CS236118B1 - Single-stage method of symmetrical metal-complex dye stuff preparation - Google Patents

Description

The present invention relates to a one-step process for the preparation of symmetrical metal-complex dyes by simultaneous azocopulation and chromation.

Hitherto known methods for the preparation of said metal-complex azo dyes consist in the action of chromating agents such as formic chromium, chromium acetate, chromium sulphate or potassium-potassium sulphate and chromsalicic acid on preformed azo dyes of the corresponding constitution (Brit.pat.

740 589; 747 872; 813 186; US Pat. No. 2,871,232) or by treating the above-mentioned azo dyes (AO 187 288-90; pretreated metal-complex azo dyes at a molar ratio of 1: 1);

187 149-50), wherein the chromation process is normally carried out at high temperature and pressure for 8 to 40 hours. Apart from this, the preparation of the starting azo dyes corresponding to the starting diazotization components III and IV is clearly carried out only in the presence of ZnCl2, which is also commonly used for the preparation of these azo dyes.

It has now been found that said dyes can be prepared by a one-step process in the presence of chromium ions in the form of alkaline chromates III or a mixture of chromium ions and chromium VI by simultaneous azocopulation and chromation to form 2: 1 metal-complex azo dyes. In the reaction system, a high effective charge value of the central chromium ions, including their small ionic radii, is favored, causing considerable polarization of the interacting free electron pairs of the resulting azo dyes stabilizing the central atom by the intramolecular process to form a stable coordinating compound.

The one-step process for preparing 2: 1 synthetic metal complex dyes according to the invention consists in the simultaneous reaction of equi2.

236 118 molar amounts of the starting diazotization components of formulas III and IV

(IV)

and neutral and alkaline ions in the presence of ammonia at temperatures of 23 to 100 ° C. It is advantageous to use alkali metal dichromates or chromates, optionally in admixture with chromium salts, as the chromating agent. Their concentration may be higher than the stoichiometric ratio, since under the reaction conditions only the formation of 2: 1 coordination azo compounds is preferred.

The alkalinity of the reaction medium can range from pH 6.0 to 12, preferably from 8.5 to 10.5, and the reaction medium must contain ammonium ions in a concentration corresponding to two to ten times the molar concentration of chromium ions. azo dye formation rate and corresponding coordinating azo compound ·

Furthermore, can favorably influence the speed of reaction, and choice of the reaction temperature which is preferably varied within a temperature interval of 85 ^U C, the reaction rate increases with increasing temperature. Under these reaction conditions, the total reaction time does not exceed 4 to 8 hours, when the starting components are quantitatively transformed to the desired 2: 1 metal-3 236 118 complex dye. Due to the high selectivity of the chemical transformation and the very low content of inorganic salts, it is not necessary to isolate the resulting dye from the reaction mixture. The farcous form of the dye is obtained directly by drying the reaction mixture in a spray drier, optionally with the prior addition of an emulsion of suitable oily substances imparting a non-dusting treatment to the dried dye.

The preparation of the 2: 1 metal complex azo dyes according to the invention is further illustrated by the following examples, but not by way of limitation.

Example 1 mol of 2-naphthol is dissolved with 1 mol of NaOH in 1500 ml of water and 0.125 mol of potassium dichromate and 0.25 mol of potassium chromite sulfate are added. The reaction mixture was further charged with 1 mole of 1-diazo-2-naphthol-4-sulfoacid and 300 ml of a 26% aqueous ammonia solution and heated to reflux at 80-90 ° C for 6-8 hours. This gives the corresponding 2: 1 metal-complex dye which dyes wool and polyamide with a gray-blue hue.

EXAMPLE 2 2 mol of 2-naphthol is dissolved in 1 500 ml of water with 1.1 mol of sodium hydroxide and 0.25 mol of potassium dichromate, 250 ml of a 26% aqueous ammonia solution and 1 mol of 1-diazo-2-naphthol-6 are mixed. -nitro-4-sulfoacids. The reaction mixture was heated under reflux at 80 ^U C for 4-5 hours until the starting components have reacted to quantitatively metal complex dyes CIMordant Black 11. The reaction mixture after this time dried in the spray drier and used for dyeing wool or polyamide textile materials.

Example 3

A mixture of 1 mole of 1-phenyl-3-methyl-5-pyrazolone together with 1 mole of 1-diazo-2-naphthol-4-3-sulfoacid is dissolved in 1.8 ml of sodium hydroxide solution and 270 ml of a 26% aqueous ammonia solution. water. 0.5 mol of sodium chromate was added to the reaction mixture and the reaction mixture was heated at 80-85 ° C for 5-6 hours. At the end of this time, a red wool and a polyamide staining 2: 1 metal complex dye are obtained,

- 4 and pH value

236 118 of the reaction mixture is isolated by filtration after acidification to = 3 to 5.

Claims (2)

A one-step process for preparing symmetrical metal-complex azo dyes from the group consisting of dyes of formulas I and II & characterized in that the starting diazotization and coupling components allow the hexavalent egg to react in the pritone. The chromium (III) oxide, optionally in admixture with the chromium ions, is at a concentration corresponding to the stoichiometric ratio or using an excess thereof at a temperature of 25 to 100 ° C. 2. A process according to claim 1, characterized in that the chemical reaction of the starting components is carried out in a neutral to alkaline reaction medium in the range of pH 6 to 12, preferably containing ammonium ions.