Zeolite-assisted nitration of neat toluene and chlorobenzene with a nitrogen dioxide/molecular oxygen system. Remarkable enhancement of para-selectivity

In the presence of molecular oxygen and HZSM-5, neat toluene reacted with liquid nitrogen dioxide in a regioselective manner at room temperature to yield mononitrotoluenes as the main product, where the para isomer predominated up to 90% and the ortho–para isomer ratio improved to 0.08. Chlorobenzene behaved similarly, giving a para-predominant nitration product.