JPH0225476A - Improved production of substituted franone - Google Patents

Abstract

PURPOSE: To easily obtain the title compd. useful for perfume in high yield by reacting epoxide corresponding to the objective compd. and a β-diketo compd. in the presence of an aq. base at specific temp. and making the reaction mixture acidic to recover a product.

CONSTITUTION: A compd. represented by formula I (wherein R and R₁ are H or 1-8C alkyl and, pref., R₁ is H and R is 1-8C, especially, 1-4C alkyl) and a compd. represented by formula II [wherein R₂ is R'₂ or OR'₂ (wherein R'₂ is a 1-20C hydrocarbon group), pref., 1-4C alkyl, especially CH₃ and X is an elimination group, pref., 1-12C, especially, 4-10C alkoxy] are reacted in a mol. ratio I:II=1:1-3, pref., 1:1.1-1.7 in the presence of an aq.soln. of an aq. base, pref., NaOH or KOH while a reaction mixture is held to temp. of 40°C or lower. Subsequently, the reaction mixture is made acidic pref. by a mineral acid, especially, hydrochloric acid to be adjusted to pH 4-7 to accelerate phase separation and, thereafter, an aq. phase is separated from an org. phase to recover a product to advantageously obtain the objective compd. represented by formula III.

COPYRIGHT: (C)1990,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides an improved method for producing lactones, particularly those of the formula:
8 represents hydrogen or alkyl, and R2 represents a hydrocarbon group or -0-hydrocarbon group).

Johnson, U.S. Pat. No. 2,4,33,827, discloses a process in which ethylene oxide is reacted with ethyl acetoacetate in an ethanolic solution of an alkali metal hydroxide for 48 hours at a temperature of 0" to -5°C, followed by extraction. This book describes a method for producing alpha-acetyl-gamma-butyrolactone [3-acetyldihydro-2(3H)-furanone] by fractionating and recovering alpha-acetyl-gamma-butyrolactone.The desired lactone yield is said to be about 60%. This method also has the disadvantage of requiring operation below 0° C. for at least 48 hours.

In consideration of long-term reactions at temperatures below 0°C, Canadian patent 1s46. of LCLQmf et al. No. s73 is C"4-6 tertiary alkanol acetoacetate and epoxide 110'
describes a process for the production of alpha-aceto-gamma-lactone by reaction at temperatures from 0 to +10 °C.Temperatures from 0 to +3 °C are preferred.Lac et al. The reaction is carried out either by producing a sodium derivative of acetate and then adding epoxide to it.

It would be highly advantageous if the reaction could be carried out in a short time even at high temperatures and at the same time increase the yield of lactone product considerably. These advantages are easily achieved by the improved method of the present invention.

The present invention relates to a method for producing substituted furanones according to the following reaction formula.

In the above formula, R, R, and R2 are as defined above and X is a leaving group. The reaction is preferably carried out in an aqueous solution of sodium or potassium hydroxide. Furanone derivatives produced by this method have a very pleasant odor and are useful for perfume applications. A particularly convenient embodiment in which good yields of the substituted furanones of the present invention are obtained is to add base and water to the mixture of epoxide and beta-diketo compound at a rate such that the temperature of the mixture does not exceed 40°C. After the reaction is essentially complete, the mixture is acidified and the organic phase is separated from which the substituted furanone product is recovered. It is particularly convenient if the epoxide is a 1,2-epoxyalkane and the beta diketo compound is a beta-keto ester in which the ester moiety is derived from an aliphatic alcohol having 4 to 10 carbon atoms.

The present invention relates to a new process for the preparation of substituted furanones having the formula: oxide and the formula: In the above formula, R and R1 represent hydrogen or C,8 alkyl, and R1
represents a Cl-20 hydrocarbon group or a 10-hydrocarbon group having 1 to 20 carbon atoms. Suitable 10-hydrocarbon groups include alkoxy, cycloalkoxy and aryloxy groups.

Preferred R1 have 1 to 12 longitudinal atoms. Particularly useful lactones of this invention are those where R1 is hydrogen and RI and R2 are alkyl groups.

Furanone is a compound having the formula: (wherein R and Ro are as defined above) where R7 is a C1-2 hydrocarbon group or a C1-2 hydrocarbon group having 1 to 20 carbon atoms. and X is a leaving group, preferably a C1-H alkoxy group), such as a ketoester or a diester, is added to an aqueous base solution and reacted while maintaining the temperature at about 40° C. or lower to make the reaction mixture acidic and It is produced by a process of recovering substituted furanones. In a particularly convenient embodiment of the invention R2 is a C0-4 alkyl group.

Epoxides useful in this process include ethylene oxide and higher epoxides having single terminal or internal epoxy groups.

Particularly useful substituted lactones are epoxides with 1,2
-Epoxy alkanes, i.e. R1=R and R-C1-8
Alkyl, =10- preferably C1-. Produced when it is alkyl. Suitable 1,2-epoxyalkanes that can be used in this process include ethylene oxide, 1,2-butylene oxide,
1,2-propylene oxide, ■, 2-pentylene oxide, 1,2-epoxy-5-hexene and 1,
There is 2-hexyne/oxide.

Suitable beta-diketo compounds that can be used in this process include ethyl acetoacetate, exo-propylacetoacetate, in-propylacetoacetate, ca-butylacetoacetate, t-butylacetoacetate), 5ec-butylacetoacetate, n-butylacetoacetate, There are ketoesters, diketones and diesters such as hexylacetoacetate, 2-ethylhexylacetoacetate, exo-octylacetoacetate, in-octylacetoacetate, indecylacetoacetate, and the like.

The reaction is carried out in the presence of water and a suitable base such as a Group IA metal, preferably sodium, potassium or lithium. In the improved process of the present invention, which improves the yield of the desired furanone product, improves the reaction rate, and minimizes the formation of by-products, the epoxide and the beta-diketo compound are first mixed and then a base is added. Base addition can be carried out in sufficient contact with the reactants.

Generally, a suitable stirrer is used or the reaction mixture is circulated with a suitable pump. The base addition rate is adjusted so that the reaction mixture temperature does not exceed 40°C.

The epoxide to beta diketo compound molar ratio is about 1.1 to 1:3, preferably l:1.1 to 1:1.7.
is within the range of

Molar excesses of base up to about 5% based on the beta-diketo compound can be used, although 2 to 4% molar excesses are most commonly used.

It is best to use an aqueous solution of the base for addition. This solution can be conveniently added to a mixture of epoxide and beta-diketo compound. Aqueous solutions of sodium hydroxide and potassium hydroxide are particularly useful for this purpose. Although not essential, there may be water in the epoxide and beta diketo compound prior to addition of the base.

This is often convenient for mixing and temperature control.

Generally, sufficient water is required for the reaction, either by direct addition to the epoxide and beta-diketo compound or by addition of an aqueous base, so that a homogeneous reaction mixture can be obtained and the salts formed during the reaction can be dissolved. For this purpose, the amount of water in the reaction mixture is usually about 20 to 60% by weight. Generally 25 to 40% water, based on the total reaction mixture, is used.

After adding the base to the epoxide and beta diketo compound, the mixture temperature is maintained at about 0 to 40°C until the reaction is essentially complete. This can be conveniently done by measuring the amount of reactants remaining in the reaction mixture by gas chromatography or otherwise. The reaction time varies depending on the reactants used and reaction conditions, but is generally 1.
Within 6 hours, usually around 10 hours or less.

In this method, after the addition of the base, the temperature is kept at about 20°C until the reaction is completed.
It is particularly convenient to maintain the temperature between 35°C and 35°C.

When the reaction is substantially complete, a suitable acid is added to the mixture to neutralize it to a pH of 7 or less. Sulfuric acid is preferred for the middle phase, but organic acids can also be used. The amount of acid required will of course vary depending on the particular acid and amount of base used in the reaction. Convenient sulfuric acids that can be used for neutralization include nitric, sulfuric, hydrochloric, and hydrobromic acids. Hydrochloric acid is particularly useful for neutralization. Suitable organic acids include formic acid, acetic acid, and the like. Generally, the pH after neutralization is about 4 to 7.

After neutralization, the mixture is allowed to stand until it separates into an aqueous phase and an organic phase.

The organic phase containing the lactone product is separated from the aqueous phase containing the water-soluble acid produced during the reaction. The furanone derivative (lactone) is then recovered from the organic phase in the usual manner. When the product is to be reacted further, such as when it is used as an intermediate for the production of dihydrofuran perfumery, a simple 6" strip of alcohol at high temperature and vacuum is sufficient. In other cases, the product is fractionated. The desired 7-lanone derivative can be obtained with high purity by distillation.

The leaving group, It is a beta-keto ester which is alkoxy having 1 to 10. Using this ketoester, as the reaction progresses, the corresponding C'4-1
0 aliphatic alcohols are produced. The furanone derivatives produced are easily dissolved in this alcohol, and upon further acidification, the alcohol promotes separation of the organic and aqueous phases. The C4-8゜alkoxy group may be linear or branched, and the oxy moiety may be the first or second chain.
Alternatively, it may be located at a tertiary carbon. It is particularly convenient to use beta-ketoesters in which the alkoxy group has 5 to 8 carbon atoms, in particular the alkoxy group is branched alkoxy. This gives a very fast phase separation and high product yield, and also produces the corresponding alcohol with a boiling point that is easily separated from the furanone. R1 of the beta-ketoester is a C1-4 group, the ketoester has 3 to 6 carbon atoms, that is, R1, pH, and R is C1
When reacted with 1,2-epoxy alkanes that are -4 alkyl, the present invention provides particularly useful furanone products.

A particularly advantageous embodiment of the present invention is to
Omotsu 1,2-epoxyalkane, formula: (wherein R2 is C
8-4 alkyl group (X is a C4-10 alkyl group) and water are mixed, and the mixture is hydroxylated with stirring). 1,2-epoxyalkane to beta diketo ester, the reaction mixture containing 20 to 60% water and a 2 to 4% molar excess of base based on the beta diketo ester. Molar ratio 1:1.1 to 1
: 1.7, keeping the mixture temperature between 20 and 35°C to essentially complete the reaction, adding sulfuric acid to bring the mixture p to 4 to 7°C, separating the organic phase from the aqueous phase, and then formulating: wherein R is a 61-4 alkyl group and R3 is as defined above. In the above embodiment, it is further preferable that the 1,2-epoxyalkane is 1,2-butylene oxide or 1,2-pebutylene oxide.

Various useful furanone derivatives can be produced by the improved method of the present invention. Furanones are useful fragrances and chemical intermediates. A particularly useful 7lanone derivative that can be prepared in this manner is 3-acenal-5-butyldihydro-2(3H)-furano/. This compound has a very pleasant aroma and is useful in various perfume formulations.

The invention will be described in further detail by the following examples. Unless otherwise specified, all divisions are based on one piece.

Example ■ 3-acetyl-5-ethyldihydro-2C3H)-75
In a 500 flask with stirrer, addition funnel, condenser, water bath and thermometer, add 421 parts of sodium hydroxide and 2 parts of water.
Add 00- and cool to 15°C (ethyl acetoacetate).
13 (1 (1,0 mol)) was slowly added over 2 hours below 20°C. The mixture was stirred for a further 30 minutes at 15°C and 1
, 2-butylene oxide 107F (1.5 mol) at 1
．． Added over 5 hours. The reaction was analyzed using a gas chromatograph (
GC) Tested using standard method.

After leaving the mixture overnight, transfer it to a separate filter and add concentrated hydrochloric acid 12511
It was made acidic by adding Ll. 5011 minutes for the organic layer and 5011 minutes for the aqueous layer.
Extracted three times with 11 diethyl ether. The organic layer and extract were combined and dried over sodium sulfate, and the diethyl ether was removed by rotovup. The product 1821 was obtained and GC analysis showed 83.6% lactone and 7.8% ethyl acetoacetate.

Disadvantages Distilling the mixture using a hot tube and a shorted head, 1.8
To? - The first fractionated portion 28 was boiled at 95°C or less in
．． According to gas chromatography, 4f is lactone 3.4
It contained %. Boiling point 95-100 at 1.8 tore
The second fractionated fraction (93 °C) was included, and the yield was 57%.
Met.

Example... Sodium hydroxide 1501 in a 2t flask with a high efficiency stirrer, condenser, cooling bath, thermometer and addition filter.
and 75 (l) of water were added. The mixture was cooled to 15°C and 48 (1 (3.7 mol) of ethyl acetoacetate) was slowly added. When 25 V was added, the mixture became very viscous. Therefore, the remaining ethyl acetoacetate was mixed with 1,2-butylene oxide (350 tc, 4.8 mol) and added to the flask at 15° C. or less over a period of 2.5 hours.The reaction mixture was examined by GC standard method. was left overnight.

While keeping the flask below 25℃ (make sure to cool it)
Concentrated sulfuric acid 1[-(21(H')) was added over a period of 1 minute. The mixture became acidic and was transferred to a separate filter and sufficient hot water (approximately 21%) was added to dissolve the salt. The product was dissolved in diethyl ether The diethyl ether was removed by rotovup after drying over sodium sulfate. The material was purified by distillation using a Raschchiring packed column and a Perkins triangular head. 95-1 with part 16.2g and 2-Otorr
A second fractionated portion 337 with a boiling point of 00°C. (I got l.

It contained 91.5% furanone product with a yield of 54%.

Production of Example ■ In a 12 ton flask equipped with a stirrer, water bath, thermometer, addition funnel, and condenser, 5 parts of sodium hydroxide in 2 parts of water was added.
A solution of 54r (13.85 mol) was added. Ethylacetoacetate 1640f (12,62 mol) and 1,2-
Butylene oxide 100 (1 (13.88 mol)) was mixed, placed in an addition funnel, and added to the flask at a temperature of 20° C. over about 2.5 hours.

Stirrer hydrochloric acid 120 (1 (13,85
mol) was added over 45 minutes below 25°C. After standing still for 15 minutes, the aqueous layer was separated from the upper organic layer.

The aqueous layer was extracted three times with diethyl ether, dried over sodium sulfate, and the diethyl ether was removed by rotovup to yield 122v of product. Gas chromatography analysis revealed that it was 21% lactone.

The flask was brought to 60°C using suction vacuum (600) and the organic layer was stripped leaving a residue of 618v. Distillation of the residue using a packed tube and a Pakins triangular head resulted in products consisting of 164f, 13(1, and 114703 parts, respectively), mostly ethyl acetoacetate. The flask material was filtered and distillation continued at 5 torr. , a fourth portion 16.11 was obtained which boiled below 105°C and contained 8% lactone.A fifth portion 887g with a boiling point of 110-120°C at 5 torr was obtained which was determined by GC analysis to be the desired product. The lactone yield of the fifth portion was 42%.

Example 2 A solution of 100 parts of sodium hydroxide in 400 parts of water was placed in a 1 ton flask equipped with a stirrer, water bath, thermometer, addition funnel, and condenser. 325 g' (2.5 mol) of ethyl acetoacetate was added to the addition funnel, and the flask was cooled to 5°C. 1 ethylene oxide in the addition funnel
2 (1 (2.7 mol)) was condensed and the mixture was placed in a flask at below 15°C for 4 hours. The mixture became a thick white slurry. After 1 hour GC analysis showed ethyl acetoacetate versus product. It showed a ratio of 86:14.2,5
After time the ratio was 80:20. The mixture was placed in the freezer overnight.

The mixture was warmed to approximately 20°C and stirred for 15 minutes. GC analysis of the sample showed 3.6% ethylene glycol, 38.3% ethyl acetoacetate, and 39.8% product.
showed that.

The material was continued to be stirred for 1 hour and the temperature of the mixture rose to 24 DEG C. and analysis yielded 23.6% ethylene glycol, 70.7% ethyl acetate, and 23.6% product. The mixture was cooled to 20°C and 3 (liters) of ethylene oxide was added. Stirred for 1 hour, the water temperature rose to 24°C and GC analysis revealed 15.4% ethylene glycol, 20.7% ethyl acetoacetate, and 20.7% ethyl acetoacetate. The product was 50.9%. The mixture was stirred for 1 hour at a temperature below 20°C and neutralized with concentrated sulfuric acid 70-. Water was added to dissolve the salt and the product was extracted with diethyl ether. The extracts were combined and dried over sodium sulfate. The filtered reethyl ether was then removed using a rotovup at 50°C and a vacuum aspirator to yield the crude product 2.
47v went down.

The mixture was distilled using a Lasschich ring filled tube and a Perkins triangular head, and 7 aliquots were heated and analyzed by GC. Parts 1-3 were found to be primarily ethyl acetoacetate. Fourth
Part is ethyl acetoacetate 11% and desired lactone 4
It was analyzed to be 2%. The 5th and 6th parts are each lactone 9
8.4% and the yield (5th and 6th portions) was 32%.

Example V 3-acetyl-5-methyldihydro-2(3H)-furanone 40 (l) of water is placed in a single-layer, four-necked flask with a water bath, stirrer, dry ice condenser, thermometer, and addition funnel.
A solution of 100v of sodium hydroxide was placed inside. Mix ethyl acetoacetate 324M' (2.5 mol) and propylene oxide 1749 (3.0 mol) and add.
I put it in. The contents of the flask were cooled to 15°C and the ethyl acetoacetate and propylene oxide mixture was added over 2 hours at below 20°C. The reaction was followed by GC standard analysis.

Heat the mixture for 6 hours and transfer to a separate filter with concentrated hydrochloric acid 22
5m17! It was made acidic. The two layers were separated and the aqueous layer was extracted three times with diethyl ether. The extract was combined with the organic layer and dried over sodium sulfate, and the diethyl ether was removed by rotovup at 70° C. under suction pressure.

26-1 The resulting material was distilled using a filled tube and a Perkins triangular head.

The 1st-3rd fractionated portion 94F was mostly ethyl acetoacetate. Boiling point 112-117°C at 7 torr
The fourth portion 1701 of is essentially 100% by GC analysis.
It turned out to be a lactone. 6toτ obtained by short-circuit distillation of the residue
Substance 221 with a boiling point of 110° C. was found to contain 53% lactone 89 by GC analysis.

Production of Example ■ 2 with stirrer, thermometer, addition filter and condenser
? Ethyl acetoacetate 192r in a four neck flask
(1-47 mol), 1,2-butylene oxide 120
v (1,66 mol) and water 420? of water to a stirred solution of
An aqueous solution of 65 t (1,625 mol) of sodium hydroxide was added to No. 51 over 71 hours, and the mixture was reacted at about 25° C. for 3 hours. Transfer the mixture to a separate filter and add 20° Baume hydrochloric acid 15
51 to make it acidic. The organic portion was placed on a 40 liter vacuum and stripped at 15 torr and 60°C to yield a distillate of 29.5 r and a residue of 1518 r. The main fraction (151.8 r) and the methylene chloride extract of the aqueous phase (329) were distilled into three parts using a Raschich ring-filled tube and a Perkins triangular head as in Example (2).

The first portion was mostly unreacted ethyl acetoacetate.

The second portion, 7.6 t, contained 86.6% of the desired furanone product with a boiling point of 90-100° C. at 2 torr. The third portion 88.32 had a boiling point of 100-160°C at 2 torr and contained 93.4% lactone. The total lactone yield was 39.3% (90.4f).

Example ■ Preparation of 3-acetyl-5-ethyldihydro-2(3B)-furanone T-butyl acetoacetate 2 in a 1- to 4-necked flask equipped with an addition filter, a thermometer, a stirrer, and 7 condensers.
4'l' (1,5 mol), 1,2-butylene oxide 108r (1,5 mol), and a stirred solution of 2171 water, 64? Sodium hydroxide 64f (1.6 mol) in
An aqueous solution of was added over 50 minutes and reacted at about 25°C for 10 hours.

The mixture was transferred to a separate filter and 31% hydrochloric acid was added to reduce the pE to 6.
It was made acidic.

As in the previous example, 321.7 t of the organic phase was distilled and divided into 4 fractions. 1 torr, the fourth part with a boiling point of 90-12'0°C is the desired lactone 158.6 r)i
generated. Portions 1-3 contained mainly t-butyl alcohol and unreacted starting material with a small amount of lactone. The total lactone yield was 66.3% (155,1?). 1,
The conversion of 2-butylene oxide was 97.0% and the selectivity for the desired furanone product was 68.4%.

The improvement obtained by adding base to the mixture of epoxide, beta-keto ester and water improves the yield of this example in Example I.
This is quite clear when compared with the yield of 42 to 57% obtained with -n.

Production of Example ■ 1 with thermometer, stirrer, addition filter and condenser
? n-Butyl acetoacetacetate r-)30 in a 4-necked flask
82.5 F (20
5 mol) was added over 65 minutes at about 25°C.
The reaction was stirred for 0 hours.

The mixture was transferred to a separate filter and acidified to pE 5 with 31% hydrochloric acid.

The organic phase was separated from the aqueous phase by distillation as in the previous example to obtain 3 fractions. The third part, with a boiling point of 110-120°C, was identified by GC analysis as the lactone 151.
It was 9 f.

The first and second portions contained primarily butyl alcohol and unreacted starting material with a small amount of lactone. Total lactone yield is 64
．． It was 2% (150,4f'). The conversion rate of 1,2-ethylene oxide was 87.0% and the selectivity to the desired furanone was 7763%.

Preparation of Example (2) The following experiments were carried out to demonstrate the possibility of obtaining high yields by the process of the present invention using the preferred beta diketo ester in which the ester portion was obtained from a higher branched alcohol.

2-ethylhexylacetoacetate) 3 in a reactor equipped with a stirrer, addition funnel, condenser, water bath and thermometer.
38.4F (1,423 mol), 1,2-butylene oxide 85.47 (1,186 mol) and distilled water 140.
Mix 4t, cool to 20℃, and add 59.8 tons of distilled water while stirring.
Sodium hydroxide 59.8r (1,491 mol) in r
solution was added dropwise over 35 minutes. The maximum temperature during the addition was 34°C. The mixture was stirred at 25-31° C. for 13.5 hours and the reaction was monitored by GC analysis. After the reaction was completed, 123.5 ml of concentrated hydrochloric acid was added to bring the pE of the mixture to 5. Next, the organic phase and the aqueous phase were separated, and the organic phase was recovered and heated under vacuum.
- 185t of the desired lactone after removing ethylhexanol (
A yield of 72.4% was obtained. Selectivity to desired lactone with 90.6% conversion of 1,2-butylene oxide 79.9
%Met.

Example X Production of 3-acetyl-5-ethyldihydro-2(3H)-furanone 1,2-butylene oxide 8
5.4F (1,186 mol), isooctyl acetoacetate) 338.4r (1,423 mol) and distilled water 1
40.4r was put into the reactor and stirred. 20 minutes of this mixture
The temperature was raised to 30° C. and a solution of 59.8 f (1,494 mol) of sodium hydroxide in 59.8 f of distilled water was added dropwise over about 18 minutes. After stirring the mixture for 13 hours while keeping it at 25 to 32°C, 123.5 ml of concentrated hydrochloric acid was added. Separate the organic phase from the aqueous phase and remove unreacted materials and inoctyl alcohol by vacuum distillation using a packed tube to obtain 140.5 r of the desired lactone product.
(yield 76.0%). A conversion rate of butylene oxide of 77.7% and a selectivity to lactone of 97.9% were obtained.

EXAMPLE
(1,42 mol), 1,2-pentylene oxide 10
1.8 f (1,18 mol) and distilled water 157.5 r
were mixed. Keep the mixture between 22 and 26 with distilled water and 59.
59.6f (1,49 mol) of sodium hydroxide in 6r
After adding the solution for 1 hour, the temperature was 28-36°C.
The mixture was further stirred for 11.5 hours while maintaining the temperature. Concentrated hydrochloric acid was added to the mixture to adjust the pH to 5.8, the organic phase and the aqueous phase were separated, and then the organic phase was subjected to IJ bubbling under reduced pressure to remove octanol and unreacted octylacetoacetate. Distillation yielded 3-acetyl-5-propyldihydro-2.

Example XIl The selectivity to furanone was 76.6%.

Claims (1)

[Claims] 1. Formula: ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (However, R and R_1 represent hydrogen or C_1_-_8 alkyl groups) Epoxide and formula: ▲ Numerical formulas, chemical formulas, tables, etc. There is A formula that is characterized by reacting while keeping the reaction mixture temperature below 40°C under , and recovering the substituted furanone product after making the reaction mixture acidic: ▲There are mathematical formulas, chemical formulas, tables, etc.▼ A method for producing a substituted furanone represented by the formula (wherein R, R_1 and R_2 are as defined above). 2. The molar ratio of epoxide to beta-diketo compound is 1:
2. The method according to claim 1, wherein the ratio is 1 to 1:3. 3. In epoxide, R_1 is hydrogen and R is C_1_
The method according to claim 1 or 2, wherein the 1,2-epoxyalkane is a -_8 alkyl group. 4. The method according to claim 3, wherein R is a C_1_-_4 alkyl group. 5. The method according to claim 4, wherein the 5,1,2-epoxyalkane is 1,2-butylene oxide or 1,2-pentylene oxide. 6. In beta diketo compounds, the leaving group X is C_1_-_1
6. The method according to any one of claims 1 to 5, wherein the beta-ketoester is a _2 alkoxy group. 7. Claim 1 wherein R_2 is a C_1_-_4 alkyl group
The method described in any one of paragraphs 6 to 6. 8, R_2 is methyl and X is C_4_-_1_0
The method according to claim 7, which is an alkoxy group. 9. The molar ratio of epoxide to beta diketo compound is 1:
9. The method according to claim 1, wherein the ratio is 1.1 to 1:1.7. 10. The method according to any one of claims 1 to 9, wherein the base is an aqueous solution of sodium hydroxide or potassium hydroxide. 11. The process of claim 10, wherein there is a molar excess of base of up to 5% based on the beta diketo compound and the reaction mixture contains 20 to 60% by weight water. 12. The method according to any one of claims 1 to 11, wherein the pH of the reaction mixture is acidified to 4 to 7 with sulfuric acid. 13. The method according to claim 12, wherein the acid is hydrochloric acid. 14. 1,2-epoxyalkane having 3 to 6 carbon atoms, formula: ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (However, R_
2 is a C_1_-_4 alkyl group and X is C_4_-
_1_0 alkoxy group) and water are mixed, and an aqueous solution of sodium hydroxide or potassium hydroxide is added while stirring at such a rate that the reaction mixture temperature does not exceed 40°C. 2 based on 60% water and beta diketoester
4% to 4% molar excess of base and the molar ratio of 1,2-epoxyalkane to beta diketo is 1:1.1 to 1:
1.7, the mixture temperature is maintained at 20-35°C until the reaction is essentially complete, sulfuric acid is added to bring the mixture pH to 4-7, the organic phase is separated from the aqueous phase, and the formula : ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (In the formula, R is a C_1_-_4 alkyl group and R_2
2. The method of claim 1, wherein a substituted furanone product having the following formula is recovered to produce a furanone.