Patent GB-278100-A (GB)
Title: Improved process for the manufacture of dinaphthyldicarboxylic acids
IPC: C07C63/72
Filed: 1926-07-06
Abstract: 278,100. Carpmael, W., (I. G. Farbenindustrie Akt.-Ges.). July 6, 1926. Dinaphthyl-dicarboxylic acids and their substitution products are obtained by treating diazo compounds derived from o- or periamino -naphthoic acids or their derivatives with suitable reducing agents. e.g. an ammoniacal solution of cuprous oxide or a neutral solution of sodium sulphite or a ferrous salt. In examples (1) 1 : 1<1>- dinaphthyl-8 : 8<1>-dicarboxylic acid is obtained by reducing diazotized 1: 8-aminonaphthoic acid with an ammoniacal solution of cuprous oxide, made by passing sulphur dioxide through an ammoniacal solution of copper sulphate, or with a cuprous chloride solution obtained by reducing a solution of copper sulphate and common salt with sodium bisulphite; the diethyl ester may be obtained by esterifying with ethyl alcohol in the usual manner, (2) 2 2<1>-dinaphthyl-3 : 3<1>-dicarboxylic acid is similarly obtained from 2 : 3-aminonaphthoic acid; it dissolves in concentrated sulphuric acid with a red colour, probably due to the formation of dibenzofluorenone-3-carboxylic acid, (3) 1 : 1<1>-dinaphthyl-2 : 2'-dicarboxylic acid is similarly obtained from 1 : 2-aminonaphthoic acid, (4) 2 : 3-aminonaphthoic ethyl ester is diazotized and reduced with an ammoniacal solution of copper sulphate and ferrous sulphate; the product is 2 : 2<1>-dinaphthyl-3 : 3<1>-dicarboxylic diethyl ester, which yields the acid when saponified in the usual manner, (5) 1-chlor-2-aminonaphthalene-3- carboxylic acid, obtained by the action of oxidizing agents on 1-chlor-2 : 3-naphthisatin, is diazotized and reduced with ammoniacal cuprous oxide solution, or with a reducing solution obtained by mixing solutions of copper sulphate, ammonia, hydroxylamine hydrochloride and caustic potash ; the product is 1 : 1<1>-dichlor-2 : 2'- dinaphthyl-3 : 3<1>-dicarboxylic acid (6) 4-bromnaphthostyril is saponified to 1-amino-4-bromnaphthalene-8-carboxylic acid, the product is diazotized and reduced with ammoniacal cuprous oxide solution ; 4 : 4<1>-dibrom-1 : 1<1>-dinaplithyl- 8 : 8<1>-dicarboxylic acid is obtained, (7) 4-chlornaphthostyril. which may be obtained by chlorinating naphthostyril, is saponified to 1-amino-4- chlornaphthalene-8-carboxylic acid, diazotized and reduced with ammoniacal cuprous oxide solution, 4 : 4<1>-dichlor-1 : 1<1>-dinaphthyl-8 : 8<1>-dicarboxylic acid being obtained and may be converted into its diethyl ester; 5-chlornaphthostyril (obtained by converting 8-amino-5-chlornaphthalene-1-sulphonic acid into the 8-cyano derivative by Sandmeyer's reaction, and melting the product with caustic alkali as described in Specification 276,126) similarly yields 5: 5<1>-dichlor-1 : 1<1>-dinaphthyl-8 : 8<1>-dicarboxylic acid, (8) naphthostyril-4-sulphonic acid, obtained by sulphonating naphthostyril, yields, on saponification, 1-amino-4- sulphonaphthalene-8-carboxylic acid, from which 1 : 1<1>-dinaphthyl-4 : 4<1>-disulpho-8 : 81-dicarboxylic acid is obtained; and (9) 5-methoxy-1: 8-aminonaphthoic acid, obtained by the process described in Specification 276,126, yields 5 : 5-dimethoxy- 1:1<1>-dinaphthyl-8:8<1>-dicarboxylic acid; the corresponding diethoxy compound can be similarly obtained. Specification 21915/12 also is referred to.