MECHANISM OF DEBROMINATION OF 1-ARYL-1,2-DIBROMO-2-NITROPROPANES PROMOTED BY SECONDARY-AMINES IN ACETONITRILE

被引：23

作者：

CHO, BR

LEE, SJ

KIM, YK

机构：

[1] Department of Chemistry, Korea University, 1-Anamdong

来源：

JOURNAL OF ORGANIC CHEMISTRY | 1995年 / 60卷 / 07期

关键词：

D O I：

10.1021/jo00112a030

中图分类号：

O62 [有机化学];

学科分类号：

070303 ; 081704 ;

摘要：

Debromination reactions of erythro-dl-1-aryl-1,2-dibromo-2-nitropropanes with secondary amines in MeCN have been investigated kinetically. Reactions of erythro-dl-1-aryl-1,2-dibromo-2-nitropropanes with secondary amines in MeCN are stereospecific, producing (E)-1-aryl-2-nitropropenes quantitatively. The rate equation for the reaction is k(obs) = k(2)[R(2)NH] + k(3)[R(2)NH](2), indicating that the reactions proceed by both uncatalyzed and base-catalyzed pathways. The Hammett rho, Bronsted beta, Delta H-double dagger, and Delta S-double dagger values for the k(2) and k(3) processes are 1.22 +/- 0.04 and 1.20 +/- 0.02, 0.77 +/- 0.05 and 1.05 +/- 0.13, 5.6 +/- 0.3 and 1.7 +/- 0.1 kcal/mol, and -49.1 +/- 4.5 and -60.7 +/- 204 eu, respectively. For dehalogenation reactions from vicinal dibromo and bromochloro compounds, the element effect of the leaving group k(Br)/k(Cl) = 7.8 and 25 have been determined for the k(2) and k(3) processes. From these results, the mechanism and the transition-state character of these reactions are assessed.

引用

页码：2072 / 2076

页数：5

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