Para selective chlorination of toluene with an L-zeolite catalyst Original Research Article

The liquid phase chlorination of toluene with gaseous chlorine using various zeolites as catalysts has been studied. Zeolite K-L is found to be more selective than the other zeolites and the conventional catalyst, FeCl3. The reaction over SiO2 shows lower para-selectivity compared to the zeolites. The influence of various parameters such as the type of zeolite, nature of the solvent, reaction temperature, catalyst concentration, ClCH2COOH/ catalyst ratio and chlorine gas flow rate on the para/ortho-isomer ratio in the chlorination of toluene are reported. The yield of para-chlorotoluene is significantly enhanced by increasing the reaction temperature (studied up to 383 K) and the catalyst amount. The highest para/ ortho ratio (6.66) was obtained over zeolite K-L when a mixture of 1,2-dichloroethane/ toluene in a molar ratio of 1.7 was used. The HCl formed during the reaction deactivates K-L. The selectivity (para/ ortho) decreases marginally with increasing conversion in zeolite K-L catalyzed chlorination.