DE33088C - Process for the preparation of benzidine sulfone and sulfonic acids and azo dyes therefrom - Google Patents

Description

IMPERIAL

PATENT OFFICE.

As in DRP No. 27954 has been described, obtained by heating benzidine with fuming sulfuric acid at temperatures over 170 ⁰ C. four different new sulphonic acids whose changing amount is due to the temperature and duration of exposure by the strength of the acid, height.

I. We have now found, that during the heating of benzidine or its salts with fuming sulfuric acid at temperatures below 120 ⁰ C. gröfster with ease a new substance, benzidine, is formed which is then further by heating with sulfuric acid to temperatures above 120 ⁰ C. completely converted into its sulfonic acids.

The best way to proceed is as follows: Partly free benzidine or one of its salts becomes three to four times the amount of fuming sulfuric acid of 40 pCt. Anhydride content slowly added and heated in a water bath at 100 ° C for as long, usually 1 hour, until all the benzidine has disappeared and a sample of the melt after the addition with sodium hydroxide solution from its filtrate no benzidine in the characteristic, shiny silver Lets the leaflets crystallize out more. The melt is then poured into water and then separated about 24 hours of standing the separated sulfuric acid benzidine sulfone from the excess Sulfuric acid by filtration. About the same of any small amounts of unchanged benzidine or with resulting To separate sulfonic acids, the gray-white residue is boiled with sodium hydroxide solution and obtained so in an almost quantitative amount a yellow substance which, filtered off, in hot, dilute hydrochloric acid dissolved and filtered again, with sodium hydroxide solution as a perfectly pure yellow, amorphous one Precipitation precipitates.

Time, temperature and strength of the complement each other in the formation of this substance Acid each other. Instead of the fuming acidity of 40 pCt. Anhydride content can be weaker or even stronger acids, free anhydride or monochlorohydrin according to the time use. In all cases, the formation of the benzidine sulfone can easily be demonstrated. Even when entering benzidine the greater part of it becomes in fuming sulfuric acid at ordinary temperature converted to sulfone.

Benzidine sulfone on the composition

; H ₃ NH ₂

C ₆ H ₃ NH ₂

SO ₀

is a yellow, amorphous substance which, in cold but is difficult in hot water insoluble and only melts above 300 ⁰ C. with decomposition. It has weakly basic properties and forms salts with acids, of which the sulfuric acid salt, unlike the sulfuric acid benzidine, dissolves easily in hot, acidic water and, when cooled, crystallizes in beautiful, long, silky-shiny needles. This dissolves in concentrated or fuming sulfuric acid

Sulphone easily and changes into its sulphonic acids when heated to temperatures above 120 ^{° C.} However, if the temperature exceeds (150 to 160 ⁰ C), then the sulfone began under sulfurous acid - to decompose development, and form the Benzidinsulfosäuren.

II. The method for the rational preparation of the sulfonic acids of benzidine sulfone results from this last property. Depending on whether one wants to represent the mono- or Disulfosä'ure of Benzidinsulfons, must, to the sulfone shown in the above manner shorter or longer period with fuming sulfuric acids at temperatures of between 120 and 160 ⁰ C. heat. (However, in order to achieve good yields, the temperature must not exceed 160 ° C.)

In order to obtain the most valuable of the two, benzidine sulfone disulfonic acid, in a process without isolation of the free sulfone, we proceed as follows: Partly free benzidine or, most simply, sulfuric acid benzidine with 4 parts fuming sulfuric acid of 40 pCt. Anhydride, as increase in the representation of the sulfone, in a closed vessel, for 1 hour at ioo ° C heat, on the temperature to 150 ⁰ C and hold here until everything sulfone gone up and the Sulfondisulfosäure is formed, namely, until a sample of the product of action dissolves easily in hot water and no more yellow precipitate is formed on the addition of bases. The melt is then poured into water, the benzidinesulfondisulfonic acid which separates out is filtered off and it is purified according to the method specified in DRP No. 27954 under III. described method. We get around 80 pct. of the applied sulfuric acid benzidine to benzidinesulfondisulfonic acid.

III. Just like the Benzidinsulfonmono- and Benzidinsulfondisulfoäure, as already in the D. R. P. No. 27954 described under V., C. and D., also forms the benzidine sulfone in its tetrazo compound with phenols, amides and their sulfonic acids dyes, which are truer and more bluish than that of benzidine.

You get:

ι. red dyes by combining with phenol, resorcinol, α- and ß-naphthol and their Sulfonic acids;

2. violet, water-insoluble, but fuel-soluble dyes by combining with a- and ß-naphthylamine;

3. blue-violet, water-soluble dyes by combining with the sulfonic acids of a- and ß-naphthylamine;

4. yellow dyes by combining with aniline, toluidine, xylidine and its sulfonic acids, as well as with salicylic acid.

As for the representation of these dyes, they are created with use equivalent proportions according to the generally known methods.

As an example we give the following:
10 kg of benzidine sulfone are dissolved in hot, dilute hydrochloric acid and the cooled solution is diazotized with a solution of 5.6 kg of nitrous acid sodium in 12 kg of water. The diazo compound thus obtained is then added to 18 kg of naphthoic acid suspended in water, and so much acetic acid sodium is added until the dye has formed completely.

. A dye is obtained in this way, which unheated cottons in a boiling soap bath colors blue-violet.

Claims (4)

Patent claims: ι. The procedure of. Production of benzidine sulfone by the action of two or more times the amount of fuming sulfuric acid or an analogous amount of sulfuric acid anhydride or monochlorohydrin at temperatures below 120 ^° C. on benzidine. 2. The process of converting the benzidine sulfone to the benzidine sulfone monobezw. Benzidine sulfone disulfonic acid by heating it with fuming sulfuric acid to temperatures above 120 ^° C. 3. The method of direct representation of the sulphonic acids, especially the disulfonic acid of Benzidinsulfons, first to DAF at temperatures below 120 ⁰ C. for the purpose of the temporary representation of the sulfone heated by Sulfirung of benzidine in the way, then the temperature is above 120 ⁰ C. , but not above 160 ⁰ C. increases. 4. The process of preparing new dyes by combining the benzidine sulfone in the form of its tetrazo compound with those mentioned under III., 1. to 4. Amides, phenols and their sulfonic acids.