Concentrated, aqueous solutions of salts of acetoacetylamino-arylsulphonic acids and method of forming concentrated solutions of azo dyestuffs therefrom

Process for the preparation of a concentrated dyestuff solution substantially free from foreign ions comprising

• (a) reacting a compound of the formula
• H.sub.2 N--R--(SO.sub.3 H).sub.m
• wherein
• R is benzene or naphthalene unsubstituted or substituted with fluorine, chlorine, bromine, C.sub.1 -C.sub.4 -alkyl, C.sub.1 -C.sub.4 -alkoxy, C.sub.1 -C.sub.4 -alkylcarbonylamino, C.sub.1 -C.sub.4 -alkylsulphonylamino, phenylazo, naphthylazo, or phenylazo or naphthlazo substituted by methyl, methoxy, chloride, or nitro or is benzene substituted with carboxylcarbonylamino;
• and
• m is 1, 2 or 3;
• with diketene in an aqueous or aqueous-organic solvent while maintaining a reaction pH>3 by adding an amine of the formula ##STR16## wherein R.sub.1 is hydroxyalkyl, alkoxyalkyl or --(C.sub.2 H.sub.4 O).sub.n --R.sub.4 ;
• R.sub.2 and R.sub.3 are alkyl, hydroxyalkyl, alkoxyalkyl or --(C.sub.2 H.sub.4 O).sub.n --R.sub.4,
• or, together with the N atom, are pyrrolidine, morpholine, or piperazine;
• or by adding an ammonium hydroxide containing a cation of the formula ##STR17## wherein R.sub.1, R.sub.2 and R.sub.3 are as defined above and R.sub.5 is R.sub.2 or R.sub.3, to form a concentrated salt solution substantially free from foreign ions of the coupling component of the formula
• .sub.m (Me.sup..sym..crclbar. O.sub.3 S)--R--NHCO--CH.sub.2 --CO--CH.sub.3
• wherein Me is ##STR18## (b) reacting the resultant concentrated salt solution with a diazotized amine of the formula
• A--NH.sub.2
• wherein A is the radical of a diazo component to form a concentrated solution of the corresponding azo dyestuff.