CS231885B1 - purification of 2-hydroxy-3- (3-ureido-N-phenyl) naphthamide - Google Patents

Abstract

The invention relates to a method for purifying 2-hydroxy-3-/3-ureido-N-phenyl/-naphthamide, prepared by reacting 2-hydroxy-3-naphthoyl chloride with 3-aminophenylurea in a heterogeneous medium in the presence of surfactants, for example alkyl polyglycol ethers. The crude product is often contaminated with reaction by-products and must be subjected to a refining process for dyeing purposes. The previous purification method by dissolving in 0.2% by weight hydrochloric acid was not very effective and did not allow obtaining a product of the required quality. The process according to the invention allows the reaction by-products to be reliably removed by washing in an ammoniacal aqueous medium and a solution of ammonium salts at pH 8.5 to 10 under the action of surfactants, for example alkyl polyglycol ethers, at 80 to 100 °C, filtration and washing of the product.

Description

The present invention relates to a process for the purification of 2-hydroxy-3- (3-ureldo-N-phenyl) -naphthamide.

The present method of purification of 2-hydroxy-3- (3-ureido-N-phenyl) -naphthalide by washing in 0.2% hydrochloric acid, filtration and washing with water has not been effective and did not remove the accompanying impurities from the synthesis of crude product of dyeing quality the blank was not suitable.

These disadvantages are eliminated by a method of purification of 2-hydroxy-3- / 3-ureido-phenyl-N / naphthamide technical type disperser, in the presence of nonionic detergents such as alkyl polyglycol ethers such as ethylene condensates Ig ^H 37- ^C / ^O- C ^H 2 ^-CH 2 ^{/ R2} O ^OH 'which is the subject of the invention whose principle consists in that the cleaning is done in an aqueous ammonia environment in which may be optionally replaced Some ammonia ammonium salt such as chloride, sulphate or carbonate at a pH of 8.5 to 10 and a temperature of 80 to 100 ° C, followed by stirring the reaction mixture, filtering and washing the product.

The following examples illustrate the process without limiting the scope of the invention.

Example 1

1200 l of water are introduced into the enameling boiler with stirring, 120 kg of crude 2-hydroxy-3- (3-ureido-N-phenyl) -naphthamide are introduced in the form of a 40% aqueous paste, 20 l of 25% ammonia water are allowed. % alkyl polyglycol ether and 6 kg of C ₁₈ H ₃₇ - / O-CH ₂ -CH ₂ / _2O -OH.

The boiler is sealed, the reaction mixture is heated to 85 ° C and kept at this temperature for 2 hours, then filtered on a filter press and washed with 400 L of 60 ° C warm water.

110 kg of 2-hydroxy-3- (3-ureido-N-phenyl) -naphthamide pure 100% are obtained.

Example 2

The second exemplary embodiment of the invention is similar to the first exemplary embodiment except that 15 l of 25% by weight ammonia water is used instead of 20 l of 25% by weight aqueous ammonia together with the addition of 3 kg of ammonium chloride and with the difference that the purification is performed instead of at 85 ° C at 90 ° C.

Claims (1)

Process for the purification of 2-hydroxy-3- (3-ureido-N-phenyl) -naphthamide in the presence of nonionic surfactant-type dispersants, for example ethylene condensates such as alkyl polyglycol ether C, _o H, _- / 0-CH.-CH - / - "- 0H, characterized in that the cleaning is performed in an aqueous ammoniacal tallow / 4 4 4Ό environment in which part of the ammonia can optionally replace ammonium salts such as chloride, sulfate or carbonate at pH 8.5 to 10 and 80 to 100 ° C, followed by stirring the reaction mixture, filtering and washing the product.