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The Mechanism Study of Free Radical S H 2′ Reactions by Leaving Group Effect and Secondary α‐Deuterium Kinetic Isotope Effect
Author(s) -
Wu YuhWern,
Huang ShuHui,
Tseng TeongFuh,
Yang JyhFerng
Publication year - 2004
Publication title -
journal of the chinese chemical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.329
H-Index - 45
eISSN - 2192-6549
pISSN - 0009-4536
DOI - 10.1002/jccs.200400150
Subject(s) - chemistry , kinetic isotope effect , deuterium , leaving group , allylic rearrangement , chloride , photochemistry , elimination reaction , kinetic energy , catalysis , medicinal chemistry , organic chemistry , physics , quantum mechanics
The reactions of free radical addition to allylic compounds are believed to proceed the S H 2′ mechanism. It is not clear whether the S H 2′ mechanism is concerted or stepwise. The leaving group effects and the secondary α‐deuterium kinetic isotope effects in free radical S H 2′ reactions have been determined. The leaving group effect, k Br /k Cl , is from 1.88 to 14.3. The secondary α‐deuterium kinetic isotope effects, k H /k D , are 1.20 for 2‐methylallyl chloride and 1,1‐d 2 ‐2‐methylallyl chloride and 1.22 for allyl chloride and 1,1‐d 2 ‐allyl chloride. The free radical S H 2′ reactions seem to favor the concerted mechanism.