CH298139A - Process for the preparation of a disazo dye. - Google Patents

Description

  

  Process for the preparation of a disazo dye. It has been found that a valuable disazolar material is obtained by using the aminoinonoazo dyes of the formulas
EMI0001.0005
    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 lightfastness. After the one or two bath re-coppering process, greenish yellow shades of high purity and very good wet and light fastness are obtained.



  The combination of the two amino monoazo dyes to form the asymmetric urea derivative by means of phosgene is expediently carried out in an aqueous, weakly alkaline, e.g.

   B. alkali carbonate alkaline medium at a slightly elevated temperature in the presence of a buffer substance such as sodium acetate. The pH value favorable for the reaction is between 9.5 and 5.5. <I> Example: </I> <B> 17.25 </B> parts of 1-amino-2-chloro-4-nitrobenzene are diazotized in a known manner and <B> 13.8 </B> parts 1 -Oxybenzene-2-carboxylic acid in weakly acidic to alkaline solution gekup pelt.



  32.15 parts of the separated and dried dye are added to 120 parts of fuming sulfuric acid with a free anhydride content of 20% and for 10 hours with thorough stirring Heated <B> 95 </B> to 10011. After cooling, the reaction mass is poured onto ice, stirred for a few hours and filtered. The dye paste is dissolved in <B> 350 </B> parts of hot water and filtered, with a small part of the unsulfonated dye remaining on the filter.

    <B> 30 </B>% sodium hydroxide solution is added to the filtrate until an alkaline reaction to brilliant yellow occurs and the sodium salt of the dye precipitates with sodium chloride.



  The paraffin paste is dissolved in <B> 500 </B> parts of water and the nitro group is converted into the amino group with <B> 9.2 </B> parts of sodium sulphate at <B> 60 </B> to 7011, the aminoazo color The substance is separated and filtered with sodium chloride.



  <B> 16 </B> parts of anhydrous sodium carbonate are added to the dye paste dissolved in <B> 800 </B> parts of water and then <B> 26 </B> parts are left at 40 to 5011 p-Nitrobenzoyl chloride, dissolved in <B> 50 </B> parts of acetone, flow in. After the condensation has ended, the precipitated dye is filtered and the nitro group is converted into the amino group as usual with sodium sulphide at about 60 to 6511.

      49 parts of the separated and dried dye, or a corresponding amount of dye paste and <B> 37.1 </B> parts of 4-amino-2-chloro <B> - </B> 4'- oxy-1,1 ' -azobenzene-3'-earbonsäiire-5'-sulionsä-Lire are treated in a known manner in the presence of sodium carbonate as the acid-binding agent and sodium acetate as a buffer substance with phosgene until no amino group can be detected. The completely precipitated dye is filtered and dried.

 

Claims (1)

<B> PATENT CLAIM: </B> Process for the production of a disazolar material, characterized in that the aminomonoazo dyes of the formulas EMI0002.0035 united by means of phosgene to form the urea derivative. The new dye forms a yellow-brown powder which dissolves in water with a yellow color and dyes cotton and regenerated cell-lilos in bright greenish yellow tones with good wetness and lightness. After the one or two bath re-coppering process, greenish yellow shades of high purity and very good wet and light fastness are obtained. SUB-CLAIM-I: Process according to patent claim, characterized in that the treatment with phosgene is carried out in an aqueous medium at a pH between <B> 9.5 </B> and <B> 5.5 </ B> lies.