Continuous sulphanilic acid prepn. by coking aniline hydrogen sulphate - uses N base-contg. feed in double-screw reactor of specified parameters to increase productivity

摘要

Prodn. comprises coking aniline hydrogen sulphate at 190-260 deg.C in a double screw reactor with parallel screws rotating in the same direction. The aniline hydrogen sulphate has added to it 0.1-10 wt.% of one or more organic bases with one or more sec. and/or tert. N atoms bonded to a (cyclo)alkyl gp. or bonded in a ring system. The starting mixt. is fed to an inlet zone or 120-150 deg.C, this zone having single-threaded tightly notched screw segments and being such that the starting mixt. is compressed in a ratio 1.2-3:1 by redn. of the chamber vol. in the forwarding direction. The compressed mixt. is then fed to a reaction zone which is at 200-260 deg.C and which consists of 3 sections and several chambers, the screws in this zone being multi-threaded and not tightly notched and the chamber vol. of the third section being larger than that of the last chamber in the inlet zone. The screws are turned at 4-10 rpm. USE/ADVANTAGE - The sulphanilic acid obtd. is of sufficient purity for direct use in dye synthesis or as a catalyst in phenyl-beta-naphthylamine prodn. It is obtd. at increased productivity and is of a quality only usually attained in solvent processes