Meta nitrobenzene sulphonic acid by sulphon - ation of nitrobenzene

摘要

The reaction is carried out with a SO3-containing contact-gas in the presence of catalysts in 2 reaction steps. It the 1st step, the contact gas is introduced in nitrobenzene at 30-50 degrees C and, in the 2nd step, the products are decomposed at 80-150 degrees C. Preferably, the catalyst is (NH4)2SO4, CH3COOH, or pyridine or a mixture of any 2 or 3 of these cmpds. Pref. either both steps are continuous or both steps are discontinuous. Advantages: higher yields; the formation of sulphones and gypsum is reduced; the difficulties and high costs entailed when oleum or liq. SO3 are used are avoided.