JPH04288071A - Production of esters - Google Patents

Abstract

PURPOSE:To produce cyclic esters from a cyclic ketone compound and hydrogen peroxide using arsonic acids as a catalyst in high yield at a high rate of reaction. CONSTITUTION:A cyclic ketone compound is reacted with hydrogen peroxide using arsonic acids expressed by the formula (R is 1-12C alkyl group or aryl group and hydrogens in the aryl group may be substituted with hydroxyl group, carboxyl group, sulfone group, amino group, alkyl group, alkyloxy group or halogen atom) while keeping a reaction medium in a substantially anhydrous state to produce the objective cyclic esters in high yield at a high rate of reaction.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to an improved method for producing cyclic esters from a cyclic ketone compound and hydrogen peroxide, and more specifically, the present invention relates to an improved method for producing cyclic esters from a cyclic ketone compound and hydrogen peroxide. The present invention relates to a method for producing cyclic esters from.

0002

2. Description of the Related Art Japanese Patent Publication No. 44-10243 discloses a method of oxidizing ketones with hydrogen peroxide in the presence of an organic or inorganic arsenic compound as a catalyst. Preferred arsenic catalysts include arsenate, arsenite, arsenic oxide, and the like. Furthermore, JP-A-55-21481 discloses that hydrogen peroxide can be used as a catalyst to form polyphenylene or to form a ketone using hydrogen peroxide using a granular or bead-like porous polymer in which arsenic groups are pendant from a polymethylene skeleton cross-linked with divinylarylene. Several oxidation methods have been disclosed. Japanese Patent Publication No. 1-35814 discloses at least one type of HF,
In a method for producing a carboxyl compound by reacting a cyclic ketone or aldehyde with hydrogen peroxide in the presence of a Friedel-Crafts catalyst such as SbF5 or SnCl4, water is continuously removed from the liquid reaction mixture by evaporation to substantially reduce the reaction mixture. A method for producing a carboxyl compound which is maintained in an anhydrous state is disclosed.

0003

[Problems to be Solved by the Invention] However, according to the studies of the present inventors, the method disclosed in Japanese Patent Publication No. 10243/1988 produces a large amount of by-products and has a low yield unless a solvent is used. . Furthermore, the method disclosed in JP-A-55-21481 produces many by-products unless high concentration hydrogen peroxide is used. Furthermore, since a resin is used as a carrier, the reaction cannot be carried out at relatively high temperatures. Also, the yield and reaction rate are low. Although the method disclosed in Japanese Patent Publication No. 1-35814 has a high reaction rate, the yield is low unless high concentration hydrogen peroxide is used. Also, although the system is virtually anhydrous,
Since it uses corrosive hydrogen fluoride and a catalyst that generates hydrogen fluoride and hydrogen chloride through hydrolysis, it requires the use of an expensive corrosion-resistant reaction vessel, which has major drawbacks from an industrial perspective.

0004

[Means for Solving the Problems] As a result of studies to solve the above-mentioned problems, the present inventors used arsonic acids represented by the following general formula (1) among arsenic compounds as a catalyst, and By removing water and keeping the reaction medium in a homogeneous phase and substantially anhydrous state, cyclic esters can be produced by hydrogen peroxide oxidation of cyclic ketone compounds in high yields and at high reaction rates. They discovered this and completed the present invention. (Here, R is an alkyl group or an aryl group having 1 to 12 carbon atoms, and the hydrogen of the aryl group is substituted with a hydroxyl group, a carboxyl group, a sulfone group, an amino group, an alkyl group, an alkyloxy group, or a halogen atom. Also good.)

[
The arsonic acids used in the present invention have strong oxidation resistance, and can be separated by distillation after the reaction and recycled to the reaction system, or extracted and separated with water or other solvent, recycled to the reaction system, and recycled. It is a very stable compound that can also be used. Next, the catalyst of the present invention and the method for producing cyclic esters from a cyclic ketone compound and hydrogen peroxide using this catalyst will be specifically explained. The arsonic acid serving as a catalyst in the present invention is represented by the following general formula (1). (Here, R is an alkyl group or an aryl group having 1 to 12 carbon atoms, and the hydrogen of the aryl group is substituted with a hydroxyl group, a carboxyl group, a sulfone group, an amino group, an alkyl group, an alkyloxy group, or a halogen atom. Also good.)

[
Next, specific examples of substituents are listed below. Examples of alkyl groups include methyl, ethyl, butyl, pentyl,
Hexyl, heptyl, octyl, nonyl, decanyl, undecanyl, dodecanyl, cyclohexyl, etc.
In addition to unsubstituted phenyl and naphthyl groups, the aryl group includes unsubstituted phenyl and naphthyl groups in which one or more hydrogen atoms are substituted with the following substituents. Substituents include hydroxy, sulfone, carboxy, amino, methylamino, dimethylamino, ethylamino, diethylamino, and salts of these groups such as sulfonium, carbonium, and ammonium bases. Furthermore, alkyl groups having 1 to 6 carbon atoms, alkoxy groups having 1 to 6 carbon atoms, phenoxy, chloro, fluoro,
Brome is used as a substituent. Among these, preferred arsonic acids include phenylarsonic acid, butylarsonic acid, and p-methoxyphenylarsonic acid. The catalyst used may be immobilized on an organic or inorganic carrier as required. These arsonic acids can be selected depending on the desired cyclic ester, depending on process requirements such as separation from the reaction solution and recycling, as well as reaction yield.

The reaction between the cyclic ketone compound and hydrogen peroxide in the present invention is carried out as follows. The amount of catalyst used is 100 g or less per 1 kg of reaction liquid, 0.1 g to 75 g,
Preferably, it is used in a proportion of 0.5 to 50 g. The catalyst can be introduced into the reaction system by various known methods. For example, it may be used as a pure crystal or dissolved in one of the components in the reaction solution.

In the present invention, the above-mentioned arsonic acids alone are highly active as catalysts, but in order to increase the stability of hydrogen peroxide and maintain the activity of the arsonic acids, polymerization and decomposition of the product are also carried out. Additives can be added to prevent this. Examples of additives include hydrogen peroxide stabilizers, polymerization inhibitors, and peroxide decomposition inhibitors. Examples of additives include EDTA, EDTA sodium salt,
These include stearic acid, phthalic anhydride, phthalic acids, various phosphoric acids and phosphates, and tin compounds. These additives can be used in a wide range, but are typically used in amounts ranging from 0.01 to 1 g per gram of catalyst.
2g, preferably 0.05-0.5g is used.

Preferred cyclic ketone compounds used in the present invention are cyclopentanone, cyclohexanone, methylcyclohexanone, cyclohexenone, cyclooctanone, fluorenone, naphthoquinone, and the like.

In the present invention, hydrogen peroxide can be used either as an aqueous solution or as a solution in an organic solvent. Therefore, the selection can be determined by process requirements. Usually an aqueous solution is used. The concentration of the hydrogen peroxide solution used can be selected within a wide range. In general, aqueous solutions of 10% by weight or more are used, but those exceeding 90% by weight are not recommended from the viewpoint of operability, safety, etc. The preferred range is 20~
It is 80% by weight.

In the present invention, the ratio of the cyclic ketone compound and hydrogen peroxide in the reaction medium can be selected within a wide range depending on the reaction rate, the solvent used, etc., but usually the number of moles of hydrogen peroxide is the same as the number of moles of the cyclic ketone compound. not exceed 1.5 times.

In the present invention, a solvent can be used in addition to the cyclic ketone compound, hydrogen peroxide, and the catalyst. Generally, the solvent used is one that is inert under the reaction conditions. Suitable solvents include ethers, alcohols, halogenated hydrocarbons, hydrocarbons, carboxylic esters, phosphoric esters, and the like. Ethers include ethers having 4 to 14 carbon atoms;
Examples include diethyl ether, diphenyl ether, diglyme, and tetrahydrofuran. Examples of the alcohol include monovalent or polyvalent primary, secondary or tertiary alcohols having 1 to 12 carbon atoms, such as methanol, ethanol, tert-butanol, cyclohexanol, ethylene glycol, 1,4-butanediol, etc. . The halogenated hydrocarbon is an aliphatic or aromatic halogenated hydrocarbon having 2 to 10 carbon atoms, preferably a halogenated hydrocarbon substituted with chlorine and/or fluorine. Hydrocarbons include aliphatic or aromatic hydrocarbons having 6 to 20 carbon atoms, such as n-hexane, cyclohexane,
Examples include decane, benzene, toluene, xylene, and mesitylene. Carboxylic acid ester has 2 carbon atoms
-6 aliphatic or alicyclic esters such as methyl acetate, phenyl acetate, methyl propionate, methyl caproate, ε-caprolactone, and the like. The phosphoric ester is a phosphoric ester having 3 to 21 carbon atoms, such as trimethyl phosphate, triethyl phosphate, triphenyl phosphate, and the like. In addition to the above-mentioned inert solvents, carboxylic acids such as organic acids such as acetic acid, propionic acid, and caproic acid can also be used as solvents. At this time, a part of the organic acid becomes a peracid, which may accelerate the reaction and suppress the production of by-products.

The proportion of the solvent to be used can be selected within a wide range, but it is usually used in the range of 5 to 90% by weight. Generally, when a cyclic ketone is used as a raw material, a solvent is often not used because the raw material also serves as a solvent.

[0016] In the present invention, the reaction temperature is usually 150°C or lower,
Generally in the range of 50 to 130°C, especially in the range of 90 to 125°C.
Good results are obtained at temperatures of °C. The reaction pressure varies depending on the method of removing water from the reaction system, but is 1 x 103 Pa~
It can be selected within the range of 3×105 Pa.

The water in the reaction system is preferably removed by azeotropic distillation of the reaction solvent or raw material cyclic ketone compound with water. In this case, if the azeotropic temperature is higher than the reaction temperature, either the reaction may be carried out under reduced pressure or an inert gas may be blown in to entrain steam. In addition, physicochemical or chemical methods of removing water are also possible. It can be taken as crystallization water of an inorganic salt or into the cavity of a molecular sieve, or it can be reacted with an acid anhydride to remove water from the system. In these cases, continuous reaction is possible by drying, dehydrating, and reusing the compound that has acted as a dehydrating agent. If a large amount of water exists in the reaction system, the reaction medium will separate into two phases, an organic phase and an aqueous phase, which will cause a decrease in the reaction rate and an increase in the production of peroxides. hydrolyzes the cyclic ester produced, resulting in a decrease in yield. In order to obtain a good reaction yield, good results can be obtained by keeping the concentration of water in the system below the range in which the reaction medium and water form a homogeneous phase, 2% by weight or below. The range is 0.5% by weight or less, and 0.2% by weight or less is particularly preferred. The invention can be carried out in a single reactor or in a series of multi-vessel reactors, and either continuously or discontinuously. Furthermore, it can also be carried out in a tubular reactor.

[0018]

EXAMPLES Next, the present invention will be explained in more detail with reference to Examples and Comparative Examples.

Example 1 88 g of cyclohexanone and 1 g of phenylarsonic acid were placed in a reaction flask, and the temperature was raised to 120° C. while stirring. Subsequently, 10.8 g of 60% hydrogen peroxide solution was introduced over 2 hours. During this time, nitrogen gas was blown into the system to remove water by azeotropy. After the reaction was completed, the reaction solution was analyzed by high performance liquid chromatography, and 18.4 g of ε-caprolactone was found to have been produced. The yield based on hydrogen peroxide was 85%. The water content in the reaction system was 0.08% by weight.

Comparative Example 1 An experiment was carried out in the same manner as in Example 1, except that nitrogen gas was not blown in to remove water by azeotropy. After the reaction was completed, analysis of the reaction solution revealed that 6.7 g of ε-caprolactone had been produced, and the yield based on hydrogen peroxide was 31%. Also, large amounts of by-products such as peroxide were produced. In this case, the reaction medium separated into two phases and the average water concentration was 13.9% by weight. This comparative example shows that the effect of removing water from the reaction system is large.

Example 2 Butylarsonic acid was used instead of phenylarsonic acid in Example 1, and 60% hydrogen peroxide solution was added at a reaction temperature of 120°C.
The same operation as in Example 1 was performed except that 0.8 g was introduced over 2 hours. After the reaction was completed, analysis of the reaction solution revealed that 15.4 g of ε-caprolactone was produced.
The yield based on hydrogen peroxide was 71%. Further, the water content in the reaction system was 0.2% by weight.

Example 3 p-methoxyphenylarsonic acid was used instead of phenylarsonic acid in Example 1, and the reaction temperature was 120° C. to 60%.
The same operation as in Example 1 was performed except that 10.8 g of hydrogen peroxide solution was introduced over 1.5 hours. After the reaction is complete,
Analysis of the reaction solution revealed that 18.0 g of ε-caprolactone was produced, and the yield based on hydrogen peroxide was 83%. Further, the water content in the reaction system was 0.06% by weight.

[0023]

Effects of the Invention When producing cyclic esters from a cyclic ketone compound and hydrogen peroxide, high yields can be obtained by using arsonic acids as a catalyst and maintaining the reaction medium in a substantially anhydrous state as in the present invention. Moreover, it can be produced at a high reaction rate.

Claims (1)

[Scope of Claims] [Claim 1] A method for producing cyclic esters from a cyclic ketone compound and hydrogen peroxide, in which an arsonic acid represented by the following general formula (1) is used as a catalyst, and the reaction medium is substantially Cyclic esters characterized by being kept in an anhydrous state (where R is an alkyl group or an aryl group having 1 to 12 carbon atoms, and the hydrogen of the aryl group is a hydroxyl group, carboxyl group, sulfone group, or amino group) , may be substituted with an alkyl group, an alkyloxy group, or a halogen atom.)
2. The method according to claim 1, wherein the arsonic acid is phenylarsonic acid. 3. The production method according to claim 1, wherein the arsonic acid is a phenylarsonic acid in which at least one hydrogen of the phenyl group is substituted with a hydroxyl group, a carboxyl group, a carbonium group, a sulfone group, or a halogen atom. 4. The production method according to claim 1, wherein the cyclic ketone compound is cyclohexanone and the cyclic ester is ε-caprolactone. 5. The process according to claim 4, wherein water is removed from the reaction medium during the reaction by distillation of the water-cyclohexanone azeotrope, and the concentration of water in the reaction medium is maintained below 2% by weight.