CH146777A - Process for the preparation of an etch-resistant dye of the gallocyanin series. - Google Patents

Description

  

  Process for the preparation of an etch-resistant dye of the Gallocyaninreilie. The main patent relates to a process for the production of a new dye of the gallocyanin series, which is characterized in that the dye obtainable from gallamide and nitrosodiethyl meta-toluidine condenses with diethyl par-a-pilenylenediamine under the simultaneous action of oxidizing agents becomes.



  The new dye will likely match the following formula:
EMI0001.0011
    At the point marked x - in the meta position to the diethylamino group - it bears a substituent (CHs). Compared with the corresponding known dye which has no substituent at the point indicated, the new meta-substituted dye proves to be much more resistant to reducing agents. It is therefore particularly suitable for use in low-pressure etching printing.



  It has now been found that a similar, also etch-resistant gallocyanine dye is obtained if the corresponding one of gallamide and nitrosodimethyl-meta-toluidiri is used in the process of the main patent in place of the dye mentioned and this under the simultaneous action of oxidizing agents with diethyl Paraphenylenediamine is condensed.



  The process is illustrated by the following example: 35 parts of the dye from gallamide and nitrosodimethyl-meta-toluidine are heated to 70 ° C. for 3 hours with 100 parts of diethyl-para-phenylenediamine and 10 parts of dinitrobenzene. plan then adds 300 parts of alcohol while stirring, lets it cool down completely and then filters, presses and dries. The condensation product is obtained in the form of a greenish crystalline powder. The same dissolves in concentrated sulfuric acid with a red color, which turns red-violet when diluted with water.

   As a hydrochloric acid, the new body dissolves with a blue color, which turns red-violet when excess hydrochloric acid is added. The color base can be precipitated from this solution with sodium acetate solution in the form of blue flakes.



  The dye is advantageously used for dyeing and printing in the form of its leuco compound. In chrome printing, it delivers navy blue tones that are more reddish than those of the product of the main patent. Thanks to its resistance to reducing agents, it is suitable for use in reduction color etching printing.



  The process can also be carried out in such a way that, in accordance with the procedure of Swiss Patent No. 70867, the starting dye mentioned in the example is stirred with the diamine oil at ordinary temperature for many hours, with the oxygen in place of the dinitrobenzene Air is responsible for the reoxidation of the leuco compound of the starting dye which occurs in the reaction mass.

 

Claims (1)

PATENT CLAIM: Process for the preparation of a new dye of the gallocyanin series, characterized in that the dye obtainable from gallamide and nitrosodimethyl-meta-toluidine is condensed with diethyl-para-phenylenediamine with the simultaneous action of oxidizing agents. The new condensation product, a greenish crystalline powder; dissolves in concentrated sulfuric acid with a red color, which turns red-violet when diluted with water. The new body dissolves as a chlorine hydrate with a blue color, which turns red-violet when excess hydrochloric acid is added. The color base can be precipitated in the form of blue flakes with sodium acetate solution from this solution. The dye is advantageously used for dyeing and printing in the form of its leuco compound. In chrome printing, it delivers navy blue tones, more reddish than those of the product of the main patent. Thanks to its resistance to reducing agents, it is suitable for use in reduction color etch printing.