CH183456A - Process for the preparation of a new trisazo dye. - Google Patents

Description

  

  Process for the preparation of a new trisazo dye. According to the present invention, a new trisazo dye for leather is produced by coupling resorcinol with a diazotized mixture of 3- and 5-amino salicylic acid,

   lets diazotized 6-chloro-2-aminophenol-4-sulfonic acid act on the monoazo dye thus obtained and brings diazotized p-nitroaniline into effect on the disazo dye, all couplings taking place in an aqueous, alkaline leadium.



  The new dye is a brownish black powder, which easily dissolves in water to form a yellow-brown solution. The aqueous solution becomes more yellow after the addition of hydrochloric acid and redder after the addition of caustic soda. The new dye dissolves in concentrated sulfuric acid to form a red-brown solution, which becomes more yellow after dilution with water.



  The new dye dyes and stains vegetabili, 3ch and chrome-tanned leather in even brown tones that are good lightfastness and washfastness.



       Example: An aqueous suspension of the diazo compound, which was prepared in the usual way from 15.3 parts of a mixture of 3- and 5-amino-salicylic acid, is stirred into a solution of 11 parts of resor- cin in 175 parts of a ten percent wäs serigen caustic soda solution at 10 C was added. The coupling takes place fairly quickly and is complete in 2-3 hours,

      during which time the reaction mixture on lacquer remains alkaline. The diazo solution obtained from 22.35 parts of 6-chloro-2-aminophenol-4-sulfonic acid with 6.9 parts of solid sodium nitrite and 90 parts of a ten percent aqueous hydrochloric acid is then added to the solution of the monoazo compound, whereupon, if necessary, a further addition of caustic soda solution can follow to keep the mixture alkaline, and the mixture is stirred at room temperature to

   until the formation of the disazo dye is complete. The coupling solution is then by adding. Ice cooled to below 10 ° C, and the diazo solution made up of 1.6.8 parts of p-nitroaniline is stirred in.

   A sufficient quantity of ten percent aqueous caustic is slowly added to the mixture until the reaction mixture reacts alkaline to litmus; then you can recouple for 12 hours. The new dye is then salted out after adding hydrochloric acid to acidify the reaction mixture to litmus. It dyes leather in vegetable and chrome tanning in exceptionally even tones with good strength properties.

 

Claims (1)

PATENT CLAIM: Process for the production of a new trisazo dye, characterized in that resorcinol is coupled with a diazotized mixture of 3- and 5-aminosalicylic acid, lets diazotized 6-chloro-2-aminophenol-4-sulfonic acid act on the monoazo dye thus obtained and brings diazotized p-nitroaniline into effect on the disazo dye, all couplings taking place in an aqueous, alkaline medium. The new dye is a brownish black powder, which easily dissolves in water to form a yellow-brown solution. The aqueous solution becomes more yellow after the addition of hydrochloric acid and redder after the addition of caustic soda. The new dye dissolves in concentrated sulfuric acid to form a red-brown solution, which becomes more yellow after dilution with water. It dyes and stains vegetable and chrome-tanned leather in uniform brown tones with good lightfastness and wash resistance.