Verfahren zur Herstellung von Azofarbstoffen

摘要

The invention comprises azo dyes free from sulphonic acid groups and having the general formula wherein A is a radical of an azo dye and R is a hydrocarbon radical having at least two carbon atoms and may be substituted and/or contain heteroatoms. Preferably, A is a radical D-N = N-E-, wherein D is a diazo component of the benzene series and E is a coupling component of the benzene, naphthalene or heterocyclic series. They are prepared by reacting an azo dye or a diazo or coupling component containing at least one primary amino group with an acid halide of the general formula wherein Hal is Cl or Br and R is as above, and when a diazo or coupling component is used subsequently forming the azo dye by diazotization and coupling. The acylation step is usually carried out at 0-200 DEG C. in presence of an organic solvent, many solvents are specified. Alternatively, an azo compound, a diazo or coupling component containing the group is reacted with a carboxylic acid ester of the general formula wherein R1 is a substituted or unsubstituted hydrocarbon radical and R2 and R3 are hydrogen or methyl or ethyl groups, preferably in a solvent or diluent at temperature up to 150 DEG C. and when a diazo or coupling component is used, forming the azo dye by diazotization and/or coupling. The reaction with the unsaturated ester is accelerated by inorganic bases and a polymerization inhibitor, e.g. hydroquinone may be present to prevent polymerization of the ester. The disperse dyes obtained dye synthetic materials, e.g. polyesters in yellow, orange and scarlet red shades.