DE313523C - - Google Patents

Description

It has been found that new bodies are obtained with valuable tanning properties if one uses the salts of aminooxynaphthalene sulfonic acids in aqueous solution Brings formaldehyde together at normal temperature, if necessary with the addition of acid, and about in the ratio of 2 mol. Sulphonic acid to ι mol. Formaldehyde.

From the procedure of the British patent " font 4648/1911 differs from the present one Process due to the complete absence of concentrated sulfuric acid in the Condensation. This eliminates the possibility that as with the known Process sulfur in some form enters the molecule of the new compounds.

The procedure of the patent specification. 179020,

Class 22 b, relates only to the condensation of i-aminonaphthalene or. i-oxynaphthalene-3-sulfonic acid or their derivatives with formaldehyde. In part, different from the present one Process condensed in alkaline solution. But there are also significant differences where the formaldehyde has an effect on the solution of the acid itself compared to the present proceedings. So z. B. consistently with a lot of formaldehyde condenses at a higher temperature, which is reflected in the reactivity of the formaldehyde of is of particular importance, and, as is expressly emphasized in the patent specification, further transformations and changes, such as splitting off of sulphurous acid etc. entails. . - -35

From the patent specification 88434, class 12, is also known a method according to welc.hem methylene-2-amino-8-oxynaphthalene-6-sulsäure by treating the free 2-amino-8-oxynaphthalene - 6 - sulphonic acid with formaldehyde

It is particularly emphasized in the patent that only an excess of Formaldehyde leads to the goal. So when working at normal temperature, the 5-bis 8 times the amount of theory required. Even when working at a higher temperature

- "will be more than 3 times the amount of theory used.

It is now an essential feature of the present process, that when the approximately theoretical amount of formaldehyde, the salts of the various Acids and subsequent acidification already at ordinary temperature are quantitatively the new ones Receives condensation products.

This difference occurs in a comparison experiment with the acid of patent specification 88434 clearly in appearance. If one leaves namely on the free 2-amino-8-oxynaphthalene-6-sulfonic acid at ordinary temperature the theore-. If there is a large amount of formaldehyde, it does not occur at all or only at all. very low re-

action a. However, if a salt is used instead of the free acid, e.g. B. the sodium salt, this is how the re ^ ktiörr works quantitatively. The acidification can be done later or at the same time -

early on ''-'S& gabi '-des formaldehyde happen; it is only necessary to regulate it in such a way that the precipitation of unchanged free acid is avoided.

The products manufactured according to the present process are characterized by that they have a strong glue-precipitating effect and are therefore used for tanning purposes can. Since these condensation products can also be mixed with diazo compounds to form dyes can combine the skin tanned with them by coupling with suitable diazo compounds subsequently dyed to the tanning process.

Example 1.

4.8 parts by weight of 2-amino-8-oxynaphthalene-6-sulfonic acid are replaced by 50 parts by weight , Water and 1.06 parts by weight of anhydrous sodium carbonate in solution. To the A solution of this sodium salt is added to a mixture of 12 parts by weight with stirring Acetic acid (10 percent) and 0.75 parts by weight of formaldehyde (40 percent). After short In time the condensation has proceeded quantitatively and the condensation product can pass through Precipitation can be obtained with concentrated hydrochloric acid or with sodium chloride.

In the table below are the properties of some of the following Process representable products compiled.

Condensation products from paint

with concentrated

Solubility in acetic acid I hydrochloric acid

1: 5: 7 aminooxynaphthalene sulfonic acids
1: 8: 4 aminooxynaphthalene sulfonic acids
2: 5: 7 aminooxynaphthalene sulfonic acids
2: 8: 6-amino oxynaphthalene sulfonic acids dark gray
Brown
dark red
Brown

Brown

strong yellow
Brown
brownish yellow

slightly the same. the same. the same

heavy light . difficult desgl.

Claims (1)

Patent claim:
Process for the preparation of condensation products of aminooxynaphthalene sulfonic acids and formaldehyde, consisting in allowing about 1 mole of formaldehyde in aqueous solution to act on 2 moles of a salt of an aminooxynaphthalene mono- or disulfonic acid at ordinary temperature, optionally with the addition of acid.