Advances in the Development of Methane Bromination

Abstract

The bromination reactions of Methane were studied and majority of the work done so far was outlined, as these reactions have gained immense importance for years in the industrial sector. Thermodynamically, Bromine (Br) is the most suitable species for halogenation of methane. Bromination of methane proceeds via a radical chain mechanism which involves radical intermediates. The mechanism consists of three key steps i.e. Initiation, propagation and termination. It results in the formation of methyl bromide and hydrogen bromide. Hydrogen bromide has been found to inhibit the bromination of methane. However, it has no influence on the bromination of methyl bromide. Bromination of methane can occur both thermally as well as photochemically, following the same free radical chain mechanism. It is a gently exothermic reaction. Studies of the transition state showed that the symmetry for such reaction is of C₃v type. Monobromination reaction is hard to control. Supported Lewis acid halides-oxyhalides were found to be suitable as catalysts for monobromination of methane. Catalytic bromination gave more than 90 %.conversions with selectivity in methyl bromide. Oxidative bromination of methane occurs when FePO₄/SiO₂ or BaO/SiO₂ are used as catalyst.