Chlorination of Methylcyclohexane in Molten Salt Media

Abstract The chlorination of methylcyclohexane in several molten metal chloride mixtures (ZnCl2/KCl/NaCl, CuCl/ KCl/NaCl, AlCl3/KCl/NaCl, and CuCl2/KCl/NaCl) has been carried out, using nitrogen gas as a diluent, at three levels of temperature (250, 350, and 450°C. The reactions in both ZnCl2 and CuCl melts were studied extensively, the former representing the molecular-type melt and the latter standing for the partially-ionic-type one. These reactions gave 1-, 2-, 3-, and 4-chloro-methylcyclohexanes and 1-, 3-, and 4-methylcyclohexenes as primary products, along with smaller amounts of toluene and methylcyclohexadiene. The formation of these olefins were interpreted by the subsequent elimination (by a carbonium-ion mechanism) of HCl catalytically enhanced by these melts from the methyl-chlorocyclohexane derivatives. The difference observed in the product distributions between ZnCl2 and CuCl melts was also explained by the studies of the effect of hydrogen chloride produced in these reactions over molten salts.