Patent GB-539471-A (GB)
Title: Improvements in or relating to napthalene derivatives and method of obtaining same
Filed: 1940-03-27
Abstract: 539,471. Methyl-4 amino-1-naphthols. JACKSON, L. MELLERSH-. (Parke, Davis & Co.). March 27,1940, No. 5549. [Class 2 (iii)] A methyl-4-amino-1-naphthol having a methyl group in the 2 or 3 position is made:-(1) By converting a 1 : 4-naphthoquinone having a methyl group in the 2 or 3 position into a monoxime and then reducing. (2) By reducing a 1-nitronaphthalene having a methyl group in the 2 or 3 position into the corresponding hydroxylamino-methyl naphthalene, and rearranging by treatment with a dilute acid into a methyl-4-amino-1-naphthol. (3) By converting diazotization and hydrolyses a 1-aminonaphthalene having a methyl group in the 2 or 3 position into the corresponding 2-, or 3-methyl- 1-naphthol and introducing an amino group into the 4-position by coupling with a diazotized arylamine and catalytically reducing the coupled product at the diazo linkage to obtain the corresponding methyl-4-amino-1-naphthol. (4) The 3-methyl -4-amino-1-naphthol is made by converting a salt of 1-amino-2-methyl-naphthalene into 3-methyl-4-amino-1 naphthalenediazobenzene sulphonic acid, acylating, adding an alkylamine, reducing, diazotizing and hydrolysing. In examples (1) 2-methyl-1 : 4-naphthaquinone is converted into its monoxime and this is reduced with hydrogen in the presence of a platinum oxide catalyst, to give, after the addition of hydrochloric acid, the hydrochloride of 1-methyl-4-amino-1-naphthol which may be converted into the free base on treatment with caustic alkali. Sodium hydrosulphite may be substituted for the catalytic hydrogenation if desired. Other salts than the hydrochloride are also described including the tartrate, nitrate, oxalate, malate and citrate. The free base may be put up in a vegetable oil solution such as olive, peanut or cocoanut oil as an antihaemorrhagic agent. (2) 1-Amino-2-methyl naphthalene hydrochloride is added to diazotized sulphanilic acid in aqueous solution, treated with alkali to give the sodium salt, acylated with acetic anhydride, treated with acid to give 3-methyl-4-acetylamino-1-naphthalene diazobenzene sulphonic acid. and with ethanolamine to precipitate the ethanolamine salt which is reduced in alcohol solution with hydrogen in the presence of a Raney nickel catalyst to 3-methyl-4-acetylamino-1 - naphthylamine and finally diazotized, hydrolyzed and neutralized to 3-methyl-4-amino-1-naphthol. (3) 1-Nitro-2- methyl naphthalene is treated with zinc and ammonium chloride in aqueous solution to give 1-hydroxylamino-2-methyl-naphthalene which on treatment with a dilute acid to rearrange itself to form 3-methyl-4-amino-1-naphthol. (4) as in example (3) using the 3-methyl compound. (5) 1-Amino-3-methyl naphthalene is treated with sodium nitrite in dilute sulphuric acid solution, then with more concentrated sulphuric acid to convert the diazo-compound into 3-methyl-1-naphthol. This is treated in sodium hydroxide solution with diazotized sulphanilic acid and the coupled product acidified with hydrochloric acid and precipitated with ethanolamine as the ethanolamine salt. Finally by a catalytic reduction with hydrogen in alcohol solution using a Raney nickel catalyst, there is obtained 4-amino-3-methyl-1- naphthol. (6) The starting material of example (2) is treated according to the process of example (5 ) to give a product identical with that obtained in example (1) and isomeric with the product of example (2).