DE589636C - Process for the production of azo dyes - Google Patents

Description

Process for the production of azo dyes New valuable, especially Acid dyes suitable for dyeing leather are hooked if 1, 3-Dioxybenzol or its carboxylic acids with one mole of 2-nitro-i-amino-4.-diazobenzene and one mole of the - the same or a different diazo or a diazoazover bond couples. These Depending on the choice of components, new azo dyes give leather different shades of brown.

Against similar dyes that are different from the above-mentioned distinguish that. i-nitro-4-diazobenzene is assumed, with the following Reduction, the nitro group is reduced to the amino group, have the invention available dyes have the advantage of a nicer, less reddish shade, which is desirable when dyeing leather. Furthermore, the new dyes do not tend for bronzing, if they are dyed on leather that has not been deacidified, and have them a better fastness to alkalis.

EXAMPLE 19 parts of 2-nitro-1,4-diamnobenzene hydrochloric acid are dissolved with 23 parts of formic acid in 250 parts of water and dianotized at 0 ° C. with 6.9 parts of sodium nitrite. This solution runs at 0 ° C. to a solution of 15.4 parts of 1,3-dioxybenzene-5-carboxylic acid, 50 parts of sodium bicarbonate and 100 parts of salt in 300 parts of water. After the coupling has ended, the dye is filtered off with suction and again dissolved in 22 parts of sodium carbonate in 1,000 parts of water. For this purpose ° runs at io ° C a solution of 8.6 parts of 1 dianotierter i-amino-4-nitrobenzene-2-sulphonic acid. After 1 hour the solution is heated to 70 ° and the dye is isolated and dried. It is a dark green powder that is soluble in water with a reddish brown color, in concentrated sulfuric acid with a red color, and gives leather a strong reddish brown color. Example 2 Replacing the i-amino-4-nitrobenzene-2-sulfonic acid in Example i with 27.7 parts of 4-aminoazobenzene-4'-sulfonic acid results in a dye which is red-brown in water and violet in color is soluble in concentrated sulfuric acid and dyes leather in a redder shade than the dye obtainable according to Example i.

Example 3.

48.4 parts of the dye from dianotated i-amino-8-oxynaphthalene-3, 6-disulfonic acid and 1; 3-Dioxybenzene is dissolved in 1,000 parts of water and 47 parts 3% sodium hydroxide solution dissolved. 38 parts of hydrochloric acid 2-nitroi, 4-diaminobenzene with 58 parts of 32 percent hydrochloric acid in 500 parts of water solved and dianotized at 0 ° C with 13.8 parts of sodium nitrite. This solution runs at i5 ° C simultaneously with 100 parts of 14% sodium hydroxide solution to the solution of the monoazo dye. After: several hours, the dye is salted out and suctioned off. After drying is it a dark powder; soluble in water with reddish brown ,. in more concentrated Sulfuric acid with a gray-green color. The dye turns leather gray-brown.

If, instead of 38 parts, 2-nitro-1, q.-diaminobenzene 19 Parts in use result in a dye with similar properties. He colors leather in a slightly redder shade.

Example q.

A diazo compound prepared according to Example 1 from 38 parts of hydrochloric acid 2-V itroi, q.-diaminobenzene is left with cooling in an alkaline solution of i i parts of i, 3-dioxybenzene run in, the coupling mixture being run through simultaneous addition of caustic soda until the end receives alkaline soda. Of the After the reaction has ended, dye is deposited in a known manner. Created after drying it is a dark powder and dyes leather yellow-brown.

Claims (1)

PATENT CLAIM: Process for the production of azo dyes, thereby characterized in that i, 3-Dioxybenzol or an i, 3-Dioxybenzolcarbonsäuze with 1 mole of 2-nitroamino-q.-diazobenzene and i mole of the same or a different diazo or a diazoazo compound couples.