PROCESS FOR PREPARING SODIUM-M-NITROBENZENESULFONATE

摘要

Nitrobenzene is combined with at least one mole of SO3, as 65% oleum, resulting in an exothermic reaction. The reactants are combined slowly, and/or cooling is supplied, so as to keep the reaction temperature in the range between about 80 DEG and 130 DEG C. The resulting sulfonation mass is held at a temperature between about 80 and 130 DEG C for a sufficiently long period of time to effect substantial completion of the sulfonation reaction. The sulfonation mass is then added to sufficient caustic soda to convert the acids therein to Na2SO4 and sodium m-nitrobenzenesulfonate. At a pH between 7 and 8.6 and at a temperature between 80 DEG and 100 DEG C, sufficient water is provided by, or added to, the resulting mass so that the sodium m-nitrobenzenesulfonate is dissolved therein and at least 60% of the Na2SO4 is precipitated, making it possible to separate the one from the other.