JP3679238B2 - Method for purifying γ-alkyl-γ-lactone - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for purifying γ-alkyl-γ-lactone having a bad odor and the like and obtaining a high quality γ-alkyl-γ-lactone that can be used as a fragrance or the like in a high yield.
[0002]
[Prior art]
γ-Alkyl-γ-lactone generally has a fruit-like aroma and is useful as a fragrance or flavor, or as a synthetic raw material for fragrances, pharmaceuticals, agricultural chemicals, and the like. Here, γ-alkyl-γ-lactone exhibits a flavor and sour taste that reminds plastic that its purification is insufficient depending on the synthesis method, so when used as a fragrance, particularly a food additive, It is necessary to sufficiently remove these flavors and sourness and to have satisfactory quality with the original aroma of γ-alkyl-γ-lactone.
[0003]
Conventionally, as a purification method of γ-alkyl-γ-lactone, a lactone ring is once saponified with an alcoholic potassium hydroxide solution to form a free acid salt, an insoluble matter is separated and then returned to a lactone with dilute sulfuric acid, Alternatively, a method of lactonization after isolation and purification with sodium oxyacid salt is known (Osamu Okuda, “Perfume Chemical Review”, Yodogawa Shoten, Vol. 2, page 1193). However, this method has a problem that the operation is complicated and a large amount of salt is generated as waste.
[0004]
As another purification method for γ-alkyl-γ-lactone, there is a method using precision distillation as in the case of most fragrances. However, when γ-alkyl-γ-lactone is used as a flavoring agent, especially as a food additive, the flavor and sourness that reminds us of plastic are avoided, and these are completely removed and purified to a satisfactory level. However, there is a problem that the precision distillation is not efficient and the yield is low.
[0005]
[Problems to be solved by the invention]
Accordingly, an object of the present invention is to provide an efficient purification method for obtaining γ-alkyl-γ-lactone of satisfactory quality as a perfume, particularly as a food additive.
[0006]
[Means for Solving the Problems]
Under such circumstances, the present inventors have conducted extensive research to solve the above problems, and as a result, by treating γ-alkyl-γ-lactone, which has a strange odor and sour taste, with a metal alkoxide, this strange odor and sour taste can be removed. The present inventors have found that a high quality γ-alkyl-γ-lactone satisfying the above requirements can be obtained in a high yield, and the present invention has been completed.
[0007]
That is, the present invention is, .gamma. alkyl -γ--lactone were mixed with stirring metal alkoxide, there is provided a method for purifying .gamma. alkyl -γ- lactone, characterized in that the distillation.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
The method of the present invention can be applied to γ-alkyl-γ-lactone produced by any reaction method, for example, a method of reducing γ-keto acid [Zhur Obschchei Khim., 31, 984 (1961)], Method of heating γ-alkyl unsaturated carboxylic acid with sulfuric acid (Japanese Patent Publication No. 38-4060), Method of radical addition reaction of alcohol and acrylic acid or methyl acrylate [Izvest. Akad. Nauk. SSSR, Otd. Khim Nauk., 187x (1962)], a method of adding acrylic acid ester as a raw material and adding sulfonic acids as a catalyst (Japanese Patent Publication No. 53-36466), a method of adding phosphate and / or sulfate as a catalyst [ Japanese Patent Publication No. 52-42794], a method in which acrylic acid or an acrylic ester is used as a raw material and zinc halide is added as a catalyst [Japanese Patent Laid-Open No. 4-54177], acrylic acid and primary or secondary alcohol or A mixture of those It may be applied to those produced by any method such as a method [JP-A 8-231525 discloses] to presence heated reaction peroxide.
[0009]
Among these, the method of the present invention is preferably applied to γ-alkyl-γ-lactone obtained by a method in which acrylic acid and alcohol are heated and reacted in the presence of ditertiary butyl peroxide. Examples of the primary alcohol used as a starting material in the present method include those having 5 to 10 carbon atoms, specifically n- (or iso) amyl alcohol, n- (or iso) hexanol, n- (or iso). ) Heptanol, n- (or iso) octanol, n- (or iso) nonyl alcohol, n- (or iso) decyl alcohol and the like. When primary alcohol is used, the resulting lactone is γ-mono Alkyl-γ-lactone is obtained. Examples of the secondary alcohol include those having 5 to 10 carbon atoms, specifically, sec-amyl alcohol, 2-hexanol, 2-heptanol, 2-octanol, sec-nonyl alcohol, sec-decyl alcohol and the like. When a secondary alcohol is used, the resulting lactone is γ-dialkyl-γ-lactone. The amount of these alcohols used is preferably in the range of 3 to 8 mol, particularly 4 to 7 mol, per 1 mol of acrylic acid. The amount of ditertiary butyl peroxide used is preferably 0.01 to 0.5 mol, particularly 0.04 to 0.2 mol, per mol of acrylic acid. This reaction is preferably carried out at a reaction temperature of 140 to 200 ° C, particularly 155 to 185 ° C.
[0010]
The γ-alkyl-γ-lactone to be purified by the method of the present invention may be a reaction mixture itself containing γ-alkyl-γ-lactone or a product purified by a conventional purification method after completion of the reaction. Examples of purified products are those that are still inadequate after purification by conventional methods, those that have failed odor in quality inspection after rectification, those that have deteriorated during storage and have a bad smell, acidity, etc. Examples include impurities that do not detect impurities in gas chromatography but have a strange odor or acidity. Examples of γ-alkyl-γ-lactone compounds that can be suitably purified according to the present invention include γ- (n- or isoamyl) -γ-butyrolactone, γ- (n- or isohexyl) -γ-butyrolactone, γ- ( n- or isoheptyl) -γ-butyrolactone, γ- (n- or isooctyl) -γ-butyrolactone, γ- (n- or isononyl) -γ-butyrolactone and the like.
[0011]
Examples of the metal alkoxide used in the method of the present invention include alkali metal or alkaline earth metal alkoxides, and alkali metal alkoxides are particularly preferable. A metal alkoxide is obtained by making a metal and alcohol act, and can also use a commercial item. Of these, sodium methoxide or sodium ethoxide is easily available and preferred. These may be used in the form of powder, or may be used in the form of a methanol solution or an ethanol solution, respectively.
[0012]
The treatment in the purification method of the present invention is preferably carried out by adding a metal alkoxide to the above-mentioned γ-alkyl-γ-lactone to be treated, followed by mixing and stirring at a desired temperature, followed by distillation. The amount of the metal alkoxide is preferably 0.01 to 10% by weight, particularly preferably 0.1 to 1% by weight, based on the weight of the γ-alkyl-γ-lactone to be treated. The mixing temperature and time are not particularly limited, but the temperature is preferably from 80 to 180 ° C, particularly preferably from 100 to 150 ° C, and the time is preferably from 0.1 to 24 hours, particularly preferably from 0.5 to 2 hours. Subsequent distillation, preferably precision distillation, yields high-quality γ-alkyl-γ-lactones that can be used as fragrances, especially food additives, and have no flavor or acidity reminiscent of plastic. It is done.
[0013]
【Example】
EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in more detail, this invention is not limited to these.
[0014]
Reference example 1
Put 2,000 g of n-octanol (purity 98%, 15.0 mol) in an autoclave, heat and hold at 175 ° C, and stir it, while adding 245 g of hydrous acrylic acid (purity 80%, 2.7 mol) and di-tert-butyl peroxide A solution of 39.5 g (0.27 mol) of the mixture in 350 g (2.5 mol) of octanol was injected over 6 hours. The reaction was carried out for another hour at the same temperature. After completion of the reaction, unreacted n-octanol was distilled off from the reaction solution, followed by distillation under reduced pressure to obtain 395 g (2.15 mol, yield 80%) of γ- (n-heptyl) -γ-butyrolactone.
[0015]
Reference example 2
Add 1410 g of n-hexanol (purity 99%, 13.5 mol) to the autoclave, heat and hold at 170 ° C, and stir it, 270 g of hydrous acrylic acid (purity 80%, 3.0 mol) and di-tert-butyl peroxide A solution prepared by dissolving 44 g (0.3 mol) of the mixture in 580 g (5.5 mol) of n-hexanol was injected over 6 hours. The reaction was further carried out for 1 hour at the same temperature. After completion of the reaction, unreacted n-hexanol was distilled off from the reaction solution, followed by distillation under reduced pressure to obtain 355 g of γ- (n-pentyl) -γ-butyrolactone (2.25 mol, yield 76%).
[0016]
Example 1
100 g of γ- (n-heptyl) -γ-butyrolactone obtained in Reference Example 1 and 1.5 g of a 30% sodium methoxide methanol solution were mixed at 80 ° C. for 30 minutes, and then 0.67 kPa, 150 by a 20-stage precision distiller. Distilled under reduced pressure at ° C. As a result, γ- (n-heptyl) -γ-butyrolactone obtained in a yield of 90% has a sour and fruity flavor, and has good quality as a fragrance, particularly as a food additive. there were.
[0017]
Example 2
100 g of γ- (n-pentyl) -γ-butyrolactone obtained in Reference Example 2 and 1.0 g of 20% sodium ethoxide ethanol solution were mixed at 140 ° C. for 1 hour, and then 0.67 kPa, 130 using a 20-stage precision distiller. Distilled under reduced pressure at ° C. As a result, γ- (n-pentyl) -γ-butyrolactone obtained in a yield of 84% has an excellent coconut-like flavor with no plastic-like flavor or acidity, and is particularly useful as a fragrance. Good quality as an additive.
[0018]
Comparative Example 1
In Example 1, precision distillation was performed in the same manner except that the treatment with sodium methoxide was not performed. As a result, the yield of γ- (n-heptyl) -γ-butyrolactone with good quality was 50%.
[0019]
Comparative Example 2
In Example 2, precision distillation was performed in the same manner except that the treatment with sodium ethoxide was not performed. As a result, the yield of γ- (n-pentyl) -γ-butyrolactone having good quality was 40%.
[0020]
【The invention's effect】
According to the purification method of the present invention, γ-alkyl-γ-lactone, which has conventionally been difficult to purify in a high yield to a sufficient degree as a perfume, particularly a food additive, can be efficiently purified. Quality γ-alkyl-γ-lactone can be obtained in high yield.

Claims (3)

A method for purifying γ-alkyl-γ-lactone, comprising mixing and stirring a metal alkoxide with γ-alkyl-γ-lactone , followed by distillation . Metal alkoxide, a purification method according to claim 1, wherein those selected from sodium methoxide and sodium ethoxide. γ-alkyl-γ-lactone is obtained by heating and reacting acrylic acid and primary alcohol or secondary alcohol or a mixture thereof in the presence of ditertiary butyl peroxide. Item 3. A purification method according to item 1 or 2 .