CS206092B1 - Method of isolation of the disazocondensing pigments - Google Patents

Description

(54) Method for isolating disazocondensation pigments

The invention relates to a process for the isolation of disazocondensation pigments prepared by reacting an arylazocarboxylic acid halide with an aromatic diamine.

High-value disazocondensation pigments are prepared by reacting an arylazocarboxylic halide, especially arylazonaphthoic acid, with the corresponding aromatic diamine in a molar ratio of 2: 1. The reaction is carried out in an indifferent anhydrous organic solvent at elevated temperature. The pigment is isolated from the reaction mixture by filtration at a temperature above 110 ° C, then washed with a hot solvent, followed by an alcohol mixed with water and finally optionally with water. The aqueous filter cake is dried in a suitable oven. The procedure for the preparation of disazocondensation pigments is described in patents, e.g. No. 142857, 143 034, 146444, Cs. aut. osv. No. 154505, 155048, 162342, U.S. Pat. 2518560, Switzerland. U.S. Pat. 297 020, 303155, 304 984, 305 028, 397 913, etc.

A disadvantage of the prior art methods is the difficulty in isolating the pigment from the reaction mixture after condensation of the arylazocarboxylic acid chloride with the aromatic diamine. In order to obtain an application-friendly dye, all soluble by-products must be removed from the pigment. This is achieved by thoroughly washing the pigment with an indifferent organic solvent at a temperature above 110 ° C, which places high demands on the construction materials of the separation equipment and, moreover, increases the risk of contamination of the working environment with hot solvent vapors. The amount of solvent required to thoroughly wash the pigment is very high, thereby increasing the cost of its regeneration. Thus, from an environmental and safety point of view, the prior art method of isolating disazocondensation pigments is very demanding and disadvantageous.

Research has now found that these disadvantages are overcome by the isolation method disazo206092

206 092 condensation pigments according to the invention, characterized in that the reaction mixture after condensation of the azocarboxylic acid halide of the general formula

wherein A, B, C. D is hydrogen, methyl, chloro, methoxy, trifluoromethyl, NO ₂ , CONH ₂ , COOCH _3, and X is chloro or bromo, with an aromatic diamine of formula nh ₂

A • NH (II)

B wherein A. B are as defined above and the amino groups are in meta or para-position to each other, the condensation being carried out in an organic solvent at a temperature of 90 ° C to 170 ⁼ C, treated with a cycloaliphatic amine of formula nh ₂ wherein R is H or an alkyl of 1 to 5, or a polyamine of the formula γ- (CH ₂ ) _m -nh ₂ (IV) · wherein R is hydrogen or an alkyl of 1 to 6, m-2 or 3, in an amount of 10 to 100 wt% per pigment, at a temperature of 40 ° C to 120 ° C, the pigment is then separated by filtration or centrifugation and washed with methanol or ethanol.

The condensation of the azocarboxylic acid halides with the aromatic diamine is carried out in an organic solvent environment such as toluene, xylene, chlorobenzene, dichlorobenzene, trichlorobenzene, chlorotoluene, nitrobenzene etc. at a temperature of 90 ° C to 170 ° C. After condensation, the reaction mixture of the invention is treated with a cycloaliphatic amine such as cyclohexylamine, N-cyclojexyl-1,3-propanediamine, etc. in an amount of 10% to 100% by weight. to a pigment at a temperature of 40 ° C to 120 ° C. The mixture is maintained at this temperature preferably with stirring for, for example, 0.1 to 5.0 hours. Then, the disazocondensation pigment is isolated by filtration on, for example, a vacuum or pressure suction or a calibrating press or a filter press. by centrifugation, at a temperature of 40 ° C to 100 ° C. The product is washed with an alcohol blending indefinitely with water such as methanol, ethanol, propanol or butanol. The resulting azocondensation pigment can then be washed with water and dried in a suitable drying apparatus.

By the action of the cycloaliphatic amine in the reaction mixture after the condensation of the azocarboxylic acid halide with the aromatic diamine, the solubility of the by-products of the condensation reaction is substantially increased. Separation of the resulting pigment in the reaction mixture can then be carried out at a temperature of 40 ° C to 100 ° C and the product obtained need not be washed with any hot organic solvent at all, as was done in the prior art. The process of isolation of the disazocondensation pigments of the present invention eliminates the difficulties of product separation and reduces the separation equipment requirements. The indifferent organic solvent was used in the new process

208 092 also uses insulation only as a condensation reaction medium. The process according to the invention also significantly improves the synthesis of disazocondensation pigments from an environmental and safety point of view. The resulting pigments have good coloristic properties (pure hue, good spreading) and are resistant to migration.

The process for isolating the disazocondensation pigments of the invention is illustrated in the following examples.

EXAMPLE 11 747 g of o-dichlorobenzene and 7.6 2,5-dichloro-1,4-phenylenediamine [i] were charged to the digester and heated to 60 ° C with stirring. Then, 47.8 g of 1- (2,5-dichlorobenzenazo) -2-hydroxy-3-naphthoyl chloride was added and the mixture was kept at 60 ° C for 60 minutes with stirring. Further, the digester temperature was raised to 145 ° C and held for 180 minutes to complete the condensation reaction. Then the temperature of the reaction mixture was lowered to 115 ° C, introduced into the digester; 24 g of cyclohexylamine were stirred at 110 ° C to 120 ° C for 120 minutes. The contents of the digester were cooled to 60 ° C and filtered on a vacuum pad. The cake was washed with 750 ml of ethanol and 700 ml of water. The product was dried at 80 ° C to 90 ° C to constant weight. The resulting pigment had good spreading and pure shade in oil paint and PVC and was stable in migration.

Example 2

G of N-cyclohexyl-1,3-propanediamine was added to the suspension after the condensation reaction as in Example 1, and the mixture was stirred at 90 ° C for 120 minutes. At this temperature, the suspension was filtered and the product washed with 750 ml of ethanol and 750 ml of water. The wet cake was dried at about 90 ° C. The product had very good coloristic properties.

Example 3

As in Example 1, 23.9 g of 1- (2,5-dichlorobenzenazo) -2-hydroxy-3-naphthoyl chloride were condensed with 3.24 g of 1,4-phenylenediamine in an environment of 343 g of o-dichlorobenzene. The reaction mixture was then stirred with 21 g of N-cyclohexyl-1,3-propanediamine at 90 ° C to Γ00 ° C for 120 minutes. The suspension was then cooled to 50 ° C and filtered on a vacuum pad. The cake was washed with 250 mL of ethanol and 250 mL of water. The dried product had very good coloristic properties and was stable in migration.

Claims (1)

SUBJECT OF THE INVENTION Wherein A, B, C, D are hydrogen, methyl, chloro, methoxy, trifluoromethyl, NO ₂ , CONH ₂ , COOCH ₃ 'and X is chloro or bromo, with an aromatic diamine of the formula nh ₂ . -nh ₂ (II) 4 ' 206 092 wherein A, B are as defined above and the amino groups are in meta- or parapolysis with each other, the condensation being carried out in an organic solvent medium, characterized in that the reaction mixture after the condensation is treated with a cycloaliphatic amine of the formula -j ''<V-NH ₂ (III) · i where R is hydrogen or alkyl of 1 to 6 carbons, or a cycloaliphatic polyamine type _{(CH2) m} -NH ₂ (IV) wherein R is as defined above % am-2 or 3, in an amount of 10 to 100 wt. to pigment, at a temperature of 40 ° C to 120 ° C, and after separation, the pigment is washed with methanol or ethanol.