Premium
Push‐Pull Electronic Activation of Reactions
Author(s) -
Robinson R.
Publication year - 1972
Publication title -
israel journal of chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.908
H-Index - 54
eISSN - 1869-5868
pISSN - 0021-2148
DOI - 10.1002/ijch.197200037
Subject(s) - chemistry , carbonium ion , anisole , ion , ring (chemistry) , computational chemistry , displacement (psychology) , atom (system on chip) , electron , conjugated system , stereochemistry , organic chemistry , quantum mechanics , catalysis , psychology , physics , polymer , computer science , psychotherapist , embedded system
Electron delocation, simple or conjugated, is postulated in many reaction mechanisms which are assumed to proceed by way of an activated phase. One‐way processes involving electron displacement are acceptable for additions, but dubious for substitutions. In the text below the bromination of anisole is mentioned. If it is assumed that the Br atom combines with C p ‐ to OMe as the result of a full electron displacement, then it becomes necessary to reverse such displacements to remove H from the p ‐position. The present hypothesis is that instead of two major translocations the same result could be achieved by a kind of oscillating displacement of smaller amplitude, alternating in opposite directions. In this case, the aromatic structure is never disturbed to any serious extent and side‐reactions are accordingly minimal. The theory is further exemplified by the reactions of acetals and similar types, including the ring‐forms of the sugars. Mention is also made of the probability that reactions of carbonium ions can be interpreted in terms of partial valencies.