Eliminations from (E)-O-arylbenzaldehyde oximes promoted by hydroxide in 60% aq. Dimethyl sulphoxide. Mechanism and transition-state characteristics of nitrile-forming eliminations
作者:Bong Rae Cho、Jong Chan Lee、Nam Soon Cho、Kee Dong Kim
DOI:10.1039/p29890000489
日期:——
Reactions of the (E)-O-arylbenzaldehyde oximes (1; Ar = 2,4-dinitrophenyl), (2; Ar =p-nitrophenyl), and (3; Ar = phenyl) with OH– in 60% aq. DMSO have been investigated. The eliminations are quantitative, producing only benzonitriles and aryloxides. The observation of second-order kinetics, k2OD–/k2OH–= 1.15–1.84, and βlg=–0.59 is consistent with an E2 mechanism. The Hammett ρ and k2OD–/k2OH– values
(的反应ë) - Ö -arylbenzaldehyde肟(1 ; Ar为2,4-二硝基苯基),(2 ; Ar为p硝基苯基),和(3 ; Ar为苯基)与OH -在60%的水溶液。已对DMSO进行了调查。消除是定量的,仅产生苄腈和芳基氧化物。的二级动力学的观察,ķ 2 OD - / ķ 2 OH - = 1.15-1.84,和β LG = -0.59是具有一致的ë 2机构。哈米特ρ和k 2 OD – / k 2OH –离开群体较弱的人会增加价值。对于给定的衬底上的ķ 2 OD - /ķ 2 OH -值保持(实验误差之内)大致恒定,尽管在β芳基取代基的变化。过渡态参数的这些变化可以根据所涉及的形成亚硝酸盐的不同过渡态来解释。