CS257824B1 - Method of 2-amino-n-(1-methylethyl)benzamide purifying - Google Patents

Abstract

The solution relates to the cleaning method 2- -amino-N- (1-methylethyl) benzamide for the purpose of removal of impurities, which are acidic substances, of a basic and neutral nature. The essence of the way Cleaning consists in being raw 2-Amino-N- (1-methylethyl) benzamide dissolved in water or organic solvents, heated aromatic hydrocarbons such as benzene, toluene, xylene, ethers such as diethyl ether, 1,2-dimethoxyethane, halogenated hydrocarbons as dichloromethane, 1,2-dichloroethane, chloroform, esters of acetic acid at room temperature boiling of the solvent was treated with 1 to 6 N aqueous a solution of basic agents such as carbonates, alkali hydrogen carbonates and hydroxides metals and alkaline earth metals up to neutral reaction after separation of aqueous solutions of basic agents to the organic phase with activated charcoal at 0.2 to 3% wt. to the weight of the crude product at temperature boiling of the solvent, insoluble matter filtered and the filtrate cooled to room temperature 0 to 10 ° C, optionally concentrated to crystallization.

Description

The invention relates to a process for purifying 2-amino-N- (1-methylethyl) benzamide.

2-Amino-N- (1-methylethyl) -bezamide is a potentially useful precursor for the preparation of Bentazone (Zeldler A., Fischer A., Weiss G .: NSR Pat. 1 542 836 (1966); OXON, Italia, Eur. Pat. No. 70,467 (1981), Merkle R. et al., U.S. Pat. No. 2,710,382 (1978)), a herbicidal preparation which is widely used in agricultural practice.

The preparation of 2-amino-N- (1-methylethyl) benzamide is the subject of several works (Staigner R. all .: J. Org. Chem. 18, 1427, 1953; Jacobs S .: J. Heterocyclic Chem. J, 1337) (1970) as well as several patents (Eur. Pat. 57,424, 1982; Germany Pat. 2,719,020).

However, 2-amino-N- (1-methylethyl) benzamide for application is required in such a form that it is as pure as possible and does not decompose in use, free of acidic components such as anthranilic acid, phthalic acid, hydrochloric acid, phosphoric acid. etc., nor the basic and neutral components such as anthranilic and phthalic acid salts, phthalimide, phthalic acid amides ... etc, as impurities. However, the method of its purification has not been described in the literature.

This disadvantage is substantially eliminated by the purification method of 2-amino-N- (1-methylethyl) benzamide of the formula

CO-NH-CH-CH

I, CH ₃ NH ₂ according to the invention, which is characterized in that the crude 2-amino-N- (1-methylethyl) benzamide dissolved in water or an organic solvent selected from aromatic hydrocarbons such as benzene, toluene, xylene, ethers, such as diethyl ether, 1,2-dimethoxyethane, halogenated hydrocarbons such as dichloromethane, 1,2-dichloroethane, chloroform, acetic acid esters at the boiling point of the solvent are treated with a 1 to 6 N aqueous solution of basic agents such as carbonates, bicarbonates and hydroxides of alkali metals and metals The organic phase is treated with activated carbon in an amount of 0.2 to 3% by weight of the organic phase after neutralization of the aqueous solutions of the basic agents. to the weight of the crude product at the boiling point of the solvent, the insoluble matter is filtered off and the filtrate is cooled to 0-10 ° C, optionally concentrated to crystallize.

Extraction with basic agents removes impurities of acidic and alkaline character and subsequent treatment with activated carbon also removes neutral substances.

The product according to the invention yields a product with a purity of 98 to 99.8% of active ingredient.

Example 1

100 g of 2-amino-N- (1-methylethyl) benzamide (90% active ingredient) are dissolved in 1000 ml of toluene at the boiling point of the solvent and after washing with 1 N sodium carbonate solution is boiled with 2 g of activated carbon. After hot filtration, the filtrate was cooled to 10 ° C. The precipitated white crystalline solid is filtered off and washed with 100 ml of toluene. After partial concentration, additional portions of 2-amino-N- (1-methylethyl) bezamide are obtained. 90 g of 2-amino-N- (1-methylethyl) benzamide of 98% active substance are obtained at 7 ° C. Mp 149 ° C.

Example 2

100 g of 2-amino-N- (1-methylethyl) benzamide (96% active ingredient) are dissolved in 1000 ml of diethyl ether and, after neutralization with 6 N sodium hydroxide, the ether layer is left for 5 min. boil with 0.2 g of activated carbon. After insoluble ether was filtered off, it was distilled off under vacuum. 92 g of 2-amino-N- (1-methylethyl) benzamide having a purity of 98% are obtained at 10 DEG C. m.p. t. Mp 149 ° C.

Example 3 3 g of 2-amino-N- (1-methylethyl) benzamide (80% active ingredient) are dissolved in 1000 ml of water and 20 ml of 1,2-dimethoxyethane at the boiling point of the solvent. After adding 1 N potassium hydroxide to the neutral reaction and boiling with 0.2 g of activated carbon, insoluble matter is filtered off from the solution to give 2-amino-N- (1-methylethyl) benzamide of 99.5% purity at 5 ° C, tt Mp 149 ° C.

Example 4 g of 1-amino-N- (1-methylethyl) benzamide (80% active ingredient) is dissolved in 100 ml of dichloromethane with addition of 1 N calcium hydroxide until neutral. After boiling the dichloromethane solution with 0.2 g of activated carbon, 7 g of 2-amino- (1-methylethyl) benzamide are obtained at 3 DEG C. EXAMPLE 5 g of 2-amino (1-methylethyl) benzamide (85% active ingredient) are obtained. Dissolve at 60 ° C in 100 mL ethyl acetate. After neutralization with 2 N calcium hydroxide, the organic phase is 5 min. It is boiled with 0.3 g of activated carbon and, after filtration at 5 DEG C., 7 g of 2-amino-N- (1-methylethyl) benzamide of 99% purity are obtained, m.p. Mp 149 ° C.

Example 6

000 g of 2-amino-N- (1-methylethyl) benzamide (95% active substance) is dissolved in 10 000 ml of toluene and 1 000 ml of 1,2-dimethoxyethane at 100 ° C and after washing with 1 N calcium milk Ca ( OH) ₂ was boiled for 5 min. with 30 g of activated carbon. After hot filtration and concentration to half volume, 750 g of 2-amino-N- (1-methylethyl) benzamide is obtained at 5 ° C with a purity of 99.5%. From the mother liquor, after distilling off 400 ml of solvent, an additional 200 g of 99% efficacy was obtained.

EXAMPLE 7 g 2-Amino-N- (1-methylethyl) benzamide (95% active ingredient) was dissolved in 1000 ml of water at 100 ° C. After neutralization! Boil with 1 N NaOH for 10 min. with 0.5 g of activated carbon and after hot filtration and cooling to 3 ° C gives 9 g of 2-amino-N- (1-methylethyl) benzamide of 99.5% purity and m.p. Mp 149 ° C.

Claims (1)

Process for purification of 2-amino-N- (1-methylethyl) benzamide of formula CO — NH-CH — CHg NH ₂ containing not more than 20 i impurities which are acidic alkaline and neutral, characterized in that, for crude 2-amino-N- (1-methylethyl (benzamide dissolved in water or organic solvents) selected from the group of aromatic hydrocarbons such as benzene, toluene, xylene, ethers such as diethyl ether, 1,2-dimethoxyethane, halogenated hydrocarbons such as dichloromethane, 1,2-dichloroethane, chloroform, acetic acid esters at the boiling point of the solvent are treated with a 1 to 6 N aqueous solution of basic agents such as carbonates, alkali metal and alkaline earth metal bicarbonates and hydroxides, until neutral, after separation of the aqueous bases, the organic phase is treated with activated carbon in an amount of 0.2 to 3% by weight on the weight of the crude product at the boiling point of the solvent, the insoluble matter is filtered off and the filtrate is cooled to 0-10 ° C, optionally concentrated to a residue yštalizácii.