CH302046A - Process for the preparation of a disazo dye. - Google Patents

Description

  

  <B> Additional patent </B> to main patent no. 298139. Process for the production of a disazo dye. It has been found that a useful disazo dye is obtained by using the amino monoazo dyes of the formulas
EMI0001.0006
    united by means of phosgene to form the urea derivative.



  The new dye forms a yellow-brown powder that dissolves in water with a yellow color and dyes cotton and regenerated cellulose in bright greenish yellow shades of good wet and lightfastness. After your one or two bath re-coppering process, you get greenish yellow shades of high purity and very good wet and light fastness.



  The combination of the two Aminomono t zofarrebs to the asymmetric urea derivative by means of phosgene is expediently carried out in aqueous, weakly alkaline, eg B. alkaline carbonate alkaline medium at a slightly elevated temperature in the presence of a Buf fersubstanz such as sodium acetate. The pa value, which is favorable for the reaction, is between 9.5 and 5.5.



       Example: 17.25 parts of 1-amino-2-chloro-4-nitrobenzene are diazotized in a known manner and kup pelt with 13.8 parts of 1-oxybenzene-2-carboxylic acid in weakly acidic to alkaline solution.



  32.15 parts of the deposited and dried dyestuff are added to 120 parts of fuming sulfuric acid with a free anhydride content of 20% and heated to 95 to 100 hours with thorough stirring. After cooling, the reaction mass is poured onto ice, stirred for a few hours and filtered. The dye paste is dissolved in 350 parts of hot water and filtered, a small amount of unsilfonized dye remaining on the filter.

   The filtrate is treated with 30,010 iger sodium hydroxide solution until an alkaline reaction to brilliant yellow occurs and the sodium salt of the dye is precipitated with sodium chloride.



  The dye paste is dissolved in 500 parts of water and the nitro group is converted into the amino group with 9.2 parts of sodium sulfate at 60 to 100, the aminoazo dye is deposited with sodium chloride and filtered.



  16 parts of anhydrous sodium carbonate are added to the dye paste dissolved in 800 parts of water and 26 parts of m-nitrobenzene chloride dissolved in 50 parts of acetone are then allowed to flow in at 10 to 50 parts. After the condensation has ended, the dyestuff which has precipitated out is filtered and the nitro group is converted into the amino group as usual with sodium sulfide at about 60 to 65.



       4-9 parts of the separated and getrock designated dye or a corresponding amount of dye paste and 37.1 parts of 4- amino-2-eh @ or - @ -'-ov-1,1'-azobenzene-3'-carboxylic acid-5 '- sulfonic acid are treated with phosgene in a known manner in the presence of sodium carbonate as an acid-binding agent and sodium acetate as a buffer substance,

   until no more amino groups can be detected. The completely precipitated dye is filtered and dried.

 

Claims (1)

PATEN TAN SPRICH Process for the preparation of a disazo dye, characterized in that the aminomonoazo dyes of the formulas EMI0002.0049 united by means of phosgene to form the urea derivative. The new dye forms a yellow-brown powder that dissolves in water with a yellow color and dyes cotton and regenerated cellulose in bright greenish yellow tones with good wet and light fastness. After the one or two bath re-coppering process, greenish yellow shades of high purity and very good wet and light fastness are obtained. SUBCLAIM: A method according to the patent claim, characterized in that the treatment with phosgene is carried out in an aqueous medium at a pH between 9.5 and 5.5.