JPS6033434B2 - Method for producing ε-alkyl-ε-lactones - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel method for producing g-alkyl-g-lactones.

Go-alkyl-go-lactones are not only important as fragrance substances, but also can be derived into various compounds and are important compounds as intermediates in organic synthesis.

Several methods are known for producing -alkyl-go-lactones.

For example, there is a method of simply heat treating 6-hydroxy acid. [E.J., Van Natta, J. W.Hill
and W. Day. CarOtheR, J. Am. Che
m. S. C, 56, 455 (1934)] However, this method produces a large amount of unsaturated acids or polymeric substances, resulting in poor yields, and the following methods have been proposed as improved methods. That is, under large dilution with benzene, P
- This is a method in which 6-hydroxy acid is slowly added dropwise to cyclize using toluenesulfonic acid. [0. Irde
m, V. Buddha m rti, w. T. Weller and
A. P. De. Jon Hoko, RECUEIL 8048
1 (1967)] However, even with this method, the yield is 4
It is 0 to 50%, which is not satisfactory, and there is a problem in that the reaction must be carried out for a long time under large dilution of benzene. Another method is to oxidize 2-alkyl-substituted cyclohexanone with persulfuric acid.
However, this method has many problems in terms of pollution and uses an oxidation reaction that is said to be insufficient in terms of yield. In addition, the production of the raw material, 2-alkyl-substituted cyclohexanone, is difficult and expensive. There is also the problem of becoming a thing.

As described above, each method still has many problems and cannot be said to be an industrially advantageous method. As a result of intensive research to establish a new synthesis method that can solve the above problems, the present inventors found that 6
-Alkyl-lactones can be obtained very easily by heating hydroxy acid esters, 6-hydroxy acids, or polymers thereof under reduced pressure in the presence of lead, tin, aluminum, titanium, or metal compounds thereof. This discovery led to the present invention.

That is, the present invention is characterized by ring-closing a 6-hydroxy acid ester, a 6-hydroxy acid, or a polymer thereof by heating under reduced pressure in the presence of a metal catalyst.

The 6-hydroxy acid ester or 6-hydroxy acid used as a starting material in the present invention is prepared by oxidation with Caro's acid [G. Lardell
i, V. Lambeni, W. T. Wellerand
A. P. De Jon hoko. RECUEIL 86,
481 (1967>), or oxidation with peracetic acid [Uk
r. Tsumugi im. Germany. 4 Mochi 1) 763 (1980)].

Furthermore, it can also be obtained by a method previously proposed by the present inventors, in which allyl acetate and a primary alcohol are heated in the presence of a radical initiator. Among these, the method of heating allyl acetate and primary alcohol in the presence of a radical initiator is more preferred. The details of the method for producing the 6-hydroxy acid ester that was previously filed by the present inventors will be described.

The reaction for synthesizing the 6-hydroxy acid ester described above can be considered as follows. In other words, in the reaction between the radical generated by the radical initiator and the alcohol, the hydrogen atom at the Q position of the alcohol is extracted and a new radical is generated, and this radical is added to the double bond of allyl acetate and reacts. It is thought that this will progress. 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 ester used can also be obtained by the reaction of allyl halide and malonate ester, but it can be obtained more cheaply as a creation product during the production of sebacate gester by the Kolbe electrolytic reaction of adipic acid monoester. .

As the allyl acetate, esters of lower alcohols having 1 to 8 carbon atoms, such as methyl allyl acetate, ethyl allyl acetate, isopropyl allyl acetate, etc. are used.
Methyl allylacetate is most preferred as it is industrially easily available. The primary alcohol used is
These are chain alcohols such as n-butyl alcohol, n-amyl alcohol, n-hexyl alcohol, and n-heptyl alcohol, and branched alcohols thereof.

Regarding the amount of these alcohols to be used, it is possible to obtain 6-hydroxy acid ester by using at least twice the mole per mole of allylic acetate. However, from the viewpoint of yield, it is preferable to use alcohol in an amount of 1 sonic mole or more, more preferably 2 sonic moles or more, based on the allylic acetate.
Moreover, even if too much alcohol is used, it is necessary to recover the alcohol by distillation after the reaction, and generally, 15 sonic moles or less is sufficient. Examples of the radical initiator used 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. Among them, ditertiary butyl peroxide is most preferred from the viewpoint of yield and stability. Further, the amount of the radical initiator used is 0.000.
05-1. The amount is 0.05 to 0.3 mol, preferably 0.05 to 0.3 mol. If the amount is less than 0.03 somole, 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. Moreover, if it is used in an amount exceeding 1.0 times the mole, not only is the peroxide wasted since no improvement in reaction yield can be expected, but also the amount of by-products resulting from the alcohol increases, which is not preferable. The reaction is preferably carried out at a temperature higher than the decomposition temperature of the radical initiator while decomposing the radical initiator. When using ditertiary butyl peroxide as a radical initiator, 140 to 200oo
It is preferable to carry out the reaction in a temperature range of . At temperatures lower than 140°C, the yield becomes extremely poor, and even at temperatures above 200°C, the yield becomes low.

Furthermore, the most preferable temperature range in terms of yield is 150 to 180 qo.
The reaction is generally carried out within this temperature range. Further, depending on the alcohol used, the reaction may be carried out under pressure in an autoclave due to its boiling point, but it can be carried out without any problem. During the reaction, allyl acetate, alcohol and radical initiator may be initially placed in a reactor at the same time to carry out the reaction.

Alternatively, the reaction may be carried out by first putting a portion into the reactor and then dropping the portion dropwise. That is, aryl acetate and alcohol may be initially placed in a reactor, and the reaction may be carried out while dropping a solution of the radical initiator and alcohol;
A solution containing allyl acetate, alcohol, and a radical initiator may also be added dropwise. In addition, the reaction is generally 2 to 1
It is better to do it during feeding time. If the reaction time is too short, allyl acetate from the reaction may remain, and if the reaction time is too long, there is no point. As explained above, 6-hydroxy acid esters can be obtained industrially very advantageously, and have the following advantages.

First, the reaction process is simplified at once, making it possible to produce the product 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 sebacate gester from adipic acid monoester, and all of them are easily available industrially. As the metal catalyst used in the reaction of the present invention, metals or metal compounds commonly used as polyester depolymerization catalysts can be used.

For example, alkali metals or their chlorides, carbonates,
Nitrates, alkoxides, alkali metals or their chlorides, carbonates, nitrates, alkoxides, magnesium, cadmium, iron, cobalt, tin, Kanaya, zinc or their oxides, chlorides, carbonates, nitrates, hydroxides Examples include metals, organic acid salts, alkyl metal compounds, titanium, aluminum, and alkoxides thereof. Among these, lead, tin, titanium,
Aluminum or metal compounds thereof are preferred. These metal catalysts may be used alone or in combination. The amount of these metal catalysts to be used is not particularly limited, but is 0.1 to 10% by weight, preferably 0.5 to 5% by weight, based on the starting material of 6-hydroxy acid ester, 6-hydroxy acid or polymer thereof. % by weight. If the amount exceeds 1% by weight, there is almost no effect by increasing the amount, and if too much is added, the yield will deteriorate.

At an amount of 0.1% by weight, the addition has almost no effect. The production method of the present invention can be obtained by directly adding a metal catalyst to a 6-hydroxy acid ester or a 6-hydroxy acid, heating it under reduced pressure, closing it, and distilling off the go-alkyl-go-fuchtone.

Of course, in the case of 6-hydroxy acid ester, 6-hydroxy acid ester may be distilled out at the same time as the go-alkyl-go-lactone, but the 6-hydroxy acid ester may be distilled out at the same time as the go-alkyl-do-lactone. It is also possible to separate the produced go-alkyl-do-lactone and the raw material 6-hydroxy acid ester using a crab and continue the reaction while only the go-alkyl-do-lactone is extracted from the crab.
Alternatively, 6-hydroxy acid ester or 6-hydroxy acid is heated under reduced pressure to distill off methanol or water to produce a polymer thereof, and then a metal catalyst is added and heated under reduced pressure to produce a product. Certain go-alkyl-go-lactones can also be obtained by extraction. Of course, there is no problem in producing a 6-hydroxy acid ester or a 6-hydroxy acid polymer by adding a metal catalyst from the beginning. Once the method passes through a polymer, the phenomenon that the 6-hydroxy acid ester is distilled out at the same time as the product g-alkyl-g-lactone does not occur. Further, in the production method of the present invention, it is also possible to use a high boiling point inert solvent as the reaction medium. In the production method of the present invention, the reaction can be carried out at a reduced pressure of 5 Hg or more, but it is usually carried out at a reduced pressure of about 1 to 2 Hg. Of course, there is nothing wrong with doing it in a higher vacuum. Furthermore, the manufacturing method of the present invention includes:
It is carried out under the above-mentioned reduced pressure and heated to a temperature of 150 to 350°C, preferably in a temperature range of 180 to 280°C. At a temperature below 150 qo, the reaction rate is slow and the reaction substantially does not proceed even at a high degree of vacuum.

At temperatures above 350 qC, side reactions occur and the yield deteriorates.

Although the production method of the present invention is usually carried out in the absence of a reaction medium, it is of course possible to carry out the process using a high-boiling inert solvent as the reaction medium.

The use of a reaction medium has the effect of facilitating heating and making heating uniform, and saturated hydrocarbons such as high boiling point liquid paraffin and solid paraffin are usually effective as the high boiling point inert solvent. Further, the amount of the high boiling point inert solvent used may generally be less than 2 pm of the starting material. The crude product distilled by the production method of the present invention has good purity and is extremely easy to purify.

That is, a highly pure target product can be easily obtained simply by distillation purification. As detailed above, conventional methods use inefficient reaction operations and reaction operations that are problematic in terms of pollution.
Moreover, the yield was not satisfactory,
In the method of the present invention, it is possible to obtain g-alkyl-lactones in extremely high yields through extremely easy reaction operations.

In particular, when using a 6-hydroxy acid ester or 6-hydroxy acid obtained by combining allylacetic acid ester and a primary or secondary alcohol in the presence of a radical initiator as the starting material, it is much more effective than the conventional method. This is advantageous and allows the desired alkyl-lactone to be produced even more advantageously. EXAMPLES 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 2 Put 25 kg (2.84 mol) of n-amyl alcohol into the autoclave and bring the internal temperature to 1550 while praying with a candle.
I set it to 0.

A mixture of 25 moles of n-amyl alcohol (2 moles), methyl allyl acetate IQr (0.088 moles) and 2.0 moles of ditertiary butyl peroxide (0.014 moles) was made homogeneous, This mixed solution was introduced into an autoclave heated to 1590 quarts for 4 hours, and then heated to 155 qo for 2 hours.
I worshiped time. After the reaction was completed, the alcohol was removed and methyl 6-hydroxydecanoate was dissolved at 112-117°C (1 Hg) under reduced pressure7. I got a connection. Next, 0.1% of lead monoxide powder was added to 5.0% of methyl 6-hydroxydecanoate, stirred, and heated to 180 to 200°C under reduced pressure of 30% Hg.
The mixture was heated at a temperature of 2 hours. Then, under a reduced pressure of 1 to 2 side Hg, the mixture was heated at a temperature of 200 to 220 oo for 1 hour while distilling the product, and 3. Very crude do-n-butyl-lactone was obtained. The purity of the distilled crude n-butyl-lactone was 98%, and the yield was % of the total. The purity of the crude n-butyl-go-lactone was analyzed by gas chromatography. (Purity was determined in the same manner in subsequent examples.) Example 2 2 250 ml of n-amyl alcohol (2.84 mol) was placed in the autoclave, and the internal temperature was raised to 160°C while bowing. .

A mixture of n-amyl alcohol 25 (2.0 moles), methyl allyl acetate (0.044 mole) and ditertiary butyl peroxide 0.78 (0.005 mole) was homogenized, and this The mixture was introduced into an autoclave heated to 1600 °C for 4 hours. Another 2 hours 160 after introduction
The reaction was terminated at ℃. After the reaction is completed, 6-
4. Methyl hydroxydecanoate. &Z got it. Then 6
-Methyl hydroxydecanoate 4. After adding 0.1 r of lead acetate trihydrate to the female r and stirring, the mixture was lit for 2 hours at a temperature of 180 to 200°C under a reduced pressure of 20 winds of Hg. then 8
The crude n-butyl ruby lactone was heated for 2 hours while distilling the product at a temperature of 240-260 pm under a reduced pressure of ~10 pig Hg. Got criticism. The purity of the distilled crude n-butyl-go-lactone was 96%, and the yield was 85%.
It was hot. Example 3 2 Add 50 Qr of n-amyl alcohol to the autoclave.
(0.5 mol) and methyl allyl acetate 80 g (0.07 mol)
mole) and ditertiary butyl peroxide 50 mole (0.03
4 mol) was added at the same time, the internal temperature was raised to 165°C, and the mixture was reacted for 4 hours with concentrated entrainment.

After the reaction is completed, methyl 6-hydroxydecanoate 7 is obtained by distillation.
．． I got 2r. Next, methyl 6-hydroxydecanoate5. Shout out to Titanium Tetra Primary Butoxide 0.1
After adding 8 and stirring, 200
Heated for 3 hours at a temperature of ~220°C. Then 1 to 2 lugs
3. Heating the product at a temperature of 200 to 23 mm under reduced pressure for 1 hour while allowing the product to evaporate; 3. Crude 1-n-butyloogolactone was obtained. The purity of the distilled crude n-butyl-go-lactone was 97%, and the yield was 89%.
Example 4 2 Put 25 parts (0.3 molar) of n-butyl alcohol into the autoclave, and remove 155 ml of inner stripes while pushing the fly.
I set it to 0.

n-butyl alcohol 25Qr (0.3 mol), methyl allyl acetate 10 mosquitoes (0.8 mol female) and ditertiary butyl peroxide 2. A mixture with Qr (0.014 mol) was mixed uniformly, and this mixture was introduced into an autoclave heated to 155°C for 4 hours, and after the introduction, the mixture was heated at 155°C for an additional 2 hours. 7. Methyl 6-hydroxynonanoate is extracted from the reaction starch by distillation. I got it. Then methyl 6-hydroxynonanoate5. After adding 0.058 dibutyltin dilaurate to the female R and stirring, the mixture was heated at a temperature of 180 to 200 qC for 3 hours under a reduced pressure of 20 ship Hg. Next, the product was heated for 4 hours under a reduced pressure of 3 to 5 feet of Hg at a temperature of 220 to 250 hours to obtain 3.6 grams of crude n-propyl-lactone. The purity of the crab-removed lees-n-propyl-lactone is 96%,
The yield was 83%. Example 5 2 N-amyl alcohol 300 feed (2.59 mol) was placed in the autoclave, and the internal temperature was brought to 160:00 pm while the autoclave was lit.

n-heptyl alcohol 30 r (2.59 mol), methyl allyl acetate 108 (0. mol) and ditertiary butyl peroxide 2. The mixture with Qr (0.014 mol) was made homogeneous, and this mixed liquid was introduced into an autoclave heated to 160° C. for 4 hours, and after the introduction, the mixture was further heated at 160 qo for 2 hours. From the reaction solution, 10.5% of methyl 6-hydroxydodecanoate was obtained by distillation. Next, 0.1 g of tert-butoxyaluminum was added to 5.0 g of methyl 6-hydroxydodecanoate, stirred, and heated at a temperature of 180 to 20,000 for 3 hours under a reduced pressure of 30,000 Hg. Then under reduced pressure of 1-2 side Hg, 200-230
Heating for 2 hours while distilling the product at a temperature of 3.
．． 5 crude n-hexyl-golactone was obtained. The purity of the distilled crude n-hexyl-lactone is 97.
%, and the yield was 79%. Example 6 2 Add 50 ml of amyl alcohol to the autoclave.
(0.5 total mole) and ethyl allyl acetate 9.08 (0.0
7 mol) and ditertiary butyl peroxide5. Melon y (0.
0 mol) at the same time, and the internal temperature was raised to 160°C, and the reaction was allowed to proceed for 4 hours while keeping the temperature at 160°C.

After the reaction is completed, ethyl 6-hydroxydecanoate 6 is obtained by distillation.
．． I got pine r. Then ethyl 6-hydroxydecanoate 5
．． Qr and 0.1 lead zinc oxide powder feed were mixed and heated at a temperature of 180 to 200 oo for 2 hours under a reduced pressure of 20 pig Hg.
The product was then heated for 1 hour under a reduced pressure of 1 to 2 Hg at a temperature of 200 to 0.0 Hg to obtain 3.78 crude do-n-butyl-butyl-lactone. Distilled crude product-n
The purity of -butyl-goractone is 1%, and the yield is 8%.
It was 6%. Example 7 Methyl 6-hydroxydecanoate was obtained in the same manner as in Example 1, and was hydrolyzed by a conventional method to obtain 6-hydroxydecanoic acid.

Mix 5.08 g of 6-hydroxydecanoic acid and 0.1 gr of titanium tetra secondary propoxide,
The product was heated for 5 hours under a reduced pressure of 250 to 280 oo to obtain 3.2 r of crude go-n-butyl-go-lactone.

Claims (1)

[Claims] 1. A process characterized by ring-closing a 6-hydroxy acid ester, a 6-hydroxy acid, or a polymer thereof by heating it under reduced pressure in the presence of lead, tin, aluminum, titanium, or a metal compound thereof. Method for producing ε-alkyl-ε-lactones. 2. The amount of lead, tin, aluminum, titanium, or their metal compounds is 6-hydroxy acid ester, 6-
2. The method according to claim 1, wherein the amount is 0.1 to 10% by weight based on the hydroxy acid or its polymer. 3. The method according to claim 1, characterized in that the degree of pressure reduction is set to 50 mmHg or more, and the heating temperature is set to 150 to 350°C.