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Electronic factors in the elimination kinetics of 2‐halosubstituted methanesulphonates in the gas phase
Author(s) -
Alvarez G. Jaime,
Chuchani Gabriel
Publication year - 1990
Publication title -
journal of physical organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.325
H-Index - 66
eISSN - 1099-1395
pISSN - 0894-3230
DOI - 10.1002/poc.610030707
Subject(s) - chemistry , arrhenius equation , propene , kinetics , torr , gas phase , toluene , atmospheric temperature range , reaction rate constant , medicinal chemistry , analytical chemistry (journal) , thermodynamics , activation energy , organic chemistry , catalysis , physics , quantum mechanics
The kinetics of the gas‐phase elimination of two 2‐haloethyl methanesulphonates were determined in a static system over the temperature range 310–380°C and pressure range 26–174 Torr. The reactions in seasoned vessels, with the free‐radical inhibitor propene and/or toluene always present, are homogeneous and unimolecular, and follow a first‐order rate law. The rate coefficients are given by the Arrhenius equations: for 2‐bromoethyl methanesulphonate log k 1 (s −1 ) = (11·70 ± 0·43)–(172·8 ± 4·8) kJ mol −1 (2·303 RT ) −1 and for 2‐chloroethyl methanesulphonate log k 1 (s −1 ) = (11·67 ± 0·50)–(173·9 ± 6·0) kJ mol −1 (2·303 RT ) −1 . The bromo compound was found to be more reactive than the chloro compound. At 340°C, for Br k 1 = 9·46 × 10 −4 s −1 and for Cl k 1 = 7·12 × 10 −4 s −1 . Apparently, electronic factors seem to be operating in these elimination reactions.