Utilising solvent laden hydrogen chloride gas streams - by direct reaction with sulphur tri:oxide to give chlorosulphonic acid for use e.g. in chlorosulphonation reactions

摘要

Process for utilising solvent-laden HCl gas comprises reacting a mixt. of the HCl and SO3, using stoichiometric amts. of HCl and SO3 or a slight excess of HCl over SO3, at -20 to +60 degrees, esp. 0-40 degrees C, in a chlorosulphonic acid medium to form chlorosulphonic acid. In an example, HCl gas laden with 1,2-dichloroethane (I), resulting from the sulphonation of naphthalene with ClSO3H, was passed continuously to a jet reactor tube with liq. or gaseous SO3 at 15-20 degrees C using >=1% excess HCl. Cl2O3H contg. 1-2% (I) was obtd. in a yield of >99% on HCl input. Process is esp. useful for utilising solvent-laden HCl gas evolved e.g. during the sulphochlorination of aromatic hydrocarbons e.g. naphthalene, anthracene or benzene using chlorosulphonic acid in an inert solvent medium. Process obviates the need to purify the HCl stream and the resulting prod. can be recycled directly to the chlorosulphonation reaction, utilising the HCl evolved and overcoming effluent problems. The HCl conversion is carried out at relatively low temps., so that the solvent is not attacked by the SO3.