GB929052A - Process for the production of ú´-hydroxy-azo-naphthalenic compounds - Google Patents

Abstract

o-Hydroxy azo compounds are made by treating a diazotate, in solution or suspension, with a diazonium compound, at least one of the starting components being of the naphthalene series. It is stated that some of the products are new. Reaction is usually effected in a distinctly alkaline solution, e.g. pH 9-12, but may, with some diazotates, occur at pH's of 5-9. Stoichiometrical proportions of reactants are normally used. From a diazotate R-N=N-O(-), and a 1-diazonaphthalene compound, a 2-naphthol dye of formula <FORM:0929052/IV(a)/1> is obtained, a 2-diazonaphthalene compound yielding a 1-naphthol of formula <FORM:0929052/IV(a)/2> By-products may be obtained from the action of the alkali on the diazo compound, e.g. <FORM:0929052/IV(a)/3> and <FORM:0929052/IV(a)/4> The by-products may be isolated or redissolved and their production controlled by varying the proportions of diazotate and diazonium compound. From a diazonium compound <FORM:0929052/IV(a)/5> and a diazotate of the naphthalene series, similar dyes are obtained. With some of the 1-naphthol azo dyes thus obtained a second azo group may, by a secondary reaction, enter the molecule in a para position to the resulting hydroxy group. The second coupling may be counteracted by varying the proportions of diazotate and diazonium compound. The diazotates may be derived from carbo- and heterocyclic diazo compounds. Derivatives of benzene, naphthalene, anthracene and dehydrothiotoluidine disulphonic acid are mentioned. Substituents, e.g. sulphonic and carboxylic acid, benzenesulphonate, alkyl, nitro, acylamino, halogen and azo groups, may be present in the diazotates. Advantageously syn-diazotates are used. Specified diazotates include 4-sulphophenyl-syn-and anti and 4-nitro-, 2,5-dichloro-and 2-methoxy-4-nitro-phenyl-anti-diazotates. The diazotates need not be used in the isolated form. Thus the diazonium compounds, from which they are derived, may be converted, in situ, to diazotates by treatment with sodium carbonate or hydroxide. Illustrative of diazo compounds, to be so treated, are those derived from aniline, 4-benzoylamino-aniline, 4-aminoazobenzene-41-sulphonic acid, dehydrothiotoluidine-disulphonic acid, 6-nitro-2-naphthylamine-4,8-disulphonic acid and 1-aminoanthraquinone. Diazonium compounds specified include aniline, 4-nitroaniline, 2-naphthylamine-4-sulphonic and 3-carboxylic acids, 1-naphthylamine-3,6,8-trisulphonic acid, 1-aminoanthraquinone, 4-aminoazobenzene-41-sulphonic acid and 8-aminoquinoline-5-sulphonic acid. Numerous examples are provided of the preparation of the dyes, a variety of colours being obtained, and their use in dyeing wool.