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Catalysis by HBr in the bromination of o ‐xylene in acetic acid
Author(s) -
Yesodharan E. P.,
Rajaram J.,
Kuriacose J. C.
Publication year - 1976
Publication title -
international journal of chemical kinetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.341
H-Index - 68
eISSN - 1097-4601
pISSN - 0538-8066
DOI - 10.1002/kin.550080209
Subject(s) - halogenation , chemistry , mesitylene , bromine , hydrogen bromide , acetic acid , catalysis , bromide , electrophile , medicinal chemistry , halogen , organic chemistry , alkyl
Hydrogen bromide is known to inhibit the bromination of aromatic substrates (ArH), either by fixing up bromine as HBr 3 or ArH as ArH · HBr. However, there is catalysis by HBr in the bromination of mesitylene in acetic acid. The bromination of o ‐xylene in acetic acid in the dark is found to be autocatalytic, and the reaction is overall third order, first order in o ‐xylene with the orders in Br 2 and HBr depending on the concentrations. A composite rate expression involving Br 2 and HBr as electrophiles has been proposed and verified using iodine bromide as a catalyst where the orders are one in each of the reactants, irrespective of the concentrations used.