DD156182A1 - PROCESS FOR PREPARING DERIVATIVES OF 1,2-BIS- (BENZOXAZOLYL) -ETHYLENE - Google Patents

Abstract

The invention relates to an improved process for the preparation of derivatives of 1,2-BIS- (benzoxazolyl) -ethylene of the formula I. They are obtained by reacting fumaric acid, maleic acid, acetylic acid or functional derivatives of these dicarboxylic acids with o-hydroxy-aminoaryl compounds , The reaction takes place in a single-stage process according to the invention in an ethylene glycol-zinc chloride suspension.

Description

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VEB CPiEMIEKOMBINAT BITTERFELD

Bitterfeld, 4. 2. 1981 2127

Process for the preparation of derivatives of 1,2-bis (benzoxazolyl) ethylene

Field of application of the invention

The invention relates to an improved production process for 1 _y 2 ~ bis (benzoxazolyl) ethylene derivatives of the general formula

-CH = CH-C O ^ ^x 0

-2-

227492 6

- 2 - 2127

wherein X is hydrogen or a non-aromatic hydrocarbon radical having at most β carbon atoms.

Chara kteristik the "known technical solution

As is known, 1,2-bis- (benzoxazolyl) -ethylene compounds of the formula I are obtained by reacting o-hydroxyaminoaryl compounds with fumaric acid. Maleic acid, malic acid or functional derivatives of these dicarboxylic acids. The two substituents X can be identical or different and are hydrogen or lower. Alkyl groups, the latter may still be branched mean. The reaction takes place in liquid halogenated aromatic hydrocarbons under a nitrogen atmosphere. In this process, additives of boric acid, p-toluenesulfonic acid or phosphoric acids have a very favorable effect. The reaction is initiated by gradually heating the reaction mixture to the boiling point of the solvent and continued until almost the theoretically cleavable amount of water is distilled off azeotropically. In this process, the desired compounds are obtained in good yields in some cases, but occur while fluorescent by-products, which greatly limit the Aufhellwirkung or make impossible when using the synthesis products as optical brightener. The existence of these by-products can be detected chromatographically.

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Furthermore, it is known that in addition to the above single-step process, the synthesis of the desired compounds can also be carried out in two or more stages to isolate various intermediates. Even when using the above reaction conditions and additives occur in multi-step process disturbing fluorescent by-products. Only the execution of the final reaction step, the cyclization / in an aqueous zinc chloride melt leads to a final product with a low proportion of additional fluorescent by-products. These multi-stage processes are uneconomical and technically difficult to realize because of the greater apparatus and time required, especially the melting stage.

Object of the invention

The object of the invention is an economical process for the preparation of 1,2-bis (benzoxazolyl) ethylene compounds in which the end products are obtained in a one-step process without fluorescent lifting products and are suitable for use as optical brighteners without restriction are.

Principle of the Fiction ndu ng

It has been found that 1,2-bis (benzoxazolyl) ethylene derivatives of the general formula I in which X = Y / oxygen or a non-aromatic hydrocarbon radical having at most 6 carbon atoms, in a one-step process with high yield and for use as optical

- A - *> L · / q Ό C U 2127

Brightener can produce excellent quality, if one carries out the reaction of the starting materials in an ethylene glycol-zinc chloride suspension with exclusion of air "at temperatures between 145 ⁰ C and 170 ⁰ C. The addition of ethylene glycol to the zinc chloride melt causes the good stirrability of the suspension and For this reason, the construction of special reaction vessels is also omitted in the technical realization.

A further addition of an organic solvent from the group of aromatic hydrocarbons, including their chlorinated compounds, from 5 to 15% of the amount of ethylene glycol used towards the end of the reaction leads to a significant improvement in the yield while maintaining good quality.

After working up the suspension in aqueous hydrochloric acid solution, the end product is obtained in high yield and contains no by-products which interfere with the use as optical brightener. Further advantages of the process are the implementation of the reaction in only one stage, as well as the execution of the process at lower temperatures than in the reaction in boiling organic solvents.

2127

Embodiments Example 1

200 g of anhydrous zinc chloride, 29.4 g of maleic anhydride and 73.8 g of 1-amino-2-hydroxy-5-methylbenzene are introduced into a stirred flask and the flask contents are flushed with nitrogen gas for 30 minutes. 160 ml of ethylene glycol are then added to the flask, heated to 145 G while stirring, passing a nitrogen flow of 10 l / h through the flask.

The temperature of the contents of the flask is increased to 170 ^° C. with stirring while stirring for 12 hours. During the heating, 20 ml of chlorobenzene are added dropwise to the flask at 165 ^° C. in the course of 10 minutes.

After the reaction time of 12 hours, the mixture is cooled to 100 ^° C., the nitrogen stream is removed and 320 ml of 2% hydrochloric acid at a temperature of 80 ^° C. are passed to the contents of the flask. The resulting slurry is then poured into 3200 ml of 2% hydrochloric acid at a temperature of 70 to 80 ⁰ C. It is stirred for 1 h at this temperature, filtered off with suction and washed with water acid-free. The precipitate is dried at 80 to 90 ⁰ C.

Yield: 70.5 g (= 81 %) " " Melting point: 184 to 186 ^° C.

Example 2

Same procedure as example 1, only use of 34.8 g of maleic acid instead of maleic anhydride Yield: 72.2 g (83 % of theory ) Melting point: 184 to 186 ^° C.

74 92 6

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Example 3 ι

Same procedure as example 1, only use of 34j 8 g of pumaric acid instead of maleic anhydride. Yield: 73.1 g (84 % of theory ) Melting point: 185 to 187 ^° C.

Claims (3)

invention claim 1 · Process for the preparation of 1,2-bis (benzoxazolyl) · ethylene derivatives of the formula C-CH = GH-C / wherein X = hydrogen or a non-aromatic hydrocarbon radical having at most 6 C-atoms, by reacting fumaric acid, maleic acid, malic acid or a functional derivative of these dicarboxylic acids with an o-hydroxy ~ aminoaryl compound in a one-step process, characterized in that the reaction carried out in an ethylene glycol-zinc chloride suspension with exclusion of air. 2127 2. The method according to item 1, characterized in that the reaction takes place at temperatures between 145 ⁰ C and 170 ⁰ C. 3. The method according to points 1 and 2, characterized in that the reaction mixture towards the end of the reaction, an organic solvent from the group of aromatic hydrocarbons, including their chlorinated compounds, in an amount of 5 to 15 %, based on the ethylene glycol added becomes.