CH224364A - Process for the preparation of a vat dye of the naphthalimide series. - Google Patents

Description

  

  <B> Additional patent </B> to main patent no. 219657. Process for the production of an itupe dye of the naphthalimide series. The subject of this patent is a process for the production of a vat dye of the naphthalimide series, which is characterized in that 3-methoxy-naphthalmethylimide-4-thioglycolic acid of the formula
EMI0001.0011
    with an alkaline condensing agent, e.g.

   B. with a caustic potash in the presence of a liquid, aromatic or heterocyclic base, such as. B. aniline, dimethylaniline, pyridine or quinoline, in the heat, expediently at temperatures between about 80 and 200 ° C, treated and the alkali-soluble compound thus formed by treatment with an oxidizing agent, e.g.

   B. by treating the heated alkaline solution with sodium hypochlorite, potassium ferricyanide or ammonium persulfate, or by the action of air on the alkaline solution, or in ver dilute acetic acid by hydrogen superoxide, or by means of sulfuric acid, condensed to the vat dye.



  <I> Example: </I> 50 parts by weight of 3-methoxy-naphthalenemethylimide - 4 - thioglycolic acid (obtainable by reacting 3-methoxy-4-bromonaphthalimide with sodium sulphide to form the corresponding mercaptan,

      Conversion of this compound into thioglycolic acid by reaction with monochloroacetic acid and methylation of the 3-methoxynaphthalimide-4-thioglycolic acid thus obtained by treatment with methyl p-toluenesulfonate in an alkaline solution;

   crystallized from glacial vinegar in hair-thin, yellow needles with a melting point of <B> 237-239 '</B> C) are heated to 120 to <B> 130' </B> C with 200 parts by weight of powdered caustic potash in 2000 parts by weight of anhydrous pyridine at this temperature for a few hours, e.g. B. 5-6 hours, stirred. The reaction product separates out as a red-brown mass which is insoluble in pyridine. After a few hours, the residue is filtered off with suction, the red-brown residue is dissolved in water, a small amount of gray, insoluble and non-viable residue is removed by filtration and acidified with dilute hydrochloric acid.

   The condensation product separates out as a brownish precipitate; it dissolves in dilute alkalis orange-brown with yellowish-green fluorescence. Its solution color in concentrated sulfuric acid is orange.



  To convert it into the vat dye, the intermediate product is dissolved in dilute sodium hydroxide solution and dilute sodium hypochlorite solution is added to the solution at 50 to 60 ° C. until no further changes take place. The fluorescence of the solution disappears and the dye separates in blue flakes. It is filtered off, washed with hot water and dried.

   It then turns out to be a dark blue, shiny bronze powder, dissolves in concentrated sulfuric acid with an olive green color and precipitates again in blue flakes when this solution is diluted with water. With alkali and sodium hydrosulphite, the dye delivers a violet vat from which cotton is dyed in very clear blue tones. The fastness of the dyeing is good.



  The conversion into the vat dye can also take place without isolation of the intermediate product in the following way:

   The aqueous, orange-brown solution of the condensation product is acidified with acetic acid, it then takes on a red-brown color. Adding about 10 parts of a hydrogen superoxide solution results in a yellow-brown precipitate which slowly turns green-blue when heated to boiling.

    If the color no longer deepens, it is filtered off; Wash with hot water and treated with dilute, hot sodium hydroxide solution to remove alkali-soluble by-products. After repeated washing with water, the pure dye then remains as a blue residue.



  The intermediate product can also be converted into the dye by heating the deposited intermediate product at about 90-100 ° C. in 70-75% strength sulfuric acid on a water bath. The dye separates from the brown sulfuric acid solution in blue crystals and can be obtained in pure form by suction on a filter stone.

 

Claims (1)

PATENT CLAIM: Process for the production of a vat dye of the naphthalimide series, characterized in that β-methoxy-naphthalmethylimide-4-thioglycolic acid is treated with an alkaline condensing agent and the resulting alkali-soluble compound is treated with an oxidizing agent condensed to the vat dye. With alkali and hydrosulfite, the new dye provides a purple vat from which cotton is dyed in very clear blue tones. SUBClaims 1. Method according to claim, characterized in that caustic potash is used as the alkaline condensation agent. 2. Process according to the patent claim, characterized in that the alkaline condensation is carried out in the presence of a liquid, aromatic base. 3. Method according to claim. characterized in that the alkaline condensation is carried out in the presence of a liquid, heteracyclic base. 4. The method according to claim, characterized in that the alkaline condensation is carried out with caustic potash in the presence of pyridine at about 120-130 ° C. 5. Process according to patent claim, characterized in that sodium hypochlorite in a solution in dilute sodium hydroxide solution is used as the oxidizing agent for the conversion of the intermediate compound obtained by alkaline condensation into the vat dye. 6. The method according to claim, characterized in that the intermediate compound obtained by alkaline condensation is transferred into the vat dye by oxidation with hydrogen peroxide in acetic acid solution. 7th Process according to patent claim, characterized in that the intermediate compound obtained by alkaline condensation is converted into the vat dye by heating in 70 to 75% sulfuric acid at about 90-100 ° C.