DD202141A5 - PROCESS FOR THE PREPARATION OF 3,3-DIMETHYLGLUTARIC ACID - Google Patents

Abstract

1. Process for the production of 3,3-dimethyl glutaric acid from isophorone, characterized by treating isophorone with hydrogen peroxide in the presence of strong acids at temperatures of from 10 to 80 degrees C.

Description

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Process for the preparation of 3t3-Diffl-Qth; yIgIutaric acid Field of application of the invention;

The invention relates to a process for the preparation of 3 j 3-Dinie thy iglutaric acid from isophorone.

Characteristic of the known technical solutions;

3,3-Dimethylglutarsäure and their esters are intermediates in the production of pesticides (DE-OS 28 13 341). Furthermore, they are suitable as an additive for lubricating oil (US Patent No. 2,971,915).

It is known to treat isophorone with HpOp in alkaline medium (E.D. Temple, J. Org. Chem., 5, 1275). In this case, a yield of 92% of 3,3-dimethyl-5-oxo-hes: acid is obtained »On the other hand, various methods are known for the preparation of 3,3-DimethyIglutarsäure from the literature. Thus, according to W.T.Smith and G.L. McLeod, Org. Synthesis 31, 40 (1951) by oxidation of dimedone (5,5-dimethyl-1,3-cyclo)

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hexandione) with sodium hypochlorite 3,3-diae-thiol glutaric acid. FBThole and JFThorpe, J. Chem. Soc. 22 "^ ²² (1911) obtained dimethylglutaric acid from acetone and cyanoacetamide. WHPerkin jun. and JFThorpe, J.ehem.Soc, £ 5 »4s (1899) make dimethylglutaric acid from dimethylacrylic ester and cyanoacetic ester.

All of these known processes have disadvantages, for example, that they either start from expensive adducts or run over several stages of synthesis or bring low yields, produce a lot of waste salt as a by-product or supply highly contaminated end product _{or the like} .

Object of the invention:

The aim of the present invention is to produce 3,3-dimethylglutaric acid, starting from isophorone, in a simple manner.

Explanation of the essence of the invention:

According to the invention this is achieved by treating isophorone with hydrogen peroxide in the presence of strong acids at temperatures of 10 to 80 ° G.

Strong acids are proton acids (Brönsted acids) which have a pKa of 2.5 or less and which are stable to hydrogen peroxide, such as sulfuric acid, phosphoric acid, nitric acid, organic sulfonic acids such as benzenesulfonic acid, trichloroacetic acid, trifluoroacetic acid and the like. Preference is given to the use of sulfuric acid.

For the implementation of the reaction, in a first step, a mixture of water, hydrogen peroxide and a strong

Acid prepared by combining a solution of hydrogen peroxide, an acid or an aqueous solution of an acid and possibly water. "

Hydrogen peroxide is used as an aqueous solution, whereby the concentration can vary within a wide range from 20% to approximately 85%. Preference is given to technically available concentrations of 30% and 70% HpC ^ in water,

The strong acid can be used in pure form or as an aqueous solution. In the case where sulfuric acid is used as the strong acid, technical concentrated sulfuric acid is preferably used.

The amounts and concentrations of Wasserstoffperoxidlös ung, strong acid and optionally water are chosen so that for 1 mole of isophorone 4-8 moles of hydrogen peroxide, 4-8 moles of acid and 20-40 moles of water.

The preferred ratio is 5-6 moles of hydrogen peroxide, 5-6 moles of sulfuric acid and 30 moles of water per 1 mole of isophorone

The reaction temperatures are suitably chosen between 20 and 50 ⁰ G.

The process according to the invention gives 3 * 3-dimethylglutaric acid in a purity of more than 80 % and in a yield of more than 75 % ,

EXAMPLES

In several embodiments, the invention will be explained in more detail below.

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example 1

In a three-necked flask 166.3 g of 95% HpSO ^ were submitted. 200 g of 30% strength hydrogen peroxide were added dropwise with cooling to 10 ° C. * During one hour, 40 g of isophorone (99% pure) were metered in so that the temperature remained constant at 25 ° C. After the addition, the temperature was progressively increased to 58 ⁰ C;

at this temperature, the reaction mixture was stirred for a further 16 hours. The mixture was cooled to -10 ⁰ C and the crystal slurry is suction filtered. The crystals contained 23.32 g of dimethylglutaric acid.

The purity of the product was 82%,.

The mother liquor was extracted (after peroxide destruction by bubbling with SOp) three times with 120 ml of ether after addition of conc. "NaOH to pH 1.5".

The extract after evaporation of ether still contained 7.4 g as 100 % pure calculated Dirnethylglutarsäure. The total yield, based on the amount of isophorone used, was 57 j 8%. ,

Example 2

In a three-necked flask, 280 g of 56% H ₂ SO _{2 were placed} before ge. To this was added dropwise with cooling to 10 ⁰ G 85 g of 70% hydrogen peroxide. During one hour, 40 g of isophorone were added so that the temperature remained between 25 and 30 ⁰ G. After the addition, the temperature was progressively increased to 58 ⁰ C; at this temperature, the reaction mixture was stirred for a further 5 hours. The mixture was slowly cooled to -10 ⁰ G and the crystal slurry sucked off. The crystals contained 29.7 g of dimethylglutaric acid with a content of 82.3%.

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GO, with internal standard, corresponding to 24,44 formed Dime thylgl utarsäiire ο

The mother liquor was (after Peroxidvernichtung by By "blow SOP) after addition of conc ₀ NaOH to pH 1.5 three times extracted with 120 ml ether.

After evaporation, a further 7 »50 g of dimethylglutaric acid can be detected in the extract with GC. Together, 31.9 ^ · S of dimethylglutaric acid were formed, corresponding to a yield of 68.9 % relative to the isophorone used.

Example 3

A flask was charged with 83 g of 85% phosphoric acid. To this was added dropwise 100 g of 30% hydrogen peroxide. During one hour, 20 g of isophorone were metered in so that the temperature remained between 25 and 35 ^° C. At the end of the addition, the reaction mixture was further stirred at room temperature. "The temperature in the flask first rose to 50-55G. then it slowly sank for 3 to 5 hours.

The colorless to slightly yellow solution was freed of peroxides by treatment with SO 4 and the pH was adjusted to 1.5 with conc. NaOH. The formed dimethyl glutaric acid was isolated by extraction with ether. According to the gas chromatographic analysis, the residue after evaporation contained 8.87 g of dimethylglutaric acid, corresponding to a yield of 38.3%, based on isophorone used.

Claims (4)

23971 claim for invention: 1. A process for the preparation of 3,3-Di ^ ethyIglutarsäure from isophorone, characterized in that treating isophorone with hydrogen peroxide in the presence of strong acids at temperatures of 10 to 80 ⁰ O. 2. The method according to item 1, characterized in that one uses as strong acid sulfuric acid, Method according to item 1, characterized in that a molar ratio of isophorone to hydrogen peroxide to strong acid was used from 1 to 4 to 8 to 4 to 8 4. The method according to item 1 to 3, characterized in that one works at temperatures of 20 to 30 ⁰ C.