HU196943B - Process for production of 2-hydroxi-4-oktiloxibenzophenon - Google Patents

Abstract

2-Hydroxy-4-octyl-oxy-benzophenone is prepd. by alkylating 2,4-dihydroxy-benzophenone with n-octyl-chloride in a high-boiling alcohol, pref. butanol, in the presence of at least 3 wt. equivs. water-free sodium carbonate for the amt. of 2,4-dihydroxy-benzophenone used. Reaction takes place with constant stirring at the b.pt. of the alcohol, the reaction mixt. is subsequently cooled to 90-100 deg.C, an aq. soln. contg. 3 wt.% dithionite based on the starting material is added and boiling continued for at least further 10 mins. The reaction mixt. is now cooled to 65-85 deg.C and the two phases are sepd. On cooling the alcohol phase to O deg.C the resulting 2-hydroxy-4-octyl-oxy-benzophenone forms a crystalline ppte. which is filtered and washed.

Description

The present invention relates to a process for the preparation of 2-hydroxy-4-octyloxy benzophenone.

It is known that plastics are damaged by light, in particular by ultraviolet radiation, due to degradation processes (so-called degradation). To prevent this, light-stable isomers have been used, of which the derivatives of 2,4-dihydroxybenzophenone (hereinafter "DHB") have proved their worth, e.g. 2-hydroxy-4-octyloxybenzophenone (hereinafter "HOB"); this compound is currently used in the highest amounts, so industrial use! production is also needed. This material is also used in the manufacture of plastic films, in the case of transparent or colorless films, with the proviso that the stabilizer should be colorless.

The 2-hydroxy-4-octyloxybenzophenone (HOB) requires 4-alkylation of 2,4-dihydroxybenzophenone (DHB). This reaction is generally carried out with an alkyl halide in a ketone solvent.

Such a production process is known in U.S. Patent No. 1806,870. from the German Federal Publication. The technology involves reacting dihydroxybenzophenone with alkyl chloride in methyl isobutyl ketone in the presence of an iodide catalyst (quaternary ammonium iodides).

No. 1,901,482. The German Federal Publication also discloses a process for converting the above starting materials into the corresponding end product in cyclohexanone.

Both solutions have the disadvantage that the yield is low (49-80%) and the resulting material is highly colored.

In order for the alkylation process to be conducted in good yield, it is very important to deactivate the water formed during the reaction, which is formed by the decomposition of NaHCO ₃ , since if water is added to the reaction mixture, it will hydrolyze the alkyl chloride and thus reduce the efficiency of the process. Obviously, dewatering in industrial practice is a strong dehydrating agent, e.g. calcium oxide. Because CaO (or similar oxide) damages the starting DHB, dehydration for HOB production cannot be achieved in this manner.

It is an object of the present invention to provide a process for the removal of water produced during the alkylation of DHB, which degrades the production of the HOB target compound in a simple and appropriate manner.

The water to absorb or bind to carbonate for this process lejátszatására relatively low temperature interval bicarbonate reaction, but has the disadvantage of this solution is that the Na ₂ CO ₃ of formed by the water uptake of _NaHCO3 at relatively low temperatures, eg. At about 60 ° C, decomposes (GMELIN's Handbuch dér anorganischen Chemie, System No. 21 SODIUM;

8. Auflage, 1958) with water decomposition, the rate of this decomposition increases with increasing temperature. Therefore, this risk also exists during the manufacturing process of the present product and therefore its elimination is a very important requirement.

Surprisingly, we found during our experiments that generated the anhydrous sodium carbonate used as a dehydrating agent under reaction conditions for sodium bicarbonate either decomposes used in an excess of Na ₂ CO ₃ upon medium around 120'C temperature, as water is formed, so that the sodium carbonate dehydrating (water-binding agent) can be used in the preparation of HOB. This result is explained by the fact that, in a butanolic medium, a large excess of solvent at boiling point (about 120 ° C), e.g. anhydrous sodium carbonate, taken in at least three equivalents by weight, binds the same formed carbon dioxide in the form of sodium bicarbonate to the water formed during the alkylation of DHB. This is evidenced by the fact that the DHB with equivalents formed _NaHCO3 analytical determination. The recognition described above made it possible to ensure the absence of alkylation, i.e., to prevent the hydrolysis of the alkyl halide. The result obtained was further improved by using potassium iodide as the catalyst and triethylamine as the phase transfer catalyst, thereby increasing the alkylation efficiency to 90%.

According to our method, 2,4-dihydroxybenzophenone in butanol is mixed with n-octyl chloride in an amount of at least three equivalents based on the starting benzophenone, in the presence of anhydrous sodium carbonate, potassium iodide catalyst and triethylamine phase transfer catalyst for at least 12 hours through alkylation. The reaction mixture is then cooled to 100 ° C and sodium dithionite (at least 4% by weight, based on 2,4-dihydroxybenzophenone) is added in aqueous solution and refluxed, cooled to 70-80 ° C and the two phases are separated. the solvent solution was cooled to 0 ° C and the precipitated colorless crystalline 2-hydroxy-4-octyloxybenzophenone was filtered off and washed with methanol and water.

In this way, a white crystalline product was obtained in 90% yield.

Details of our procedure are illustrated in the following example.

Example

300 ml of n-butanol, 150 g of DHB (94% purity), 7 g of potassium iodide, 5 g of triethylamine, 112 g of anhydrous sodium carbonate and 130 g of n-octyl chloride are stirred in a refluxing vessel for 15 hours. while boiling. The mixture was cooled to 100 ° C, water (250 ml) and sodium dithionite (7 g) were added and the mixture was refluxed for an additional 15 minutes. After cooling the reaction mixture to 70-80 ° C, the aqueous phase is removed. The butanolic solution was cooled to 0'C and then recovered by crystallization of activated crystalline 2-hydroxy-4-octyloxy-benzophenone, washed with methanol and water. The HOB yield is 194 g, 90% based on the starting DHB.

Claims (1)

A patent claim Process for the preparation of 2-hydroxy-4-octyloxy-benzophenone by alkylation of 2,4-dihydroxy-benzophenone with n-octyl chloride in the presence of alkali carbonate and catalysts, characterized in that the starting 2,4-dihydroxy - at least three equivalents by weight of anhydrous sodium carbonate to benzophenone, stirring at the boiling point of the alcohol, cooling the reaction mixture to 90 ° C to 100 ° C, adding an aqueous solution of at least 4% w / w dithionite starting material and refluxing then cooled to 65-85 ° C, the aqueous layer was separated, the n-butanol solution was cooled to 0 ° C, and the resulting crystalline 2-hydroxy-4-octyloxy-benzophenone was collected by filtration and washed.