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Rate constants for the reactions of OH with CH 3 Cl, CH 2 Cl 2 , CHCl 3 , and CH 3 Br
Author(s) -
Hsu K.J.,
DeMore W. B.
Publication year - 1994
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/94gl00601
Subject(s) - reaction rate constant , chemistry , analytical chemistry (journal) , constant (computer programming) , physics , kinetics , organic chemistry , quantum mechanics , computer science , programming language
Rate constants for the reactions of OH with CH 3 Cl, CH 2 Cl 2 , CHCl 3 , and CH 3 Br have been measured by a relative rate technique in which the reaction rate of each compound was compared to that of HFC‐152a (CH 3 CHF 2 ) and (for CH 2 Cl 2 ) HFC‐161 (CH 3 CH 2 F). Using absolute rate constants for HFC‐152a and HFC‐161, which we have determined relative to those for CH 4 , CH 3 CCl 3 , and C 2 H 6 , temperature dependent rate constants of both compounds were derived. The derived rate constant for CH 3 Br is in good agreement with recent absolute measurements. However, for the chloromethanes all the rate constants are lower at atmospheric temperatures than previously reported, especially for CH 2 Cl 2 where the present rate constant is about a factor of 1.6 below the JPL 92‐20 value. The new rate constant appears to resolve a discrepancy between the observed atmospheric concentrations and those calculated from the previous rate constant and estimated release rates.