Production of sulphonic acids of benzene, chlorobenzene, naphthalene and mono- and dialkyl benzenes

摘要

In the production of sulphonic acids of benzene, mono- and di-alkylbenzenes containing 1-4 carbon atoms in the alkyl group(s), chlorobenzene and naphthalene by treatment with sulphur trioxide, the formation of sulphone by-products is restrained by adding nitric acid or an oxygen-containing acid of phosphorus to the reaction mixture in a proportion of 0.1-5.0 parts per 100 parts of sulphur trioxide. The reaction may be effected in the presence or absence of a solvent, e.g. liquid sulphur dioxide or ethylene tetrachloride, and may be carried out at a temperature below zero down to -20 DEG C. The oxygen-containing acid of phosphorus may be an inorganic or organic compound, the use of orthophosphoric acid, metaphosphoric acid, polyphosphoric acid and phytic acid being exemplified. U.S.A. Specification 2,828,333 is referred to.