The phenomenon of catalytic maximum has been investigated in the bromination of p-bromophenol (ArH) using iodine and anhydrous aluminium chloride as catalysts. The effective catalysts have been shown to be iodine bromide in acetic acid and carbon tetrachloride media, and AlCl3, Br2 in acetic acid. A correlation between the ratio of the reactants at the catalytic maximum, and the order in the effective catalyst has been deduced and experimentally verified. © 1969, CSIRO. All rights reserved.

Jayaraman Rajaram

Joseph C. Kuriacose

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IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

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IIT Madras

Bromination of p-bromophenol. II. Catalysis by iodine and anhydrous aluminium chloride

Australian Journal of Chemistry

Hydrogen bromide is known to inhibit the bromination of aromatic substrates (ArH), either by fixing up bromine as HBr3 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 Br2 and HBr depending on the concentrations. A composite rate expression involving Br2 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. Copyright © 1976 John Wiley &amp; Sons, Inc.

International Journal of Chemical Kinetics

Catalysis by HBr in the bromination of o‐xylene in acetic acid

The role of pyridine (Py) in the bromination of p‐bromophenol (ArH) in CCl4 has been investigated. At constant concentrations of ArH and Br2, the rate of disappearance of Br2 increases to reach a limiting value as the concentration of Py is increased. The mechanism suggested to account for the rate expression, Rate = constant [ArH] [Br2]T[Py]T, obtained from the initial rate studies, involves the interaction between ArH and the brominating species Py. Br2, in the rate determining step. Py acts as a catalyst probably by virtue of its ability to polarise the Br‐Br bond. Copyright © 1971 WILEY‐VCH Verlag GmbH &amp; Co. KGaA, Weinheim

Israel Journal of Chemistry

Bromination of p‐Bromophenol in the Presence of Pyridine

The kinetics of bromination of a reactive substrate like anisole and a less reactive substrate like p-nitrophenol has been investigated in acetic acid medium with iodine added to accelerate the reaction. The effective catalyst has been shown to be iodine bromide. The experimental results obtained from a study of the phenomenon of catalytic maximum in these reactions are in good agreement with the theoretical expectations. © 1970 Indian Academy of Sciences.

Journal	Australian Journal of Chemistry
ISSN	00049425
Open Access	No