Continuous process for aminoazobenzene

Claim 1

A continuous process for the preparation of a carbocyclic aromatic aminoazo compound comprising the steps of (1) intimately mixing a reactant stream containing a large excess of a carbocyclic aromatic primary amine, unsubstituted in the position para to the amino group, a mineral acid and water, with a reactant stream containing an aqueous solution of an alkali metal nitrite, each of said reactant streams having been separately heated to a temperature in the range of 10° C. to 40° C. and the combined mixed streams containing a mole ratio of primary amine to mineral acid to alkali metal nitrite in the range of 3.5-20:1.2-9:1, (2) immediately passing said premixed reactant streams directly to a tubular reactor, at a rate such as to provide a residence time in said reactor of from about 1 to 10 minutes, wherein said reactant streams react to form said aminoazo compound at a temperature in the range of 40° C., said temperature resulting solely from the heat of reaction, (3) neutralizing the reaction product stream, containing said aminoazo compound as the acid salt, with an aqueous alkali metal hydroxide, (4) separating the resulting organic phase from the aqueous phase, and (5) recovering said aromatic aminoazo compound from the organic phase.