CS260153B1 - Process for preparing 2-amino-N- (1-methylethyl) benzamide - Google Patents

Abstract

Preparation of 2-amino-N-(1-methylethyl)benzamide, a prospective component for the preparation of the herbicide Bentazon. The essence of the method is that anthranilic acid reacts with isopropylamino acid and phosphorous chloride in an environment of organic solvents such as aromatic liquid hydrocarbons such as benzene, toluene, xylene in the temperature range of 5 °C to 180 °C.

Description

260153

The present invention provides a process for preparing 2-amino-N- (1-methylethyl) benzamide. 2-amino-N- (1-methylethylbenzamide is a potentially useful precursor for the preparation of the herbicidal preparation of Bentazone (Zeidler A., Fischer A., Weiss G .: NSR 1 542 836 [1966]; OXON, Italia, Eur., Pat. No. 70,467 [1981]; Merkle H., NSR Pat., 2, 710, 382 [1978]] This is a world-class top quality product that is widely used in agricultural practice. N- (1-methylethyl) benzamide is the subject of several washing machines (Staigner R. et al .: J. Org. Chem. 18,1 427, 1953; Jacobs R .: J. Heterocyclic Chem.7, 1 337, 1970] as well as several patents (Eur. Pat. 57 424, 1982; NSR Pat. 27 19 020],

The principle of the preparation of 2-amino-N- (1-methylethylbenzamide according to the invention is that the anthranilic acid is reacted with isopropylamine and PCl3 (phosphorous trichloride) in an organic solvent medium such as aromatic liquid hydrocarbons and benzobenzene, toluene, xylene in the range of 5 ° C to 180 ° C.

The reaction follows the scheme:

COOH 2 'CH, CH, z * CH-NH'

, -CO-NH-CH - ^ 2I O LNHz + CH3 \ t

+ 3 CH-NH 2. HCl + HO - PO CH 3 The advantage of the process for the preparation of 2-amino-N- (1-methylethyl) benzamide according to the invention is that the synthesis is a one-step, starting material is anthranilic acid which is readily available and the product obtained is a high yield (70-95 ° C) and high purity (98-99.8%). The isopropyl-amine hydrochloride formed can be recycled and isopropylamine can be recycled or used for the synthesis of e.g. its chloride.

The following examples illustrate, but do not limit, the invention. Example 1 295 g (5 mol) of isopropylamine are added at 5 ° C to 10 ° C to a vigorously stirred solution of 137.5 g (1 mol) of PCl 3 in 3,000 ml of toluene over 30 min. the mixture is heated for 10 min to 130 ° C and after cooling the precipitated isopropylamine hydrochloride is filtered off in the absence of air humidity (preferably under a protective nitrogen or argon atmosphere). The resulting solution is mixed with 274 g anthranilic acid and heated to 130 ° C to 150 ° C with vigorous stirring for 2 h. The precipitated metaphosphoric acid is gradually separated from the spercurator and, after cooling to 5 ° C, 340 g of crystalline material are obtained, which is washed on the filter with 1 N NaCO 3 to give a basic filtrate reaction. 250 g of a white crystalline solid, 2-amino-N- (1-methylethyl) -benzamide, m.p.

As in Example 1, but without filtering off i-propylamine hydrochloride, 274 g of crystalline anthranilic acid i was added once, and the solution was heated to boiling for 5 h, and cooled to 90 ° C was discharged to 2000 ml. After thorough addition, the aqueous layer is separated and the organic is mixed with 500 ml of water and 50 g of NaOH at 40 ° C. After separation of the aqueous layer, it was cooled to 5 ° C. 280 g of 2-amino-N- (1-methylethyl) benzamide are obtained, m.p. 145-146 ° C. Example 3

In Example 1, in xylene, 270 g of 2-amino-N- (1-methylethyl) benzamide was obtained after 2 h. Example 4

As in Example 1 in benzene, 200 g of 2-amino-N- (1-methylthyl) benzamide are obtained after 4 hours of boiling. Example 5

As in Example 1, 137 g of anthranilic acid is added and after 2 h boiling, 170 g (95% of anthranilic acid) of the amide are obtained with a melting point of 145-146 ° C.

Claims (2)

260153 SUBJECT MATTER 1. The process for preparing 2-amino-N- [1-methylthyl] benzamide of the formula is reacted with isopropylamine of formula CH3 CH-NH2 CH3 CO-NK-CH NH? CH, and phosphorous trichloride of formula PCl3 in the medium of organic solvents such as aromatic liquid hydrocarbons such as benzene, toluene, xylene in the range of 5 ° C to 180 ° C. characterized in that the anthranilic acid formula COOH NH. 4