To desalt an aqueous suspension comprising the subject diazonium compound and an electrolyte containing Na ions in relation to the use for the production of an azo dye, etc., by passing the specific aqueous suspension through a semipermeable membrane.
An aqueous suspension comprising (A) an electrolyte containing sodium ions and (B) an organic diazonium compound, e.g. a compound represented by the formula (Y- is an anion, especially a halide, a sulfate or the like) or a betaine thereof is passed through a semipermeable membrane and thereby desalted. The above semipermeable membrane is a precise filtration membrane or an ultrafiltration membrane and the membrane process is preferably carried out by a means of the so-called cross-flow filtration. The desalting of the suspension is preferably conducted at a value of pH 0.5-5 and 5-70°C temperature. The resultant desalted organic diazonium compound is preferably coupled with a coupling compound to thereby produce an azo compound.
JOHNSON ANDREW D
MURPHREE SAMUEL SHAUN
THOLEMA EDZARD DR
HOFFMANN HELMUT
ZARGES WOLFGANG DR
FRANK WOLFGANG DR
BURKHARDT BETTINA
