CH210507A - Process for the preparation of a chromable dye of the triarylmethane series. - Google Patents

Description

  

      Additional patent to main patent No. 198713. Process for the production of an honorable dye of the triarylmethane series The subject of this additional patent is a process for the adjustment of a chromable dye of the triarylmethane series, which is characterized by

   that 1 mol of 5-oxytrimellitic anhydride is condensed with 2 mol of resorcinol and the dye thus obtained is brominated until 4 bromine atoms enter.



       Examples: 1. 21 parts by weight of 5-oxytrimellitic anhydride and 22 parts by weight of resorcinol are finely ground and melted. 7 parts by weight of de-aqueous zinc chloride are stirred into the melt and the mixture is heated to 180-190 ° C. for 4-5 hours. During this time, the melt solidifies.

   After cooling, it is finely pulverized and digested with 100 parts by weight of about 5% hydrochloric acid in the warm for a long time. The yellow residue is filtered off with suction while warm, dissolved in soda solution, the solution is filtered and the yellow dye is precipitated from the orange-red solution with dilute hydrochloric acid. The dye can be redissolved from aqueous alcohol for further purification. The easily soluble orange-red sodium salt is obtained by dissolving the required amount of sodium bicarbonate in water and evaporating.



  39 parts by weight of the dye obtained in this way are suspended in 200 parts by weight of glacial acetic acid and a solution of 68 parts by weight of bromine in 100 parts by weight of glacial acetic acid is added dropwise with stirring. When the bromine is used up, the orange-yellow dye is sucked off, washed with a little ice vinegar and then with a lot of water Congo-neutral. The dye can be recrystallized from a lot of hot glacial acetic acid or aqueous alcohol.

   The dye probably has the following constitution:
EMI0002.0001
    or is an isomer thereof or a mixture of the isomers.



  The dye dyes wool from an acid bath in very clear, yellowish red shades and the fastness properties are significantly improved by post-chrome plating. The dye is particularly suitable for chrome printing on cotton and rayon.



  2. If 1 mole of 5-oxytrimellitic anhydride is condensed with only 1 mole of resorcinol at a lower temperature than that described in Example 1, namely one at which no significant dye formation takes place, 1- (2 '. 4'-Dioxybenzoyl) - o-oxycarboxy-2-benzoic acid, probably of the following constitution:

    
EMI0002.0014
    32 parts by weight of the benzoylbenzoic acid thus obtained are melted with 20 parts by weight of resorein at 180 ° C. for 4-5 hours. After cooling, the yellow melt is pulverized and dissolved in dilute sodium hydroxide solution. The solution is heated to the boil and acidified with dilute hydrochloric acid. After cooling, the yellow precipitate is filtered off with suction, washed neutral and dried.

   If necessary, the dye can be dissolved in aqueous alcohol. The easily soluble sodium salt is obtained by dissolving in dilute alkalis and evaporating the solution.



  The dye thus obtained, which is identical to the dye obtained in the first paragraph of Example 1, is brominated as described in Example 1 to give the tetrabromo dye.

 

Claims (1)

Claim: Process for the production of a chromable dye of the triarylmethane series, characterized in that 1 mole of 5-oxytrimellitic anhydride is condensed with 2 moles of resorcinol and the dye thus obtained is brominated until 4 bromine atoms enter. The dye obtained in this way dyes wool from an acid bath in very clear yellowish red shades and the fastness properties are significantly improved by re-chroming. The dye is suitable. particularly good in chrome printing on cotton and rayon. SUBSTANTIAL CLAIM: Process according to patent claim, characterized in that the bromination is effected with bromine in the presence of glacial acetic acid at room temperature.