CH397716A - Process for the preparation of γ-lactones-α-carboxylated - Google Patents

Description

The subject of the present invention is a process for the preparation of α-carboxylated y-lactones corresponding to the general formula

in which R represents an alkyl or alkenyl radical comprising from 4 to 10 carbon atoms.

Composes them. of formula I are new substances which serve to flavor fatty foodstuffs.

The process according to the invention consists in condensing an epoxide of formula

wherein R1 represents an alkyl or alkenyl radical comprising from 4 to 10 carbon atoms, together with an alkaline salt of a di-alkyl ester of malonic acid to form an α-carbalkoxy-y-lactone bearing the substituent R1 in position y, to saponify this carbalkoxy-lactone by alkaline route and to acidify the salt obtained in order to liberate and lactonize the hydroxy-dicarboxylic acid.

This process can be carried out in the following way: an prepares the malonic fester salt, for example the sodium salt of ethyl malonate, by causing sodium methylate to act on the ethyl malonate in a solvent such as benzene and removing the methyl alcohol formed by distillation. The epoxide II is then added to the solution of sodium ethyl malonate obtained and the condensation is carried out by heating at a temperature between 70° and 800° C. The sodium salt of an α-carbethoxy-y-lactone is thus obtained. which is decomposed by treating it with acetic acid.

The saponification of the (x-carbethoxy-y-lactone can be done by two methods, one of which consists in heating the carbalkoxy-lactone with an alcoholic alkali, for example ethanolic potash, at the reflux temperature of the According to the other method, an heating of the carbalkoxy lactone with a concentrated aqueous alkali, for example aqueous caustic soda, at a temperature between 700 and 800 C. Saponification of the carbalkoxy group is accompanied by the opening of the lactonic ring so that the alkaline salt of a hydroxy-dicarboxylic acid is obtained.This salt is treated with an aqueous mineral acid, for example sulfuric acid, to liberate the dicarboxylic acid and lactonize it.

The following examples illustrate the implementation of the invention.

Example 1 <I>a)</I> Preparation <I>of</I> a-carbethoxy-y-decalactone In a flask with 3 ground necks, uruniRTI ID="0001.0268" WI="7" HE= "4" LX="1725" LY="2111"> a stirrer, a thermometer, a short column - followed by a descending condenser and a container - are loaded, by shaking and by cooling with water, 1000 ml of benzene, 54 g of sodium methylate (1 coole) and 320 g of ethyl malonate (2 cooles). The mixture is heated to 80°C and about 700 ml of benzene is distilled. The duration of the distillation is 5 Neures. Distilled benzene contains 30.5 g of methyl alcohol (= 94% of theory).

The flask is cooled to 500° C. and 64 g of epoxy-1,2-octane (0.5 coole) are introduced. The mixture is stirred for 5 hours at 70-80° C. and then the remainder of the benzene is distilled; an collects about 250 ml which contains 17.5 g of ethyl alcohol (= 75% of theory). The reaction mixture is very thick. The decomposition of the sodium salt of the α-carbethoxy-,t-decalactone formed as an intermediate is carried out by acidifying the reaction mixture with 70 ml of glacial acetic acid. The product thickens again, then after a few minutes it becomes more and more fluid. The solution is diluted by adding 500 ml of water and the product is extracted with benzene, then the extract is washed once with water. This washing is in turn exhausted with benzene. The benzene is then flushed out with a water pump. 331 g of a mixture of a-carbethoxy-y-decalactone and ethyl malonate are obtained. This mixture is distilled under vacuum and 99 g (0.408 mol) of a-carbethoxy-y-decalactone distilling at 118-135° C. under 0.005 to 0.01 mm Hg are collected. The product obtained has the following properties

<I>b)</I> Preparation <I>of</I> α-carboxy-γ-decalactone In a flask, stirred at 70-800 C. For 1 1/2 h, a mixture of 100 g of a-carb@thoxy-y-decal-lactone (0.412 mole) and 40 g of caustic soda dissolved in 250 cc of water. The mixture is then acidified with 100 cc of 50 ()/o sulfuric acid, at a temperature of 20-25° C. The carboxy-lactone is in solution in the mixture which is exhausted twice. with 250 cc of chloroform. The extract is washed with dilute brine until neutral, the solvent is removed under vacuum and the residue is dried for 30 hours at 30-500 C, under a vacuum of about 2 mm Hg. a-carboxy-y-decalactone brate, m.p. = 45-560 C.

The carboxy-lactone brate is dissolved in 50 cc of chloroform at 50-6011 C and then added to the solution at the same temperature, 400 cc of petroleum ether. The mixture is then allowed to stand for 2 hours. White crystals are deposited in abundance. The mixture is hoisted overnight and cooled the following morning in an ice-salt mixture for 3 hours. The crystalline product is drained and then washed with 400 cc of petroleum ether (E. 60-80 C) and dried at room temperature. 0n obtains 71.6 g (0.334 mol) of purified a-carboxy-y-decalactone; F = 59.5-61.5- C and 60.6-62.3 C after a second recrystallization, 1.A. = 260.8.

Example 2 <I>a)</I> Preparation <I>of</I> 1'-carbethoxy-y-octalactone The formation of the sodium salt and the condensation with the epoxide are carried out as described in Example 1 using 1000 ml of benzene, 320 g of ethyl malonate (2 cooles), 54 g of sodium methylate (1 coole) and 55 g of epoxy-1,2-hexane (0. 5 cool). 293.8 g of a mixture of α-carbethoxy-γ-octalactone and ethyl malonate are obtained. 0n distills this mixture under vacuum and collects 44.9 g (0.2l coole)RTI ID="0002.0274" WI="44" HE="4" LX="477"LY="2527"> of (x- carbethoxy-y-octalactone distilling at 102-115.1 C under 0.001 to 0.01 mm Hg. This product has the following properties

<I>b)</I> Preparation <I>of</I> α-carboxy-,1-octalactone 0n saponifies and lactonizes 90.7 g of α-carb6thoxy-γ-octalactone (0.422 mol) with 40 g of caustic soda in 300 cc of water under the conditions indicated in example 1. 0n thus obtains 73.7 g (0.395 mol) of -carboxy-γ-octalactone. By recrystallization as described in Example 1, an obtains the pure product F=48-500 C, 1.A. = 299.9; I.E. = 302.8. Example 3 <I>a)</I> Preparation <I>of</I> α-carbethoxy-γ-nonalactone The formation of the sodium salt and the condensation with the epoxide are carried out according to example 1 , using 1000 ml of benzene, 54 g of sodium methylate (1 mole), 320 g of ethyl malonate (2 moles) and 62.7 g of epoxy-1,2-heptane (strength 900 /0; 0.5 mole). 0n thus obtains 313.6 g of a mOange of a-carbethoxy-y-nonalaotone, distilling between 108o and 1230 C under 0.001 to 0.01 mm Hg. The product obtained has the following properties

<I>b)</I> Preparation <I>of</I> 1'-carboxy-γ-nonalactone The saponification as well as the lactonization are carried out in accordance with Example 1, using 100 g of a-carbethoxy -y-nonalactone (0.431 male) and 40 g of caustic soda dissolved in 300 6c of water. 0n obtains 86.1 g of crude product, mp = 35-42 C which is then recrystallized from a mixture of chloroform and petroleum ether. 0n obtains 53.9 g (0.269 mole) of (x-carboxy-y-nonalactone M.p. = 45.7-48.30 C; I.A. = 278.2; I.E. = 282.5.

From the mother waters, an obtained, by decarboxylation, 20.8 g of y-nonalactone.

Example 4 <I>a)</I> Preparation <I>of</I> a-carbethoxy-y-(trimethyl-1',3',3'-butyl)-butyrolactone Formation of the sodium salt and The condensation is carried out according to Example 9, using 160 g (1.0 coole) of ethyl malonate, 54 g (1.0 coole) of sodium methylate, 800 cc of benzene and 71.1 g (0 ,5 coole) of epoxy-1,2-trimethyl-3,5,5-hexane. 0n obtains <B>157</B> g of a mixture which is distilled under vacuum. 0n collects 19.3 g of -carbethoxy-y-(trimethyl-1,3,3-butyl)-butyrolactone.

<I>b)</I> Preparation <I>of</I> a-carboxy-y-(trim@tizyl-1',3',3'-butyl)-butyrolactone Saponification, lactonization and the crystallization takes place under the conditions indicated in Example 1. From 19.3 g of a-carbethoxy-y-(trimethyl-1',3',3'-butyl)-butyrolactone, an <B>17.1</B> g of a-carboxy-y-(trimethyl-1',3',3'-butyl)-butyrolactone beute, Mp = 71-86 C. The pure product obtained by recrystallization, melts at 100.5-104.8 C, 1.A. = 243.6;<B>1.E.</B> = 240.5.

Claims (3)

CLAIM Process for the preparation of α-carboxyMe γ-lactones corresponding to the general formula in which R represents an alkyl or alkenyl radical comprising from 4 to 10 carbon atoms, characterized in that an epoxide of the form in which R1 represents an alkyl or alkenyl radical containing from 4 to 10 carbon atoms, with an alkaline salt of a di-alkyl ester of malonic acid to obtain an α-carbalkoxy-y lactone bearing the R1 substituent in the y position , this carbalkoxy-lactone is saponified alkaline and the resulting salt is acidified to liberate and lactonize the hydroxy-dicarboxylic acid. SUB-CLAIMS 1. Process according to claim, characterized in that the alkanol is eliminated by distillation as it is formed in the condensation. 2. Process according to claim and sub-claim 1, characterized in that the a-carbalkoxy-y-lactone is saponified by heating it with an alcoholic alkali and that the salt of the hydroxy-dicarboxylic acid is lactonized by the action of a mineral acid. 3. Process according to claim and sub-claim 1, characterized in that the a-carbalkoxy-y-lactone is saponified by heating it with a concentrated aqueous alkali at a temperature comprised between 70o and 80o C and that urirral acid is made to act on the salt obtained.