JPS6230978B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel method for producing 6-hydroxyalkanoic acid esters.

6-Hydroxyalkanoic acid ester is a highly reactive compound with two functional groups, and is an important compound as an intermediate for organic synthesis. In particular, lactonization can lead to γ-, δ-, or ξ-lactones, which are extremely important compounds as fragrances.

Conventionally, the following methods are known as methods for producing 6-hydroxyalkanoic acids. That is, cyclohexanone and aldehyde are reacted in the presence of an alkali, and then dehydrated with oxalic acid to form 2-
Alkylidenecyclopentanone is synthesized and then hydrogenated to obtain 2-alkylcyclopentanone, which is then oxidized with Caro's acid to obtain 6-hydroxyalkanoic acid. [G.Lardell.V.
Lamlerti, WT Weller, APDe Jonge,
RECUEIL, 86 , 481 (1967)] In addition, as an improvement to the above method, cyclohexanone and α-olefin were alkylated in the presence of phenyldimethylmethane hydroperoxide to synthesize 2-alkylcyclohexanone, and then peracetic acid A method has been proposed in which 6-hydroxyalkanoic acids are obtained by oxidation by [Ukr.Khim.Zh, 46 (7)763
(1980)] 6-hydroxyalkanoic acid ester can be easily obtained by esterifying this 6-hydroxyalkanoic acid.

However, the former conventional method not only has the problem of a long reaction process, but also uses aldehyde, which is generally considered to be expensive, as one of the raw materials, and the oxidation reaction with Caro's acid, which has many pollution problems. There is also the problem of using . In addition, although the improved method is a considerable improvement in that the reaction steps are halved, there is a problem in that expensive peracetic acid is used as an oxidizing agent in the oxidation of 2-alkylcyclohexanone. As described above, both methods still have many problems and cannot be said to be industrially advantageous production methods.

The present inventors conducted extensive research to establish a new synthesis method that could solve the above problems, and surprisingly, they succeeded in further developing the method by heating allyl acetate and alcohol in the presence of a radical initiator. The present inventors have discovered that 6-hydroxyalkanoic acid esters can be obtained all at once using the following methods, leading to the present invention.

That is, in the present invention, when reacting allyl acetate and a primary alcohol in the presence of a radical initiator, the primary alcohol is used at least twice in mole relative to the allyl acetate, and the reaction is carried out by heating. This is a characteristic feature.

The reaction of the present invention can be considered as follows.
In other words, the reaction between the radical generated by the radical initiator and the alcohol causes the hydrogen atom at the alpha position of the alcohol to be extracted and a new radical to be generated.
It is thought that the reaction proceeds by adding this radical to the double bond of allyl acetate. This reaction is considered to be a type of radical addition reaction to double bonds, and the reaction is thought to proceed according to the mechanism of a radical chain reaction.

The allyl acetate used in the present invention can also be obtained by the reaction of allyl halide and malonic acid ester, but it is cheaper to obtain it as a by-product of the production of sebacic acid diester by the Kolbe electrolytic reaction of adipic acid monoester. can be obtained as Allyl acetate has 1 to 8 carbon atoms.
Lower alcohol esters such as methyl allyl acetate, ethyl allyl acetate, isopropyl allyl acetate, etc. are used, but methyl allyl acetate is most preferred as it is industrially easily available.

The primary alcohol used in the present invention includes chain alcohols such as n-butyl alcohol, n-amyl alcohol, n-hexyl alcohol, and n-heptyl alcohol, and branched alcohols thereof. As for the amount of these alcohols used, of course, 6-hydroxyalkanoic acid ester can be obtained by using two or more moles or more per mole of allyl acetic ester. However, in terms of yield, 10
It is preferable to use alcohol in a molar amount or more, more preferably 20 times or more in molar amount. Furthermore, even if too much alcohol is used, it is necessary to recover the alcohol by distillation after the reaction, and generally 150 times the mole or less is sufficient.

The radical initiator used in the present invention includes:
Examples include organic peroxides such as benzoyl peroxide and ditertiary butyl peroxide, organic hydroperoxides, azo compounds, and many other compounds generally known as radical polymerization initiators, but yield and stability are limited. From the viewpoint of properties, ditertiary butyl peroxide is most preferred. The amount of the radical initiator used is 0.05 to 1.0 times, preferably 0.05 to 0.5 times, per mole of allyl acetate. If the amount is less than 0.05 times the mole, the reaction yield will be poor, which is not preferable. This is particularly noticeable when the amount of alcohol is small relative to allyl acetate. Furthermore, if it is used in an amount greater than 1.0 times the mole, not only is peroxide wasted as no improvement in reaction yield can be expected, but also by-products resulting from the alcohol increase, which is not preferable.

The present invention is preferably carried out while decomposing the radical initiator at a temperature higher than the decomposition temperature of the radical initiator. When ditertiary butyl peroxide is used as a radical initiator, it is preferable to carry out the reaction in a temperature range of 140 to 200°C. At temperatures lower than 140°C, the yield becomes extremely poor, and at temperatures above 200°C, the yield also becomes low. Further, the most preferable temperature range in terms of yield is 150 to 180°C, and the reaction is generally carried out within this temperature range. Also, depending on the alcohol used, the reaction may be carried out under pressure in an autoclave due to its boiling point.
It can be done without any problem.

In the present invention, allyl acetate, alcohol, and radical initiator may be initially placed in a reactor at the same time to carry out the reaction. Alternatively, allyl acetate and alcohol may be initially placed in a reactor, and the reaction may be carried out while dropping a radical initiator and alcohol solution; alternatively, only alcohol may be initially placed in the reactor, and allyl acetate Alternatively, a liquid containing alcohol and a radical initiator may be dropped. Further, the reaction may generally be carried out for 2 to 10 hours. If the reaction time is too short, unreacted allyl acetate may remain, and if the reaction time is too long, there is no point.

As detailed above, the present invention is a novel method for producing 6-hydroxyalkanoic acid esters, which is industrially extremely advantageous compared to conventional production methods, and the method of the present invention has the following advantages.

First, the reaction process has been simplified at once. Conventionally, it required four or two steps, but now it can be produced in one step, and the reaction itself can be performed relatively easily. Second, the raw materials used are inexpensive. Not to mention various alcohols, allyl acetate can also be obtained as a by-product during the electrolytic production of sebacic acid diester from adipic acid monoester, and all of them are easily available industrially.

Next, the present invention will be explained in more detail with reference to Examples, but it goes without saying that the present invention is not limited thereto.

Example 1 Add n-amyl alcohol to a 2l autoclave.
Add 250gr (2.84mol) and bring the internal temperature to 155 while stirring.
It was set to ℃. A mixture of 250gr (2.8mol) of n-amyl alcohol, 10gr (0.088mol) of methyl allylacetate, and 2.0gr (0.014mol) of ditertiary butyl peroxide was homogenized, and the mixture was heated to 155°C and stirred in an autoclave. After the introduction, the solution was stirred at 155°C for 2 hours. After the reaction is complete, the alcohol is distilled off and the temperature is reduced to 112-117℃ (1mmHg).
7.9 gr of methyl 6-hydroxydecanoate was obtained.
The isolated yield was 45% based on methyl allylacetate. (All yields in subsequent examples are based on methyl allylacetate.) Example 2 25g (0.284 mol) of n-amyl alcohol was placed in a 200ml autoclave, and the internal temperature was raised to 160°C while stirring. . n-amyl alcohol 25gr
(0.284 mol) and methyl allylacetate 0.5 gr (0.0044 mol) and ditertiary butyl peroxide 0.07 gr
(0.0005 mol) was made homogeneous, and this mixture was heated to 160℃ and placed in an autoclave with stirring for
introduced in time. After the introduction, the mixture was further stirred at 160°C for 2 hours to complete the reaction. Methyl 6-hydroxydecanoate contained in the reaction solution was determined by gas chromatography. The yield was 51%.

Example 3 25 gr (0.284 mol) of n-amyl alcohol was placed in a 200 ml autoclave, and the internal temperature was raised to 160° C. while stirring. n-amyl alcohol 25gr
(0.284 mol), 2.5 gr (0.022 mol) of methyl allylacetate, and 0.5 gr (0.0034 mol) of di-tert-butyl peroxide.
160 mole) and make the mixture homogeneous.
The mixture was introduced into an autoclave heated and stirred at ℃ for 6 hours. After the introduction, the mixture was further stirred at 160°C for 2 hours to complete the reaction. Methyl 6-hydroxydecanoate contained in the reaction solution was determined by gas chromatography. The yield was 40%.

Example 4 50gr (0.568mol) of n-amyl alcohol and 0.8gr methyl allyl acetate in a 200ml autoclave
(0.007 mol) and ditertiary butyl peroxide
0.5gr (0.0034mol) was added at the same time, and the internal temperature was raised to 165°C while stirring, and the reaction was allowed to proceed for 4 hours. After the reaction was completed, methyl 6-hydroxydecanoate contained in the reaction solution was determined by gas chromatography. The yield was 52%.

Example 5 50gr (0.568mol) of n-amyl alcohol and 5gr methyl allyl acetate in a 200ml autoclave
(0.044 mol) and 1gr ditertiary butyl peroxide
(0.0069 mol) were added at the same time, and while stirring, the internal temperature was raised to 150°C and the reaction was allowed to proceed for 8 hours. After the reaction was completed, methyl 6-hydroxydecanoate contained in the reaction solution was determined by gas chromatography. The yield was 15%.

Example 6 25 gr (0.338 mol) of n-butyl alcohol was placed in a 200 ml autoclave, and the internal temperature was brought to 155° C. while stirring. n-butyl alcohol 25gr
(0.338 mol) and methyl allylacetate 1 gr (0.0088 mol) and ditertiary butyl peroxide 0.2 gr
(0.0014 mol) was made homogeneous, and this mixture was heated to 155℃ and placed in an autoclave with stirring for
After the introduction, the mixture was further stirred at 155°C for 2 hours to complete the reaction. Methyl 6-hydroxynonanoate contained in the reaction solution was determined by gas chromatography. The yield was 47%.

Example 7 30g (0.259mol) of n-heptyl alcohol was placed in a 200ml autoclave, and the internal temperature was brought to 160°C while stirring. n-heptyl alcohol 30gr
(0.259 mol) and methyl allylacetate 1 gr (0.0088 mol) and ditertiary butyl peroxide 0.2 gr
(0.0014 mol) was made homogeneous, and this mixture was heated to 160°C and placed in an autoclave with stirring.
After the introduction, the mixture was further stirred at 160°C for 2 hours to complete the reaction. Methyl 6-hydroxydodecanoate contained in the reaction solution was determined by gas chromatography. The yield was 51%.

Example 8 44gr (0.5mol) of n-amyl alcohol and 23gr methyl allyl acetate in a 200ml four-necked flask.
(0.20 mol) and while heating under reflux, a mixed solution of 44 gr (0.5 mol) of n-amyl alcohol and 2.9 gr (0.02 mol) of ditertiary butyl peroxide was added dropwise over 6 hours. After the mixture was added dropwise, heating under reflux was continued for another 2 hours to complete the reaction. Methyl 6-hydroxydecanoate contained in the reaction solution was determined by gas chromatography. The yield was 3%.

Example 9 50gr (0.568mol) of n-amyl alcohol and 0.9gr ethyl allyl acetate in a 200ml autoclave
(0.007 mol) and ditertiary butyl peroxide
0.5gr (0.0034mol) was added at the same time, and the internal temperature was raised to 160°C while stirring for 4 hours to react. After the reaction was completed, the amount of ethyl 6-hydroxydecanoate contained in the reaction solution was determined by gas chromatography. The yield was 48%.

Claims (1)

[Claims] 1. When reacting allyl acetate and primary alcohol in the presence of a radical initiator, the primary alcohol is used at least twice the mole of allyl acetate, and the reaction is carried out by heating. A method for producing a 6-hydroxyalkanoic acid ester, characterized by: 2. The method according to claim 1, wherein the primary alcohol is used at least 10 times the mole of allyl acetate. 3. The method according to claim 1, wherein the primary alcohol is used at least 20 times the mole of allyl acetate. 4. The method according to claim 1, wherein the radical initiator is used in an amount of 0.05 to 1.0 times the mole of allyl acetate. 5. The method according to claim 1, wherein the radical initiator is ditertiary butyl peroxide. 6. The method according to claim 1, wherein the radical initiator is ditertiary butyl peroxide and the heating is carried out at a temperature in the range of 140 to 200°C.