱性吡啶被解释为攻击方向的变化X-吡啶从正面到背面攻击氯化物离去基团。