CS269517B1 - Process for producing 2-amino-N- [1-methylethyl] -benzamide - Google Patents

Abstract

The substance is used as an intermediate in the production of plant protection products. It is produced by reacting 2-amino-alkyl benzoates, where alkyl is methyl, ethyl, propyl, with isopropylamine. Sodium methyl, ethyl or propyl alcoholate are used as catalysts. The reaction is carried out at a temperature of 30 to 200°C in an autoclave. The reaction time depends on the selected temperature and varies from 0.5 to 25 hours. Yields above 80% of the theoretical product with a purity of 99% are achieved. The solution can be used in a chemical industry.

Description

The invention relates to a process for the production of 2-amino-N-(1-methylethyl)-benzamide, which is used as an intermediate in the production of plant protection preparations.

The literature describes a method of preparing 2-amino-N-[1-methylethyl]-benzamide by reacting isotonic anhydride and isopropylamine in water at a temperature of 48 to 50° C. and a reaction time of 4 hours in a 65% yield /3. Org. Chem. 18, 1427 /1953/ /. In 3. Heterocyclic Chem. 7, 1337 /1970/ an analogous procedure for the preparation of 2-amino-N-[1-methylethyl]-benzamide in the medium of N,N-dimethylformamide in a 90% yield is reported. In EP 0 057 424 the preparation of 2-amino-N-[1-methylethyl]-benzamide is described by the reaction of phthalic acid, dissolved in an aqueous solution of sodium hydroxide, with sodium hypochlorite and isopropylamine hydrochloride. The preparation of unsubstituted 2-aminobenzamide is also published /O.Chem. Soc. 861 /1945/ / by several shakings of methyl anthranilic acid ester with concentrated ammonia. However, an analogous reaction of methyl anthranilic acid ester cannot be carried out even by heating to 90 °C. However, CS A. 0. 229 090 aa states that a similar reaction of aminobenzoic acid esters with amines provides high yields if di-methoxy-2-propoxyaluminum is used as a catalyst. The disadvantage of this procedure is the use of a catalyst that is not readily available and is not produced industrially. Its price would also be significantly higher than the catalysts proposed in this document.

It has now been found that 2-amino-N-(1-methylethyl)-benzamide of formula I

can be prepared by reacting a 2-amino-alkylbenzoate of formula II with isopropylamine according to the reaction scheme '

ch-nh ₂

/11/ /1/ where R represents methyl, ethyl, propyl, by heating in an autoclave at 30 to 200°C, preferably at 110 to 150°C, in the presence of catalysts, which are alcoholates of formula III.

R-O-Na /111/ where R has the above-mentioned meaning. The molar ratio of catalyst to 1 mole of 2-aminoalkylbenzoate can vary in the range of 0.1 to 10 moles, preferably 1.5 to 2.5 moles. The catalyst can be recovered and reused after the reaction is complete. The molar ratio of isopropylamine to 1 mole of 2-aminoalkylbenzoate can vary in the range of 0.5 to 50 moles, preferably 1 to 4 moles. Excess isopropylamine can be recovered and reused. The heating time is temperature-dependent and can be from 0.5 to 25 hours, preferably from 5 to 12 hours.

The advantage of the process for producing 2-amino-N-(1-methylethyl)-benzamide according to the invention lies in the fact that the reaction times are short, the yields are high and the production process is simple.

Example 1

15.1 g (0.1 mol) of 2-aminomethylbenzoate was charged into an autoclave with a 250 ml reactor, a solution of sodium methoxide dissolved in 100 ml of methanol was added, and 24.0 g (0.42 mol) of isopropylamine was added to the mixture. After the reactor was closed, the reaction mixture was heated to 125-130 °C with stirring and this temperature was maintained for 5 hours.

CS 269517 Bl

After cooling to room temperature, the reaction vessel was opened and its contents were transferred to a 500 ml distillation flask. The volatile components were distilled off under atmospheric pressure. 300 ml of water was added to the solid residue. A suspension was obtained, from which the solid component was filtered off and evaporated. 15.7 g (approx. 97%) of the product was obtained, mp 148-151 °C. The product was dissolved in dilute hydrochloric acid, a small insoluble component was filtered off, and the product was precipitated from the filtrate with an aqueous solution of sodium hydroxide.

13.5 g of purified product were obtained, mp 147-148°C, containing 99.8% of 2-amino-N-(1-methylethyl)benzamide. The yield was 82.8% of theory, calculated as 2-aminomethylbenzoate.

Example 2

13.2 g (0.075 mol) of 2-aminoethylbenzoate was poured into an autoclave with a 250 ml reaction vessel, 8a, and sodium ethanolate was added, prepared from 3.5 g (0.15 mol) of sodium hydroxide dissolved in 100 ml of anhydrous ethanol and 17.4 g (0.29 mol) of anhydrous isopropylamine. After closing the reactor and starting the stirrer, the reaction mixture was heated to 125-130 °C, at which temperature it was maintained for 5 hours. After cooling to room temperature, the reactor was opened and its contents were poured into a 500 ml distillation flask. 150 ml of water was added to the reaction mixture in the distillation flask. The volatile components were distilled off under slightly reduced pressure, and the solid component was isolated from the aqueous suspension and dried. The thus obtained portion was dissolved in 100 ml of hydrochloric acid, diluted in a ratio of 1:9, and the insoluble residue was filtered off. The product was precipitated from the filtrate with 10% aqueous sodium hydroxide solution. The solid portion was isolated, washed with water and dried.

10.8 g of product were obtained, mp 148-150°C, containing 99% of 2-amino-N-(1-methylethyl)-benzamide. The yield was 76.0% of theory, calculated as 2-aminoethylbenzoate.

Claims (1)

SUBJECT OF THE INVENTION Process for the preparation of 2-amino-N-(1-methylethyl)-benzamide of formula I -CO-NH-CH^CH, -nh ₂ ^j /1/ by reaction of 2-aminoalkylbenzoates of formula II -CO-OR ^/IX/ [oj where R represents alkyl with 1 to 3 carbon atoms, with isopropylamine at a temperature of 30 to 200 °C, characterized in that alcoholates of the general formula III are used as catalysts R-O-Na /111/ where R is alkyl of 1 to 3 carbon atoms.