JPH0231068B2 - DERUTAARAKUTON NOSEIZOHO - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a highly productive method for producing δ-lactone, and more specifically, the present invention relates to a highly productive method for producing δ-lactone, and more specifically, 2-substituted cyclopentanone is oxidized with a peroxide in a lower carboxylic acid solvent to produce the corresponding δ-lactone. This invention relates to a method for increasing the yield of δ-lactone by adding acyloxycarboxylic acid to the reaction system when producing lactone.

Since δ-lactones such as δ-decalactone and δ-dodecalactone generally have a unique aroma, their importance has been increasingly recognized in recent years, mainly as flavoring agents for food additives. Conventionally, many methods for producing such δ-lactones are known, but an industrially important method is a method in which 2-substituted cyclopentanone is converted into the corresponding δ-lactone by Baeyer-Villiger reaction. At this time, lower carboxylic acids such as acetic acid and propionic acid are used as the reaction solvent, and organic or inorganic peroxides are used as the oxidizing agent, but usually the desired δ-
Along with the lactone, a considerable amount of high-boiling by-products are produced and δ
-Causes a decrease in lactone yield.

Therefore, the present inventors conducted intensive studies on methods for increasing the yield of δ-lactone, and found that the main component of the high-boiling byproduct is acyloxycarboxylic acid, which is produced by solvolysis of δ-lactone. Focusing on the fact that there is an equilibrium relationship with δ-lactone in the reaction system, we discovered that adding this acyloxycarboxylic acid to the reaction system is extremely effective in increasing the yield of δ-lactone, and completed the present invention. I came to the conclusion.

That is, an object of the present invention is to efficiently increase the yield of δ-lactone with simple operations when producing δ-lactone by Bayer-Villiger reaction. This can be achieved by adding by-product acyloxycarboxylic acid to the reaction system when δ-lactone is produced by oxidation with a peroxide in a solvent.

The 2-substituted cyclopentanone to be subjected to the Bayer-Villiger reaction in the present invention may be any one having a saturated hydrocarbon residue as a substituent, such as a linear or branched alkyl group or a cycloalkyl group. As a concrete example, 2-
Ethylcyclopentanone, 2-isopropylcyclopentanone, 2-n-butylcyclopentanone, 2-isobutylcyclopentanone, 2-n-
Pentylcyclopentanone, 2-n-hexylcyclopentanone, 2-n-heptylcyclopentanone, 2-n-octylcyclopentanone, 2-
(2'-ethylhexyl)cyclopentanone, 2-
Examples include n-nonylcyclopentanone, 2-cyclopentylcyclopentanone, and 2-cyclohexylcyclopentanone.

Also, the alkyl of 2-substituted cyclopentanone such as 3-methyl-2-n-butylcyclopentanone, 3-methyl-2-n-pentylcyclopentanone, 3-methyl-2-n-hexylcyclopentanone, etc. Derivatives can be similarly used as long as they do not essentially inhibit the Bayer-Villiger reaction. Among these compounds, 2-substituted cyclopentanone having an alkyl group having 2 to 11 carbon atoms is particularly preferred.

On the other hand, the peroxide used in the reaction may be any commonly used peroxide, and specific examples thereof include lower percarboxylic acids such as peracetic acid, perpropionic acid, and perbutyric acid. It is also possible to make hydrogen peroxide coexist with a mineral acid such as sulfuric acid, hydrochloric acid, or phosphoric acid in a lower carboxylic acid used as a solvent, and use the peracid generated in the system.

The Bayer-Villiger reaction in the present invention is 2-
It is carried out by oxidizing a substituted cyclopentanone with a peroxide in a lower carboxylic acid solvent such as acetic acid, propionic acid, butyric acid, etc. in the presence of a by-product acyloxycarboxylic acid.

The by-product acyloxycarboxylic acid used is produced by the solvolysis of δ-lactone according to the reaction formula below, and after removing low-boiling substances mainly composed of δ-lactone from the Bayer-Villiger reaction solution, it is converted to high-boiling point substances. It can be easily separated and recovered as a fraction. In this case, it may be recovered as a distillate fraction, or conversely as a distillation residue, or it may be newly added from outside the system.

(In the formula, R ₁ represents a hydrocarbon residue and R ₂ represents a lower alkyl group.) The above formula is written without substituents at the α-, β-, and γ-positions. However, when there are substituents at these positions, corresponding acyloxycarboxylic acids are produced as a by-product according to a reaction formula similar to the above formula, and such by-product acyloxycarboxylic acids are also included in the present invention. .

Although there is no particular restriction on the timing of addition of the acyloxycarboxylic acid, it is usually added to the reaction system before the Baeyer-Villiger reaction. The amount of the acyloxycarboxylic acid to be used may be selected as appropriate, but is usually 0.05 to 5 times the weight of the 2-substituted cyclopentanone used in the reaction, preferably 0.1 to 3 times the weight.

Other reaction conditions may be carried out according to conventional methods, and usually 0.8 to 2
Using 0.5 to 10 times the weight of lower carboxylic acid per mole of peroxide and 2-substituted cyclopentanone,
Performed at ~80°C for 0.5-30 hours. In this case, the reaction system may be under reduced pressure or increased pressure, and either a batch method or a continuous method may be adopted, but the reaction is usually carried out using a stirred reactor under normal pressure and heating. method is adopted.

After the reaction solution obtained in this way is subjected to appropriate treatments such as washing, extraction, and drying according to conventional methods,
The desired δ-lactone can be obtained by distillation. At this time, acyloxycarboxylic acid is usually produced as a by-product in an amount of 0.05 to 5 times the weight of δ-lactone, but according to the present invention, this by-product can be used in the next Baeyer-Villiger reaction. Thereby, the yield of δ-lactone can be increased, and as a result, the reaction yield of the Bayer-Villiger reaction can be dramatically improved. Furthermore, by recycling by-products, it is possible to reduce the amount of waste discharged outside the system, which is a great advantage in terms of the process.

The present invention will be explained in more detail with reference to Examples below. Note that parts in the examples are based on weight.

Example 1 154 parts of 2-n-pentylcyclopentanone, 277 parts of glacial acetic acid, 31 parts of water, and 5-acetoxydecanoic acid
58 parts were placed in a glass reactor equipped with a stirrer and a reflux condenser, heated in a hot water bath until the internal temperature reached 45°C, then 6.2 parts of concentrated sulfuric acid was added, followed by 136 parts of 35% hydrogen peroxide. The solution was added dropwise over 1.5 hours while adjusting the internal temperature to 45-50°C.

After further reaction at 50℃ for 6 hours, water
After adding 385 parts of toluene and 385 parts of toluene and allowing it to stand still, the obtained oil layer was further washed with water and distilled under reduced pressure.
-148.1 parts of Decalactone were obtained. In addition, 3.1 parts of unreacted 2-n-pentylcyclopentanone was recovered, and 82.8 parts of a residue containing 5-acetoxydecanoic acid as a main component were obtained.

In addition, in an experiment under the same conditions except that 5-acetoxydecanoic acid was not added, δ
- 128 parts of decalactone, 3.1 parts of unreacted 2-n-pentylcyclopentanone, and 58.0 parts of residue mainly composed of 5-acetoxydecanoic acid were obtained. It was found that the addition of raw acylcarboxylic acid resulted in an increase of 15.7%.

Example 2 The reaction and post-treatment were carried out in the same manner as in Example 1 except that the amount of 5-acetoxydecanoic acid used in Example 1 was changed to 116 parts. As a result, δ-
The yield of decalactone was 163.4 parts, compared to 27.7 parts when 5-acetoxydecanoic acid was not added.
% yield increase.

Example 3 The reaction and post-treatment were carried out in the same manner as in Example 1, except that 182 parts of 2-n-heptylcyclopentanone was used as the starting material and 46 parts of 5-acetoxydodecanoic acid was used as the by-product acyloxycarboxylic acid. I went. As a result, the yield of δ-dodecalactone increased by 17.1% compared to the case where 5-acetoxydodecanoic acid was not added.

Example 4 The reaction and post-treatment were carried out in the same manner as in Example 1, except that 82.8 parts of the distillation residue obtained in Example 1 and containing 5-acetoxydecanoic acid as a main component was used. As a result, 154 parts of δ-decalactone was obtained,
3.5 parts of unreacted 2-n-pentylcyclopentanone was recovered. The yield of δ-decalactone increased by 20.3% compared to the case where no distillation residue was added.

Claims (1)

[Scope of Claims] 1. When producing the corresponding δ-lactone by oxidizing 2-substituted cyclopentanone with a peroxide in a lower carboxylic acid solvent, the by-product acyloxycarboxylic acid is not added to the reaction system. Featured δ
-Lactone production method. 2. The method according to claim 1, wherein the acyloxycarboxylic acid is separated and recovered from the reaction system.