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Molecular rearrangements in homogeneous gas‐phase elimination reactions. Pyrolysis kinetics of alkyl methanesulphonates
Author(s) -
Chuchani Gabriel,
Martin Ignacio,
Dominguez Rosa M.,
Rotinov Alexandra,
Pekerarm Sara,
Gomez Matilde
Publication year - 1993
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.610060204
Subject(s) - chemistry , homogeneous , methane , intramolecular force , alkyl , kinetics , reaction rate constant , medicinal chemistry , gas phase , torr , atmospheric temperature range , molecule , stereochemistry , organic chemistry , thermodynamics , physics , quantum mechanics
The rates of elimination of several alkyl methanesulphonates were determined in a seasoned, static reaction vessel over the temperature range 300–420°C and the pressure range 28–163 Torr. The reactions are homogeneous, unimolecular and follow a first‐order rate law. The overall rate coefficients are given by the following equations: for isobutyl methanesulphonate, log k 1 (s −1 ) = (12·51 ± 0·38) − (177·0 ± 2·1) kJ mol −1 (2·303 RT ) −1 ; for 2‐phenyl‐1‐propyl methanesulphonate, log k 1 (s −1 ) = (12·62 ± 0·04) − (176·2 ± 0·5) kJ mol −1 (2·303 RT ) −1 ; for neopentyl methane‐sulphonate, log k 1 (s −1 ) = (13·35 ± 0·42) − (198·2 ± 5·2) kJ mol −1 (2·303 RT ) −1 ; and for 3‐chloro‐2,2‐dimethyl‐1‐propyl methanesulphonate, log k 1 (s −1 ) = (13·87 ± 0·42) − (218·2 ± 5·4) kJ mol −1 (2·303 RT ) −1 . Rearrangements in these methanesulphonate pyrolyses may proceed via an intimate ion‐pair type of mechanism. Consequently, the results appear to confirm that intramolecular migration through autosolvation is possible in gas‐phase elimination reactions of certain types of organic molecules.