par Mulders, Julien 
;Nasielski, Jacques
Référence Bulletin des Sociétés chimiques belges, 72, 5-6, page (322-345)
Publication Publié, 1963
;Nasielski, Jacques Référence Bulletin des Sociétés chimiques belges, 72, 5-6, page (322-345)
Publication Publié, 1963
Article révisé par les pairs
| Résumé : | The iodide ion induced elimination of bromine in vic. dibromides in acetone has been followed for some substituted ethanes (k20°; E; log PZ): 1,2‐dibromopropane (6,31. 21,7; 11,0), 2,3‐dibromobutanes (meso: 5,50. 10–6; 17,5; 7,8) (dl: 1,74. 18,3; 7,9), 1,2‐dibromo‐2‐méthylpropane (1,70. 10–6; 22,6; 11,1), 2,3‐dibromo‐2‐methylbutane (1,38. 19,1; 9,4) 2,3‐dibromo‐2,3‐dimethylbutane (6,03. 10–4; 17,3; 9,7), 1,2‐dibromo‐1,2‐diphenylethane méso (1,15. 10–3; 16,0; 9,0). The influence of ionic strength and of added bromide ion allows to distinguish two different mechanisms for the direct elimination. A) for the first members of the series, there is evidence for the existence of an intermediate, whose structure is suggested to be of type A. B) for more substituted ethanes, the results agree nicely with a synchronous transition state B; the rate is a function of the stabilisation of the incipient double bond. Copyright © 1963 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim |
