SU642301A1 - Method of obtaining o-, p- m-aminobenzonitriles - Google Patents

Description

The invention relates to a new process for the preparation of O-, p- or w-aminobenzonitriles, which are used as intermediates in the synthesis of a number of physiologically active substances, dyes. A method of producing 4-aminobenzonitrile is known, in which monoacetate phenylenediamine is treated with sodium nitrite, the diazonium salt obtained is reacted with cyanic copper, and then treated with sulfuric acid l. In addition, a method is known for preparing o-, p- or l-aminobenzonitriles, which means that the corresponding nitrobenzonitrile is reduced by hydrogen under pressure at a temperature of DO-C in the presence of a nickel catalyst. with a mixture of hydroxylamine hydrochloride and pyridine in the presence of acetic anhydride 2. A disadvantage of the known methods is their multi-stage and labor-intensive and comparative inaccessibility of the starting compounds. The aim of the invention is to simplify the process and expand the raw material base. This goal is achieved in that methyl ether / o-, p- or AL-nitrobenzoic acid is reacted with ammonia under a pressure of 7-10 at a temperature of 340360 ° C in the presence of -y-alumina. The desired product is isolated with a yield of 60-65% of theory. The proposed method is catalytic, there are no intermediate stages and the target product is the direct product of the reaction. In this method, in one stage, the nitro group is reduced on a heterogeneous catalyst and the ester group is replaced by a nitrile one. The advantage of this method is that the quality of the starting product for the production of l-aminobenzonitrile can be used from industrial production of dimethyl terephthalate, methyl benzoate, and the catalyst is a generally available and cheap catalyst - alumina. The process is carried out in a flow type installation.

Example 1..18.1 g (0.1 mol) of p-nitrobenzoic acid methyl ester is passed with a bulk velocity of 0.24 h over the catalyst, .AEg 3 heated to 350 ° C, under an ammonia pressure of 10 at. After crystallization, 7.55 g (64% based on p-nitrobenzoic acid methyl ester) p-aminobenzonitrile is isolated. M.p. 85-86 ° C.

Nitrogen content,%: calculated 23.72; found 23.59.

Example 2, 18.1 g (0.1 mol of o-nitrobenzoic acid methyl ester is passed fc with a bulk velocity of 0.25 h over a catalyst heated to 355 ° C under an ammonia pressure of 9 atom. 7.1 g (60% % (based on o-nitrobenzoic acid methyl ester) o-aminobenzonitrile methyl ester, mp 6970 ° C.

.Nitrogen content,%: calculated 23.72; found 23.61.

Example 3. 18.1 g (0.1 mol) of ll-nitrobenzoic acid methyl ester is passed with a bulk velocity of 0.24 h over a catalyst DE OJJ heated to 350 ° C under an ammonia pressure of 9 at. Crystallization isolated 8.1 g (68% based on L-nitrobenzoic acid methyl ester) of L-aminobenzonitrile. M.p. 53-54C.

Nitrogen content,%: calculated 23.72; found 23.67,

Claims (2)

1.Bogoslovsky V.M. About receiving anisal aminobenzonitrile. JOH, 8, 1938, p. 1784-1785. 2. German patent number 523273, cl. 12 C}, 6/02, 1927.