Preparation of stable solutions of azo dyes of m-phenylenediamine by reaction with formic acid
AssigneeBASF SE
InventorKarl Schmeidl
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Abstract
Stable solutions of azo dyes obtained by diazotizing and coupling m-phenylenediamine or derivatives thereof are prepared after the reaction has ended by treating the resulting reaction mixture with from 0.1 to 1.2 moles of formic acid, based on 1 mole of m-phenylenediamine, at from 60.degree. C. to the boiling point of the reaction mixture.
Claims2
A process for preparing a stable solution of an azo dye obtained by diazotizing and coupling unsubstituted or C.sub.1 -C.sub.4 -alkyl- or C.sub.1 -C.sub.4 -alkoxy-substituted m-phenylenediamine in acetic acid, which comprises, after the reaction has ended, treating the resulting reaction mixture with from 0.1 to 1.2 moles of formic acid, based on 1 mole of m-phenylenediamine, at from 60.degree. C. to the boiling point of the reaction mixture.
Dependencies are inferred from the claim text.