Acid amide derivatives of azo compounds are manufactured by reacting a halide of a carboxylic acid containing at least one azo linkage separated from the carboxyl group by more than one carbon atom, and a hydroxy group in a position vicinal to the azo linkage, with a cyclic non-vattable amine, the starting materials being free from sulphonic acid and sulphonic acid amide groups (and preferably free from water-solubilizing groups generally). The reaction is preferably carried out in an anhydrous medium (e.g. in an inert organic solvent, such as toluene, mono-, di- or tri-chlorobenzenes or nitrobenzene, at a raised temperature) and in the presence of an acid-binding agent (e.g. anhydrous sodium acetate, pyridine or anhydrous ammonia), and, if desired, without isolating the acid halide from the reaction mixture in which it is prepared from the corresponding acid, e.g. by the action of thionyl chloride or phosphorus pentachloride or pentabromide. Advantageously a halide of a monocarboxylic acid is reacted with an amine containing more than one amino group (especially a diamine), or a dicarboxylic acid dihalide with a monoamine, whereby there are obtainable dyestuffs of the following preferred types (in each of which X represents a hydrogen atom or an alkyl group, and all of which are free from sulphonic acid and sulphonic acid amide groups):- <FORM:0730384/IV (c)/1> (wherein R1 and R2 each represent the residue of a diazo component, R3 and R4 each represent a fused-on residue, and <FORM:0730384/IV (c)/2> represents the residue of a cyclic non-vattable diamine); <FORM:0730384/IV (c)/3> (wherein R1, R2 and <FORM:0730384/IV (c)/4> are as before, and R3-CO- and R4-CO- each represent the residue of a coupling component in which the -CO- group is separated from the azo linkage by more than one carbon atom and which contains, in a position vicinal to the azo linkage, a hydroxy group which in at least one case is an enolized keto group); <FORM:0730384/IV (c)/5> (wherein R1, R2 and <FORM:0730384/IV (c)/6> are as before, and R3 and R4 each represent the residue of a coupling component having a hydroxy group in a position vicinal to the azo linkage); and <FORM:0730384/IV (c)/7> (wherein -OC-R1-CO- represents the residue of a dicarboxylic acid HOOC-R1-COOH containing an azo linkage separated from each of the carbonyl groups by more than one carbon atom and containing a hydroxy group in a position vicinal to the azo linkage, and <FORM:0730384/IV (c)/8> each represent the residue of a cyclic non-vattable monoamine). The products are useful in pigment printing processes in which the pigments are affixed to the substratum (e.g. textile fibres, paper, or fabrics made of glass fibres) by means of adhesives (e.g. casein, hardenable plastics, or polyvinyl chloride or acetate solutions or emulsions), in the manufacture of lakes, and in the coloration of solutions and products made of acetylcellulose, nitrocellulose, natural or artificial resins or rubber. Those which contain a hydroxy group other than an enolized keto group may be converted into printing preparations by esterification with components imparting solubility, e.g. benzoic acid-m-sulphochloride. Examples (1) to (7) and (9) to (16) describe the interaction of various combinations of the following reactants in the proportion of two mols. of the acid halide to one of the diamine: the monocarboxylic acid halides from the monoazo dyestuffs 5 - nitro - 2 - amino - 1 - methoxybenzene, 1 - amino - 2 - methyl - 4 - chlorobenzene, 1 - amino-2 : 5-diethoxy- or -dimethoxy-4-benzoylaminobenzene, 1 - amino - 2 - methoxy - 4 - benzoylamino - 5 - methylbenzene, o - chloraniline or 1-amino-2 : 5-dimethoxy-4-chlorobenzene --> 2 : 3 - hydroxynaphthoic acid, 1 - amino - 2 - methyl-5-chlorobenzene --> 2-hydroxyanthracene - 3 - carboxylic acid, p - aminobenzoic acid --> b -naphthol, o-chloraniline or 1-amino-2 - methyl - 5 - chlorobenzene --> 1 - phenyl - 3 - methyl - 5 - pyrazolone - 41 - carboxylic acid, p - aminobenzoic acid --> 1 - (41 - methylphenyl) - 3 - methyl - 5 - pyrazolone, 2 - nitro - 4-methylaniline --> 4-acetoacetylaminobenzoic acid, p-aminobenzoic acid --> 4-chloro-2 : 5-dimethoxy - 1 - acetoacetylaminobenzene, and 2-nitro-4-methylaniline --> 2-chloro-5-acetoacetylaminobenzoic acid; o-tolidine, benzidine, 1 : 5-diaminonaphthalene, 4 : 41-diamino-3 : 31-dichlorodiphenylmethane, 4 : 41 - diaminodiphenyl sulphone and 3 : 31-dichloro-4 : 41-diaminodiphenyl. In further examples: (8) benzidine is reacted with an equimolecular proportion of each of the acid chlorides from the dyestuffs 1 - amino - 2 - methyl - 3 - chlorobenzene --> 2 : 3-hydroxynaphthoic acid and 1 - amino - 2 : 5 - diethoxy - 4 - benzoylaminobenzene --> 2 : 3-hydroxynaphthoic acid; (17) 3-aminopyrene is reacted with the acid chloride of the dyestuff 1-amino-2-methyl-4-chlorobenzene --> 2 : 3-hydroxynaphthoic acid; (18) 2 mols. of 2-aminochrysene are reacted with 1 mol. of the dichloride of the dyestuff p-aminobenzoic acid --> 2 : 3-hydroxynaphthoic acid. Lists are given of additional starting materials, including diamines of the diphenyl ether, benzophenone, benzoylaniline, diphenylurea, stilbene, dibenzyl, diphenylamine, azobenzene, chrysene and benzthiazole series, or containing two benzene rings linked by the group -HN-CO-C2H4-CO-, and diazo components containing trifluoromethyl or sulphone groups.ALSO:Acid amide derivatives of azo dyestuffs, obtained by reacting a halide of a carboxylic acid containing at least one azo linkage separated from the carboxyl group by more than one carbon atom, and a hydroxy group in a position vicinal to the azo linkage, with a cyclic non-vattable amine, may be used for colouring artificial masses, e.g. by incorporating them in a finely-dispersed form in a spinning solution for the production of artificial silk of viscose, cellulose esters or ethers, superpolyamides or superpolyurethanes, or by incorporating them in synthetic resin masses for the production of foils. In an example, the product obtained by condensing 1 mol. of o-tolidine with 2 mols. of the acid chloride of the monoazo-dyestuff 2 : 5 - dimethoxy - 4 - chloraniline --> 2 : 3 - hydroxynaphthoic acid, is rolled with polyvinyl chloride and dioctyl phthalate to produce a violet-coloured foil.