CS232312B1 - Process for preparing 1-naphthol - Google Patents

Abstract

A method for producing 1-naphthol by treating a mixture of 1-naphthylamine monosulfonic acids, preferably obtained by sulfonation of naphthalene at 5 to 160 °C, nitration of the resulting naphthalene sulfonic acids and reduction of nitronaphthalene sulfonic acids, with aqueous mineral acids at 130 to 280 °C, optionally under elevated pressure. 1-naphthol is one of the basic intermediates in dye chemistry and the new method of its production replaces the classical method of preparation from 1-naphthylamine, in which technology the accompanying carcinogenic 2-naphthylamine was present.

Description

The present invention relates to a process for the preparation of 1-naphthol from a mixture of naphthylamine sulfo acids obtained by sulfonating naphthalene, followed by nitration and reduction.

Prior art processes for the preparation of toluene and toluene involve the substitution of a sulfo- or amino group with hydroxyl. For example, 1-naphthylamine is heated with dilute sulfuric acid to be converted to 1-naphthylamine. Alkaline melting of naphthalene-1-sulfonates yields 1-naphthol as in the case of the preparation of 2-naphthol from naphthalem-2-sulfonates. The main difficulty of these syntheses is the difficult preparation of sufficiently pure primary intermediates. Thus, for example, the mononitration of naphthalene produces mainly 1-nitronaphthalene, but also always the 2-nitroisomer and other impurities; the crude 1-nitronaphthalene produced has a pour point between 52.0 to 52.5 ° C, after crystallization from solvent naphtha the product has a pour point of 54.4 ° 0, while the pure preparation has a melting point of 61.0 ° C. Similarly, in the case of various alternatives to the monosulfonation of naphthalene, in addition to the predominant naphthalene-1-sulfoisomer, a 2-sulfonated derivative is obtained; Here too, refining is difficult. Necessary purification processes, such as crystallization of sulfoderivatives or recrystallization or extraction and distillation of nitro products, are expensive, they adversely affect the economics of the process, but without their application, 1-naphthol is still unsatisfactory. In addition, in the alternative of treating 1-naphthylamine contaminated with kercionogenic 2-naphthylamine, the technology is hazardous to the operator.

Now he was lying? Process for preparing 1-naphthol according to the invention, characterized in that a 3-mixture of 1-naphthylamino-monosulfonic acids, preferably obtained by sulfonating naphthalene at 5 to 160%, by nitrating the resulting naphthalenesulfonic acids and reducing nitronaphthalenesulfonic acids, is treated. aqueous mineral acids at 130 to 280 ° C, optionally at elevated pressure up to 6500 kPa. By treatment with aqueous mineral acids at temperatures of 130 to 280 ° C, the amino groups are converted to hydroxyl and the sulfo groups are cleaved off.

The process is based on naphthalene and relies on malt by the reactions shown in the diagram on the next page.

In monosulfonation in sulfuric acid, conducted under reaction conditions favoring the formation of 1-sulfoisomer, followed by mononitration with reduction, said naphthylamine sulfonic acids are present in approximately X: II: III: IV ei ratios of 66: 20: 7: 7 to 70: 26: 2 : 2 and in cases where the monoaulfonation is conducted to position 2, the approximate ratio is I: II: III:

: IV ftí 10: 3: 43: 43 The scheme shows that nitrogen is always bonded in the elf position on the naphthalene core, so that the final hydroxyl is always in the alpha position; the sulfo groups are simultaneously cleaved under the action of the aqueous mineral acids by which the substitution takes place. The possibility of contamination of the 1-naphthol produced according to the invention with 2-naphthol is almost eliminated.

In technical practice, it is advantageous to select the reaction conditions for moaosulfonation so as to produce a maximum amount of naphthalene-1-sulfoacid, since alpha sulfo cleavage is easier in the final synthesis phase than beta sulfo groups. Mixtures of naphthylamine sulfoacids, as they have been found in the production of Peri-cyanoic acid and Laurentic acid, or mixtures of isomers accompanying the production of Cléve acids, can be used for the novel process for the production of 1-naphthol without prior separation. Among the mineral acids suitable are: hydrochloric, hydrobromic, sulfuric and phosphoric acid.

Only seemingly the new synthesis appears to be more complicated when compared to the process starting from 1-naphthylamine, where the required 1-nitronaphthalene is obtained so as to 1 part ha. naphthalene uses a total of about 3.3 parts by weight. sulfuric acid 100% (which diluted serves as the reaction medium for nitration) and nitric acid equivalent. In the process according to the invention, in principle part of the sulfuric acid used is used as the sulfonating agent and the residual sulfuric acid is used as the reaction medium for subsequent nitration. Thus, the new technology does not differ significantly from the consumption of 1-naphthol via 1-naphthylamine in terms of raw material consumption standards. Other technical parameters of production are 3-suits, but purity of 1-naphthol, suffonation

reduction h ₂ n with ₃ h ίθώ

SO, H

H, N

SO-H] o] LPJA

NH ₂ iV

OM

NovýmοΤο] obtained by the new procedure is incomparable better. The proportion of sulfuric acid consumed in the sulphonation of naphthalene can be used as a mineral acid to facilitate the conversion of the amino group to the hydroxyl, and the amount of the mineral acid can be reduced by removing the sulfo groups. A technologically advantageous alternative is to produce 1-naphthol by heating the final reaction mixture, which is lysed after sulfonation of the naphthalene, followed by nitration and reduction in sulfuric acid, e.g. by metal powders. or by the addition of concentrated sulfuric acid to 10 to 70%. _Q

An example of a stirrer and thermometer rubbed autoclave is charged with 65 g of a mixture consisting of 45.5 S of 1-naphthylamine-8-sulfonic acid and 19.1 g of 1-naphthylamine-5-sulfonic acid, added 90 ml of 22% HgSO4. , the autoclave is sealed and the contents heated to 195 ° C (note: during heating, by opening the autoclave vent valve, steam is released with air, which is repeated 3 times). The contents of the autoclave are maintained at 195 ° C for 23 hours, then allowed to cool freely to 100 ° C, vented, 90 ml of water are added, the mixture is stirred and filtered.

After washing with water and drying, 38.7 g of crude 1-naphthol, i.e. 91.6% of th, is obtained. 2-Naphthol was not detected in the product.

Claims (1)

SUBJECT OF THE INVENTION Process for the preparation of 1-naphthol, characterized in that a mixture of 1-naphthylamine monosulfonic acids, preferably obtained by sulfonating naphthalene at 5 to 160 ° C, nitrating the resulting naphthalenesulfonic acid and reducing nitrophthalenesulfonic acids, is treated with aqueous mineral acids at 130 to 280 ° C, optionally at elevated pressure up to 6500 kPa.