CH320745A - Process for the preparation of an optical brightening agent - Google Patents

Description

  

  



  Process for the preparation of an optical brightening agent
In numerous patent documents, compounds are described which have the property of being drawn up from aqueous solution for them or in connection with detergents on textile fabrics and to give them a high degree of whiteness. A disadvantage of most of these compounds is that, with repeated use, they build up on the fabric and cause the textiles to turn gray over time.



   It has now been found that a compound which is relatively easily detachable from the tissue by treatment with hot, dilute soda solution is obtained if a glycol or polyglycol ether acylated in the hydroxyl group of a p-oxy-benzoic acid with a water-soluble salt of the 4,4-di aminostilbene-2, 2'-disulfonic acid condensed.



  I) he preparation of such a starting material can be carried out in such a way that an ester of para-hydroxy-benzoic acid with one or more moles of alkylene oxide, eg. B. ethylene oxide or another agent 1 which introduces the oxalkoxy groups and saponified the alkoxylated ester obtained. The free hydroxyl group of the alkoxylated side chain of the acid obtained is then acylated with the anhydride or acid halide of an aliphatic, aromatic, aromatic-aliphatic, hydroaromatic or heterocyclic carboxylic acid.



  The acylated glycal or polyglycol ethers of p-oxy-benzoic acid obtained in this way can contain further substituents in the benzene nucleus which cause increased solubility in water, such as B. alkyl or alkoxy groups, have and are in the usual way, for. B. with thionyl chloride or phosphorus halides in the acylated glycol or polyglycol ethers of the p-oxy-benzoic acid halides and condensed with a water-soluble salt of 4, 4 'diamino-stilbene-2, 2'-disulfonic acid in the usual way.

   A product obtained in this way has the following constitution:
EMI1.1
 R = aliphatic radical n = 1 to 10 Me = monovalent metal
example
152 parts of ep-oxybenzoesa, urem.ethy] ester are heated to 130-140 ° C., 0.5 parts of alkali metal are added as a catalyst and 48 parts of ethylene oxide are introduced into the melt. The reaction product obtained, which has a consistency similar to vaseline, is then saponified with lye.

   The free p-oxethoxy-benzoic acid is precipitated from the filtered solution with mineral acid in a yield of about. 95% It can be recrystallized from water for further purification. Thin, shiny leaves. F 175 to 177 C.



   40 parts of p-oxethoxy-benzoic acid are mixed with 120 parts of acetic anhydride in counter-wa. rt acetylated by concentrated sulfuric acid and the reaction mixture worked up according to the usual methods. Yield about. 97%. Thin leaflets (made from plenty of water).



  F 169-170 C.



   18 parts of p-acetoxethoxy-benzoic acid are heated under reflux with 50 parts of thionyl chloride. After driving off the excess thionyl chloride, if both reaction components were pure, an almost colorless, syrupy acid chloride is obtained which solidifies to colorless crystals after standing in the cold for a while. Yield about 90% F 63-64 C; Bp 0.3 mm 136-138 C
12 parts of the sodium salt of 4,4'-diaminostilbene-2, 2'-disulfonic acid are dissolved in 70 parts of water and 6 parts of soda, dissolved in 15 parts of water, and 80 parts by volume of acetone are added. 18 parts of p-acetoxethoxy-benzoylchloride dissolved in 18 parts of acetone are added dropwise to the mixture, which has been heated to about 25 ° C., and the mixture is stirred for a further half hour and filtered.

   4,4 '- (Bis-p Acetoxäthoxybenzoylamino) -stiblen-2,2'-disulfonic acid is obtained in about 90% yield in the form of its sodium salt as a pale yellow powder, which is absorbed from water on cellulose fibers and gives them a high Gives whiteness.



   When the fabrics treated with these compounds are boiled with soap solution or under the usual conditions of a hot wash, the ester groups are more or less completely split, with the now free hydroxyl group. The outstanding condensation product has increased water solubility and is largely detached from the fiber.



      PATENT APPLICATION
Process for the production of an optical brightening agent, characterized in that 4,4'-diamino-stilbene-2,2'-disulfonic acid is substituted with a glycol or polyglycol ether acylated in the hydroxyl group of a p-oxybenzoic acid halide, which is optionally further substituted in the core , is condensed.

 

Claims (1)

SUBCLAIMS 1. The method according to claim, characterized in that the glycol or polyglycol ether of the p-oxy-benzoic acid halide which is condensed has alkyl groups in the nucleus. 2. Method according to claim, characterized in that the glycol or polyglycol ether of the p-oxybenzoic acid halide which is condensed has alkoxy groups in the core. 3. The method according to claim, since durci gekennzeiehnet that the glycol or polyglycol ether of the p-O. x y-benzoic acid is eylated with the best of an aliphatic carboxylic acid. 4. The method according to claim, characterized in that the glycol or polyglycol ether of p-oxy-benzoic acid is acylated with the remainder of an aromatic carboxylic acid. 5. The method according to claim, since dureh characterized daL ', the glycol or polyglycol ether of p-oxy-benzoic acid is acylated with the remainder of an aromatic-aliphatic carboxylic acid. 6. The method according to patent claim, characterized in that the glycol or polyglycol ether of p-Oxv-benzoic acid is acylated with the remainder of a hydroaromatic carboxylic acid. 7. The method according to patent claim, characterized in that the glycol or polyglycol ether of p-oxy-benzoic acid is acylated with the remainder of a heterocyclic carboxylic acid.