CH289990A - Process for the preparation of a new monoazo dye. - Google Patents

Description

  

  Process for the preparation of a new monoazo dye. It has been found that a new valuable monoazo dye is obtained if 1-n-octyl-3-methyl-5-pyrazolone is coupled with diazotized 1-amino-2-oxynaphthalene-4-sulfonic acid. The new dye dissolves in water with red, in dilute sodium hydroxide solution with orange and in concentrated sulfuric acid with violet color;

   it dyes wool from an acetic acid bath in orange tones, which are converted into a red with good fastness properties when they are chromed.



  The 1-n-ethyl-3-methyl-5-pyrazolone of the formula used as starting material here
EMI0001.0014
    can by reacting the monooctyjhydrazine with acetoacetic acid amide or an acetoacetic acid ester, e.g. the methyl or ethyl ester. The hydrazine required for this in the composition
EMI0001.0023
    can be produced by reacting hydrazine with n-octyl halides (e.g.

   B. n-Oetylchlorid).



  The preparation of the monooctylhydrazine is conveniently carried out by converting hydrazine sulfate into hydrazine hydrate in ethyl alcohol using an alkali metal hydroxide and heating a considerable excess of the hydrazine hydrate thus dissolved with the n-octyl halide for a long time and then reacting it with sulfuric acid.

   Since the resulting monooctylhydrazine sulfate is much more readily soluble in alcohol than the excess hydrazine sulfate, separation is easily possible and a monooctylhydrazine sulfate which is sufficiently pure for further processing can easily be isolated from the reaction mixture.



  This can then in known, z. B. for the preparation of 1-aryl-3-methyl-5-pyrazolonen conventional method with acetoacetamide or ethyl acetoacetate by means of acid-binding agents - in the first case expediently with the addition of acetic acid and alkali acetate, in the second case with the addition of alkali hydroxide - for 1-n-octyl-3-methyl-5-pyrazolone condensed who the.



  The coupling of the diazotized 1-amino-2-oxynaphthalene-4-sulfonic acid with the 1-n-octyl-3-methyl-5-pyrazolone can take place, for example, in a weakly acidic to weakly alkaline medium.

        <I> Example: </I> 23.9 parts of 1-amino-2-oxynaphthalene-4-sulphonic acid are diazotized in the usual way, and the diazo compound is poured into a cooled solution of 21.0 parts of 1-n- Octyl-3-methyl-5-pyrazolone, 4 parts of sodium hydroxide and 5.3 parts of anhydrous sodium carbonate in 350 parts of water. After coupling has been completed, the precipitated dye is filtered off, washed with dilute sodium chloride solution and dried.



  The 1-n-octyl-3-methyl-5-pyrazolone used here can be made, for example, as follows: 210 parts of 98% sodium hydroxide are dissolved in 700 parts of ethyl alcohol and 168 parts of about 991% hydrazine sulfate are dissolved in 40 twice with stirring admitted.

    After 30 minutes, 100 parts of 98% sodium hydroxide and 168 parts of hydrazine sulfate and then a further 95 parts of 98% sodium hydroxide and 168 parts of hydrazine sulfate are added in the same way.

   The easily stirrable mass obtained in this way is stirred cold overnight and the sodium sulfate formed is filtered off with suction; this is washed with 200 parts of ethyl alcohol, the filtrate is combined with the 'VV ash alcohol and made up to 1000 parts by volume with alcohol.



  The solution thus obtained is refluxed with 148.5 parts of n-octyl bromide (about 1 mol to 5 mol of hydrazine) with thorough stirring for 18 hours and allowed to cool. At 10 to 20, 500 parts of 98% strength sulfuric acid (5 mol) are slowly run in with thorough stirring, and the mixture is then stirred for 1 hour.

   Most of the n-octyl hydrazine sulfate formed precipitates with the hydrazine sulfate. The n-oetylhydrazine sulfate can be easily separated from the hydrazine sulfate by boiling off with ethyl alcohol and allowed to crystallize from the resulting solution. After filtering and drying, white flakes are obtained which melt at 146 to 147.



  48.4 parts of the n-octylhydrazine sulfate thus obtained are stirred in 480 parts of water from 30 to 40 and 55 parts of crystallized sodium acetate and 5 parts of glacial acetic acid are added. 20.2 parts of acetoacetic acid amide (obtainable in accordance with Example 7 of American Patent No. 2152132) are added and the mixture is stirred for a few hours at room temperature. The pyrazolone formed falls. slowly out. It is filtered, washed with water and dried at 50 in vacuo. It forms a light brown powder.

   Recrystallized from alcohol, the 1-n-octyl-3-methyl-5-pyrazolone melts at 59 to 60.

 

Claims (1)

PATENT CLAIM: Process for the preparation of a new monoazo dye, characterized in that 1-n-octyl-3-methyl-5-pyrazolone with. diazotized 1-amino-2-oxynaphthalene-4-sulphonic acid couples. The new dye dissolves in water with red, in dilute sodium hydroxide solution with orange and in concentrated sulfuric acid with purple color; He dyes wool from acetic acid baths in orange tones, which are transformed into a red with good fastness properties when re-enumerating.