DE79029C - Process for the preparation of a monoazo dye from ai a ^ -Dioxynaphthalene disulfonic acid G. - Google Patents

Description

IMPERIAL

PATENT OFFICE / V ^

A series of azo dyes is described in patent specifications No. 51559 and No. 52958, as well as patent specifications No. 52140 and No. 53499, which are derived from Ct ₁ Ct ₄ (1 · S) -dioxynaphthalene; It has been pointed out that this dioxynaphthalene, which distinguishes itself from all other isomers, is of great value for paint technology. On further pursuit of this direction it has now been shown that the action of concentrated sulfuric acid on this dioxynaphthalene in addition to other sulfonic acids, some of which are worthless for paint technology, gives rise to a new disulfonic acid in which the excellent action of the peri-positioned hydroxyl groups is again exerted in an excellent manner. Thus, the dye produced by the action of diazobenzene chloride on this disulfonic acid shows an eminent crystallization power and, with completely satisfactory lightfastness, a very extraordinary purity of the color shade. This behavior is in complete contrast to the observations recorded in patent specification No. 54116, because according to this, "all dioxynaphthalene sulfonic acids which are obtained by further sulfurizing dioxynaphthalene produce very light-inadequate worthless dyes". The preparation of the new disulfonic acid and its separation from other sulfonic acids can be done in the following way:

10 kg U ₁ a _i - Dioxynaphtalin are dissolved at 10 to ι 5 ⁰ C. in 40 kg of sulfuric acid of 66 ⁰ B.. After the dioxynaphthalene has been entered, the mixture is ^{heated to 50 °} C. for 45 to 50 minutes, respectively. until a sample is clearly soluble in water. It is then added to 200 liters of ice water and neutralized with saturated barythydrate solution. After boiling, it is filtered and the barium sulphate is washed out with boiling water. The combined filtrates, which may show only a weak alkaline reaction, are evaporated to about 250 liters. When the liquid cools, a barium salt separates out, which is filtered off and washed out with a little cold water. This barium salt is sparingly soluble even in hot water (barium salt I) and contains a Ct ₁ ct ₄ -dioxynaphthalene sulfonic acid which is worthless for the preparation of the dye. The mother liquor filtered off from the barium salt I is further evaporated to about 40 liters; When it cools down, a second barium salt separates out, which, in contrast to the one that was crystallized out first, is easily soluble in hot water (barium salt II) and contains a Ci ₁ c ^ -dioxynaphthalene disulfonic acid which is valuable for paint technology and which, when combined with diazobenzene, also contains acetic acid, than forms a red wool dye in an alkaline solution.

By dissolving the barium salts in boiling water and reacting them the corresponding sodium salts can be obtained with soda or Glauber's salt.

In the following, the acid corresponding to the barium salt II is referred to as Ct ₁ a ₄ - dioxynaphthalene disulfonic acid G. This sulfonic acid is new and differs from the previously known and used for the preparation of azo dyes by the reactions given in the table below.

Tabular overview of the a _x c ^ -Dioxynaphthalene disulfonic acids. (Solution of the sodium salts ι: 200.)

Ferric chloride Ferric chloride in
larger quantities Chlorinated lime Chlorinated lime in
larger quantities Dioxynaphthalene disulfonic acid
. (Patent No. 57021) yellow-green blue green yellowish yellow-red.
Precipitation Dioxynaphthalene disulfonic acid
(Patent No. 69095) green yellow-brown red yellow,
Precipitation Dioxynaphthalene disulfonic acid G.
present patent specification green dirty green Brown brownish red,
Precipitation.

Example for the representation of the wool dye:

By reacting the barium salt II with Glauber's salt, a solution of the sodium salt of α, α ₄ -dioxynaphthalene disulphonic acid G is prepared, the content of which is determined by titration with diazobenzene in acetic acid solution using a known method, and this solution is adjusted to a content of 20 pCt. free dioxynaphthalene disulfonic acid. 160 kg of this solution, which corresponds to 32 kg of dioxynaphthalene disulphonic acid, are mixed with 35 kg of crystallized sodium acetic acid; in this solution at läfst io ° C. with constant stirring, of 9.3 kg of aniline, 20 1 water and 40 kg of hydrochloric acid (3opCt. Cl H containing) prepared in known manner with addition of 50 kg of ice and 7 kg of sodium nitrite solution run in respectively from diazobenzene chloride. so much diazobenzene chloride until a sample of the dye solution precipitated with common salt on filter paper shows only a faint red color in the leaking edge when dabbed with the diazo compound.

After a short time, the deep red dye solution begins to excrete more shiny red needle, which is completed after a few hours; it is filtered and the residue is prefilled and dries.

If the dye formation is allowed to take place in a more dilute solution, it separates Dye does not or only imperfectly. In this case the same can be used in crystallized form by boiling and adding common salt until a sample is obtained shows almost complete excretion of the dye on cooling. After cooling down is then worked up as indicated above.

If the dyestuff preparation is to be carried out in an alkaline solution, it is replaced The amount of sodium acetic acid given in the above procedure by 14 kg of calcined soda.

An excess of diazo compound is particularly careful when using soda Avoid, as it gives rise to the formation of an impure dye.

The alkaline solution becomes the dye precipitated with table salt and worked up as usual.

The dye thus obtained, which when dried is a reddish brown powder represents, dyes wool in an acidic bath bluish-red.

Claims (1)

Patent claim: Process for the preparation of a red dye wool, consisting in one of the resulting That the Baryuiiisalze by the action of concentrated sulfuric acid at H ₁ a ₄ -Dioxynaphtalin at 50 ⁰ C. Dioxynaphtalinsulfosäuren in a sparingly soluble in hot water and in a slightly ■ in hot water soluble , separates crystallizing salt on cooling and combines the Ci ₁ a ₄ -dioxynaphthalene disulphonic acid corresponding to the latter with diazobenzene in an acetic or alkaline solution.