JPS62286953A - Production of cinnamic acid ester - Google Patents

Abstract

PURPOSE:To obtain the titled compound useful as a raw material for perfumery, agricultural chemicals, photo-sensitive resins, etc., suppressing the formation of by-product, in high yield, by reacting a styrene compound, an alcohol, carbon monoxide and oxygen in the presence of a catalyst using a dialkyl carbonate. CONSTITUTION:A styrene compound (e.g. styrene), an alcohol (e.g. methanol), carbon monoxide and oxygen are made to react with each other in the presence of a main catalyst consisting of palladium metal or its compound (e.g. palladium acetate) and a copper compound (e.g. copper chloride) in combination with a cocatalyst and an additive (e.g. manganous acetate) using a dialkyl carbonate having 1-4C alkyl groups (e.g. dimethyl carbonate). The reaction is preferably carried out at 40-160 deg.C under 1-300atm for 0.05-10hr. The raw material may be used as a reaction solvent or ether, nitrile, etc., may be used as the solvent.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a method for producing cinnamic acid esters, which are important as raw materials for perfumes, agricultural chemicals, photosensitive resins, and the like.

More particularly, the present invention relates to a method for producing the corresponding cinnamate esters by reacting styrenes, alcohol, carbon monoxide and oxygen.

[Conventional technology]

Conventionally, cinnamic acid has been produced on a small scale through a reaction using benzaldehyde and acetic acid derivatives as main raw materials. However, this method cannot be said to be industrially satisfactory as it requires the use of comparatively expensive raw materials. Therefore, as a method using cheaper raw materials, many methods have been reported in which styrenes, alcohol, carbon monoxide, and oxygen are reacted in the presence of a catalyst to produce cinnamate esters. 56-15242, JP 56-22749, JP 57-70836, JP 60-92242, JP 6
0 to 169442 and Japanese Unexamined Patent Publication No. 61-33144 have been proposed.

[Problem that the invention seeks to solve]

Most of these methods use at least palladium metal or its compounds and copper compounds as catalysts, but the yield and selectivity of the target cinnamate esters have not yet been sufficiently industrially satisfied. not present.

For example, in JP-A-61-33144, (al palladium metal or its compound, (bl copper or iron salt, (Cl
Salts of alkali gold metals or alkaline earth metals and (dl
A method using a catalyst consisting of an organic carboxylic acid is disclosed, but when styrene, methanol, carbon monoxide, and oxygen are used as raw materials, the yield of the target product, methyl cinnamate, is 48 to 48% based on the charged styrene. 76%, and the selectivity is 47-89% based on the consumed styrene.

That is, 30% or more of unreacted styrene remains and 10% or more of by-products are produced, and further improvement in yield and selectivity is desired from an industrial perspective.

As a result of a detailed study of the products of this reaction, the present inventors found that carbonic acid dialkyl esters were produced in addition to conventionally known phenylsuccinic acid diesters and the like as by-products.

Therefore, raw material alcohol is not only consumed in the target cinnamic acid alkyl ester and conventionally known by-products, but also is lost in the by-product of carbonate dialkyl ester, and the raw material consumption rate of alcohol is reduced. Understood.

Incidentally, it is known that dialkyl carbonate esters are produced when alcohol, carbon monoxide, and oxygen are reacted in the presence of a catalyst (for example, Chemical Abstracts 9).
Volume 1 174405e (1979) and Volume 93 1
32047a (1980), etc.) However, it has not been known until now that dialkyl carbonate esters are produced as a by-product in the reaction for producing cinnamate esters from styrenes, alcohol, carbon monoxide, and oxygen.

In view of the above, the present invention improves the yield and selectivity of cinnamate esters, reduces by-products, improves the raw material consumption rate, and simplifies the process. It's about measuring.

[Means for solving problems]

As a result of extensive studies to achieve the above object, the present inventors found that if the reaction is carried out in the presence of a certain amount of dialkyl carbonate in the reaction system, the by-product of new dialkyl carbonate can be suppressed, and that The present invention has been achieved based on the discovery that the production of by-products is also reduced, and the yield and selectivity of the target product, as well as the raw material consumption rate, are improved.

That is, the present invention provides a method for producing cinnamate esters by reacting styrenes, alcohol, carbon monoxide, and oxygen using palladium metal or a compound thereof and a copper compound as a main catalyst, in the presence of dialkyl carbonate. This is a method for producing cinnamate esters, which is characterized by reacting with cinnamate esters.

Styrenes used in the method of the present invention include:
Specifically, styrene, α-methylstyrene, β-methylstyrene, α-ethylstyrene, β-ethylstyrene, O-methylstyrene, m-methylstyrene, p-methylstyrene, m-ethylstyrene, p-ethyl Styrene, alkyl derivatives of styrene such as p-tert-butylstyrene, p-isopropyl-β-methylstyrene, or substituents that do not inhibit the reaction such as p-chlorostyrene, p-methoxystyrene, 3,4-dimethoxystyrene, etc. Examples include styrene derivatives having an aromatic ring.

In addition, these styrenes are unreacted during the reaction,
It is also possible to use as part of the raw material what is separated and recovered by a conventional method such as molten distillation.

The alcohol used in the method of the present invention includes:
methanol, ethanol, propatool, butanol,
These are aliphatic or alicyclic alcohols such as pentanol, octatool, cyclopentanol, and cyclohexanol, and they may have a substituent such as a halogen or an alkoxy group that does not inhibit the reaction. The amount of these alcohols used is 0.00% per mole of styrene.
It is preferably 5 to 100 mole parts, and may be used not only as a reaction raw material but also as a solvent.

Note that the method of the present invention may be performed in a solvent that does not inhibit the reaction. Such solvents include n-hexane, n
- Aliphatic or alicyclic hydrocarbons such as pentane and cyclohexane, aromatic hydrocarbons such as benzene, toluene, p-xylene, ethylbenzene, chlorobenzene, and dichlorobenzene, or their substituted compounds, diethyl ether, dipropyl ether, ethyl methyl ether,
Ethers such as tetrahydrofuran, dioxane, and ethylene glycol dimethyl ether, ketones such as acetone, ethyl methyl ketone, and acetophenone, esters such as methyl acetate, ethyl acetate, and methyl propionate, amide compounds such as dimethylformamide, acetonitrile, Examples include nitriles such as benzonitrile.

Palladium metal or its compound, which is the first component of the main catalyst in the method of the present invention, is, for example, palladium metal supported on a carrier such as activated carbon, silica gel, alumina, silica alumina, diatomaceous earth, magnesia, pumice, or molecular sieve. or palladium metal such as palladium black, zero-valent palladium complexes such as dibenzylidene acetone complexes of palladium or tetrakis(triphenylphosphine)palladium, halides of palladium such as palladium chloride, palladium such as palladium nitrate. Inorganic acid salts of palladium such as palladium acetate, palladium propionate or palladium benzoate, palladium bis(acetylacetonato)palladium, cyclooctadiene dichloropalladium complex, palladium chloride benzonitrile complex or palladium chloride ammine complex. Examples include divalent palladium compounds such as complexes.

The amount of these palladium metals or their compounds used is
The amount of palladium metal atoms is 0.1 gram atom or less per mole of styrene as a raw material, preferably 5×10
”~lXl0-2 gram atoms.

Examples of the copper compound which is the second component of the main catalyst in the method of the present invention include copper halides such as copper chloride and copper bromide, copper inorganic acid salts such as copper carbonate and copper nitrate, copper acetate, and propionic acid. Examples include organic acid salts of copper such as copper acid, copper stearate, copper cinnamate, and copper benzoate, and complex compounds of copper such as copper acetylacetonate and copper benzoylacetonate.

Among these, copper halides such as copper chloride and copper bromide, and organic acid salts of copper such as copper acetate and copper propionate are preferred copper compounds.

These copper compounds can be used alone or in combination of two or more. The amount of these copper compounds used is 0.004 to 11 per 11 of the reaction solution as copper atoms.
in the range of 0.4 gram atom, preferably 0.008
~0.3 gram atom.

Further, in the method of the present invention, various co-catalysts and additives can be used in order to further enhance the catalytic activity and reaction results. Examples of these co-catalysts and additives include (11) compounds of alkali metals and alkaline earth metals,
(2) organic acid salts of aluminum metal; (3) tertiary amines;
Groups 4A, 5A, and 7A of the periodic table (hereinafter simply referred to as the periodic table),
Examples include compounds of metals selected from the iron group 8A or group 2B, (7) halogen compounds, and (8) inorganic and organic acids. These may be used alone or in combination of two or more. Furthermore, a combination of compounds that can be produced within the reaction system may be used.

Specifically, these promoters and additives include (1
Compounds of metals such as sodium, potassium, rubidium, cerium, magnesium, calcium, strontium, and barium are used as the alkali metal and alkaline earth metal compounds in 1, and hydroxides of these metals,
Inorganic acid salts such as carbonates and hydrochlorides, aliphatic or aromatic mono- or polyhydric carboxylates such as acetates, propionates, butyrates, caproates, fucurates, or acetylacetone, propionylacetone β-diketones, β-ketoesters or
-keto acid complexes, etc.

In addition, as the organic acid salt of aluminum metal (2),
Examples include aluminum acetate, basic aluminum acetate, aluminum propionate, aluminum stearate, and aluminum benzoate.

(3) Tertiary amines include trimethylamine, triethylamine, tripropylamine, tributylamine, tri-secondary propylamine, diethylmethylamine,
Examples include aliphatic tertiary amines having 3 to 20 carbon atoms, such as dimethylpropylamine, allyldiethylamine, dimethylbutylamine, diethylpropylamine, benzyldimethylamine, dicyclohexylethylamine, and dimethylcyclohexylamine.

Examples of the nitriles (4) include aliphatic nitriles such as acetonitrile, propionitrile, succinonitrile, geltalonitrile, and adiponitrile, and aromatic nitriles such as benzonitrile, tolnitrile, and phthalonitrile.

Examples of the rare earth element compound (5) include scandium,
Compounds of yttrium and lanthanide elements such as lanthanum, cerium, neodymium, europium, and dysprosium are used; for example, oxides such as cesium oxide, lanthanum oxide, samarium oxide, hexapraseodymium 11 oxide, and mixtures of oxides of several rare earth elements. , or complex oxides, as well as halides such as neodymium chloride, samarium chloride, and cerium bromide, inorganic acid salts such as yttrium nitrate, cesium nitrate, cesium sulfate, and neodymium sulfate, or cesium acetate, lanthanum acetate, and benzoic acid. Examples include various compounds depending on the valence of the rare earth element, such as organic acid salts such as cerium.

(6) Metals as a compound of metals selected from group 4A, group 5A, group 7A, group 8A iron group and group 2B of the periodic table are titanium, zirconium, hafnium, vanadium, niobium, tantalum, manganese. , rhenium, iron, cobalt, nickel, zinc, cadmium, mercury, etc. Compounds of these metals include inorganic compounds such as oxides, hydroxides, halides, oxyhalides, nitrates, carbonates, and acetic acid. , fatty acid or aromatic organic acid salts such as propionic acid, stearic acid, cinnamic acid, succinic acid, benzoic acid, and phthalic acid, or complex compounds such as acetylacetonate complex and cyclopentagenyl complex. These may be used alone or in combination of two or more.

Examples of halogen compounds in (7) include halogen molecules such as chlorine, bromine, or iodine and their solutions, hydrogen halides such as hydrogen chloride, hydrogen bromide, and hydrogen iodide and their solutions, phosphorus trichloride, and pentachloride. Phosphorus, phosphorus halides such as phosphorus tribromide and phosphorus pentabromide, phosphoryl chloride,
Phosphorus oxyhalides such as phosphoryl bromide, sulfur oxyhalides such as thionyl chloride and thionyl bromide, tellurium halides such as tellurium tetrachloride and tellurium tetrabromide, titanium chloride, zirconium bromide, vanadium trichloride oxide , molybdenum chloride, manganese chloride, iron chloride, iron iodide, platinum chloride, copper chloride, copper bromide, zinc chloride, tin chloride, antimony chloride, and other metal halides or oxyhalides depending on the valence of the metal. Furthermore, it is easy to generate halogen ions such as phosgene, halogen-containing carbonic acid derivatives such as methyl chloroformate, tertiary alkyl halides such as tert-butyl chloride and tert-butyl bromide, or acid halides such as acetyl chloride and benzoyl bromide. Examples include organic halides.

These halogen compounds may be used alone or in combination of two or more.

Inorganic and organic acids in (8) include inorganic acids such as nitric acid,
Examples include fatty acids or aromatic organic acids such as acetic acid, propionic acid, stearic acid, succinic acid, benzoic acid, and phthalic acid.

In the method of the present invention, iron group 4A, 5A, 7A, 8A or 2B of the periodic table (6) among the above promoters is used.
More preferable results can be obtained by using compounds of metals selected from the group (7) and halogen compounds.

In particular, for the compound (6), compounds of manganese, cobalt, nickel, and zinc are preferable, and for the compound f7), chlorine, hydrogen chloride, hydrogen bromide, phosphorus pentachloride, phosphoryl chloride, vanadiram trichloride oxide, chromium trichloride, chloride Preferred are manganese, iron chloride, iron bromide, copper chloride, copper bromide, zinc chloride, tin chloride, bismuth chloride, and the like.

The amounts of these co-catalysts and additives to be used vary depending on the combination in which they are used, reaction conditions and reaction method.
Although it cannot be generally specified, for example, the amount of the compound (6) to be used is such that the ratio of the metal atoms contained to the copper atoms present in the reaction mixture is 0.01 to 50, preferably 0.05 to 50. It is 10. Further, the amount of the halogen compound used in (7) is 0.004 to 0.8 gram atoms per liter of reaction mixture as halogen atoms,
Preferably it is 0.008 to 0.6 gram atom.

A part of the catalyst or co-catalyst used in the method of the present invention may be a catalyst component recovered after the reaction or a catalyst component obtained by regenerating them by an appropriate method if necessary.

The carbonate dialkyl ester used in the method of the present invention is a carbonate dialkyl ester having an alkyl group having 1 to 4 carbon atoms, and specifically includes dimethyl carbonate, diethyl carbonate,
These are dipropyl carbonate and dibutyl carbonate, including each isomer. Although carbonic acid dialkyl esters having an alkyl group having 5 or more carbon atoms can also be used, they are generally expensive or difficult to obtain in large quantities, and are disadvantageous for industrial use. Furthermore, alkylene carbonates such as ethylene carbonate and propylene carbonate do not exhibit the desired effects of the present invention and are not included in the scope of the method of the present invention.

In the method of the present invention, particularly when an alcohol having 1 to 4 carbon atoms is used as a raw material, it is preferable to use a carbonate dialkyl ester having the same alkyl group as the alkyl residue of the alcohol. In this case, a part of the carbonate dialkyl ester is Those recovered from the reaction product liquid can also be conveniently used. The amount of these dialkyl carbonate esters used is 0.01 part by weight of alcohol used.
-2 parts by weight, preferably 0.1 - IM parts.

In the method of the present invention, dialkyl ester carbonate is present in the product liquid after the reaction, as a by-product of the reaction, added to the raw material system, or included in the recovered solvent or recovered raw material. When unreacted raw materials or solvents are recovered from this reaction product liquid, carbonic acid dialkyl ester is often mixed into the recovered material. However, if the amount of carbonate dialkyl ester contained in the recovered raw material or solvent is within the range of the above-mentioned amount used during the reaction, the carbonate dialkyl ester can be used as it is without separating or excluding it. Or it can be reused as part of the solvent. As a result, the carbonic acid dialkyl ester is recycled and used, while new by-products are substantially suppressed, so that favorable results are obtained.

Moreover, since there is no need to specifically separate dialkyl carbonate ester during recovery and purification of raw materials and solvents, the operation is simplified.

Of course, it is possible to separate and recover some dialkyl carbonate esters when necessary, for example, by extractive distillation (Japanese Patent Publication No. 56-1733
3) It is possible to produce highly pure dialkyl carbonate esters by pressurized distillation (Japanese Patent Publication No. 59-3463).

Further, when an organic carboxylic acid or a salt thereof is used as a part of the catalyst component or an additive in the method of the present invention, an organic carboxylic acid ester may be formed from the part. However, in the method of the present invention, it has been found that when an organic carboxylic acid ester is also present in the reaction system and the reaction is carried out, new generation of the organic carboxylic acid ester is reduced or suppressed.

Therefore, as in the case of carbonic acid dialkyl ester, the recovered solvent and recovered raw material do not necessarily have to be those from which the organic carboxylic acid ester has been separated and removed, but rather can be conveniently reused with the organic carboxylic acid ester still contained.

Of course, if necessary, the organic carboxylic acid ester can be separated from the reaction product liquid by a method such as rectification.

Furthermore, in the method of the present invention, water is produced by the reaction. Although the presence of a small amount of water during the reaction does not pose a problem, the presence of a large amount of water often inhibits the reaction. When unreacted alcohol and styrene are recovered from the reaction product liquid and reused, or when a large amount of water is present in the raw material system, it is desirable to separate or reduce the water as much as possible. For example, a dehydrating agent such as molecular sieves, silica gel, methyl orthoformate, or acetic anhydride may be used to reduce the amount of water present before or during the reaction.

The method of the invention uses carbon monoxide and oxygen as raw materials. These gases should be kept out of the explosive range.
It is preferable to use it after diluting it with an inert gas such as nitrogen or argon.

The partial pressure of carbon monoxide is 50 atm (absolute pressure, the same applies hereinafter) or less, preferably in the range of o, oos to 40 atm. The partial pressure of oxygen is 50 atmospheres or less, preferably 0.0
02 to 30 atmospheres. Air can also be used as the oxygen source.

Furthermore, when carbon dioxide is present in the reaction system, the activity of the catalyst is further increased, and cinnamate esters can be obtained with higher reaction results. When carbon dioxide is used, the partial pressure of carbon dioxide is 500 atmospheres or less, preferably 0.1 to
The pressure is 300 atm. The partial pressure of carbon dioxide with respect to the total pressure of the reaction is 10% (pressure ratio) to 98%, that is, the concentration of carbon dioxide in the reaction gas mixture is in the range of 10 to 98% by volume, more preferably 15% to 95% by volume. % range.

carbon monoxide, oxygen, and carbon dioxide when used;
Alternatively, the inert gas may be charged in the required amount into the reactor all at once, the necessary gas may be added continuously or intermittently, or a mixed gas may be passed continuously or intermittently. good. Among these methods, the method of adding and the method of distributing are more preferable methods.

The mixed gas used in the reaction may be newly prepared each time, but the residual gas used in the reaction or the exhaust gas from the distribution method may be used repeatedly after adjusting the concentration of each component gas as necessary. can.

The reaction method of the method of the present invention may be either a batch method or a continuous flow method.

The total pressure of the reaction in the method of the present invention depends on the partial pressure of carbon monoxide, oxygen and carbon dioxide, or inert gas used, but is usually 500 atmospheres or less, preferably 1 to
The pressure is 300 atm. The reaction temperature is room temperature to 200'C2, preferably 40 to 160C. The reaction time varies depending on the reaction conditions, but is usually 0.01 to 24 hours, preferably 0.0
It takes 5 to 10 hours.

After completion of the reaction, the cinnamate esters can be separated from the reaction product liquid by a commonly used separation method such as distillation or extraction. At this time, a part of the insoluble solid containing the catalyst component present or precipitated in the reaction solution can be separated by an operation such as filtration before or during the separation operation of the cinnamate ester, if necessary. Of course, the cinnamate esters may be separated from the distillation residue after separation.

〔Example〕

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

Example 1 11.23 mg of palladium acetate in a glass cylindrical container
(0,050 mmol), cupric acetate l hydrate 2.5
0 g (12,50 mmol), manganous acetate 4
Weigh out 3.82g (15.6 mmol) of aqueous salt, add a small amount of methanol to it, and then add 26.0g of styrene.
(250 mmol) and 24.1 g of dimethyl carbonate (
268 mmol), methanol that has absorbed hydrogen chloride gas (concentration approximately 0.5-2N) is mixed with hydrogen chloride in an amount of 6.25 mmol.
J mol was added, and methanol was further added to bring the total volume to 125 ml. This glass container costs 500
ml autoclave. The stirring blade of the autoclave is made of glass, and the temperature measuring tube is also protected by glass.

A mixed gas with a partial pressure ratio of carbon monoxide:oxygen:nitrogen of 10:5:85 was discharged into the autoclave at a total pressure of 51 atm.
The reaction was continued at 100° C. for 3 hours while stirring at a rate of 1/min (standard! 3). During this time, the outlet gas was discharged through a reflux condenser, and the accompanying methanol and the like were collected in a cold trap cooled to -70°C with dry ice-methanol.

After the reaction was completed, the reaction solution was cooled to several degrees and taken out, combined with the trap-collected bones, and analyzed by gas chromatography and liquid chromatography, and it was found that styrene was 9.5%.
It contained 229.8 mmol of methyl cinnamate, 3.0 mmol of dimethyl phenylchloride, and 291 mmol of dimethyl carbonate. The conversion rate of styrene was 96.2%, the yield of methyl cinnamate was 91.9%, and the yield of dimethyl phenylsuccinate was 1.2% based on the charged styrene.
%, selectivity (yield based on consumed styrene) was 95.5% for methyl cinnamate and 1.2% for dimethyl phenylsuccinate.

The net amount of dimethyl carbonate produced by subtracting the amount of dimethyl carbonate charged from the amount of dimethyl carbonate after the reaction is 23 mmol, which is 9.2 mol% per mole of styrene charged.
The ratio was

Comparative Example 1 The reaction was carried out in the same manner as in Example 1 except that dimethyl carbonate was not added. As a result, the conversion rate of styrene was 95.
1%, yield 87.1% methyl cinnamate, dimethyl phenylsuccinate 3.3%, selectivity 91.
6%, dimethyl phenylsuccinate 3.5%, and 45 mmol of dimethyl carbonate was produced. This is a 18.0 mol% ratio to the charged styrene. Comparing this result with Example 1, the addition of dimethyl carbonate to the reaction improved the yield and selectivity of methyl cinnamate;
It can be seen that the net production of dimethyl carbonate is reduced.

Example 2 In a glass cylindrical container, palladium chloride 28.4
, 16 mmol), fernic chloride 11.30 g (9,7
mmol), cupric acetate monohydrate 6.05g (30,
3 mmol), 2.99 g of manganous acetate tetrahydrate
(12.2 mmol) was weighed out, and a small amount of methanol was added thereto, followed by 83.3 g (800 mmol) of styrene and 80.2 g (890 mmol) of dimethyl carbonate.
was added, and methanol was further added to bring the total volume to 400 ml.

This glass container was placed in a 1 liter autoclave.

A mixed gas with a partial pressure ratio of carbon monoxide:oxygen dicarbon dioxide of 19:11:70 was passed through the autoclave at a total pressure of 10 atm at a rate of 1.61/min (standard condition) at the outlet while stirring was continued. The reaction was carried out for 3 hours at "C". During this time, the outlet gas was discharged through the reflux condenser and cold trap as in Example 1.

After the reaction was completed, the reaction solution was cooled and depressurized, and the collected reaction solution and the cold trap were analyzed, and the amount of styrene was 3.2.
It contained 740.8 mmol of methyl cinnamate, 11.2 mmol of dimethyl phenylsuccinate, and 942 mmol of dimethyl carbonate.

The conversion rate of styrene was 99.6%, the yield was 92.6% for methyl cinnamate, 1.4% for dimethyl cinnamate,
The selectivity was 92.9% for methyl cinnamate and 1.4% for dimethyl phenylsuccinate, and the net amount of dimethyl carbonate produced was 6.5 mol% relative to the charged styrene.

Comparative Example 2 The reaction was carried out in the same manner as in Example 2 except that dimethyl carbonate was not added. As a result, the conversion rate of styrene was 96
．． 4%, yield is 86.1% for methyl cinnamate, 3.2% for dimethyl phenylsuccinate, selectivity is 89.4% for methyl cinnamate, and 3.4% for dimethyl phenylsuccinate. , dimethyl carbonate was produced at a ratio of 15 mol % to the charged styrene.

Example 3 The amount of manganese acetate tetrahydrate used in Example 2 was changed to 11.
89 g (48.5, mmol), the amount of styrene used was 166.64 g (1600 mmol), and the amount of dimethyl carbonate was 100. OOg (1110 mmol) and the total amount after adding methanol to 500 m
The reaction was carried out in the same manner as in Example 2 except that 1 was changed.

As a result, the conversion rate of styrene was 95.0%, the yield was 88.5% for methyl cinnamate, 0.8% for dimethyl phenylsuccinate, and the selectivity was 93.2% for methyl cinnamate, and 93.2% for phenyl dimethyl cinnamate. Dimethyl succinate was 0.9%. 1100 mmol of dimethyl carbonate was detected during the reaction, the same amount as the amount charged was recovered, and no net production was observed.

In addition, 25% of methyl acetate was present in the cold trap and the reaction solution.
6 mmol was detected.

Comparative Example 3 The reaction was carried out in the same manner as in Example 3 except that dimethyl carbonate was not added. As a result, the styrene conversion rate was 94.
7%, yield is 88.0% for methyl cinnamate, 2.3% for dimethyl phenylsuccinate, selectivity is 92.9% for methyl cinnamate, 2.5% for dimethyl phenylsuccinate. Therefore, dimethyl carbonate was produced at a ratio of 5.4 mol % to the charged styrene. Also, 36.8 tons of methyl acetate was detected in the cold trap and the reaction solution.

Example 4 The reaction solution obtained in Example 3 was heated from room temperature to 80°C in a hot water bath under normal pressure.
191.5 g of the distilled fraction was collected by cooling. This fraction contains 102.5 g of methanol.
(3199 mmol), 1.9 g (2
5 mmol), 83.7 g (929 mmol) dimethyl carbonate, 3.1 g (170 mmol) water, 0.2 g (1.5 mmol) styrene, and trace amounts of acetophenone and methyl cinnamate. This recovered fraction is 190. Og and methanol 54.2 g, palladium chloride 28.4 ■, cupric chloride 1.30 g, cupric acetate monohydrate 6.05 g, manganese acetate tetrahydrate 2.99 g and styrene 166.4 The reaction was carried out under the same reaction conditions and reaction method as in Example 2 using g. As a result, the conversion rate of styrene was 95.5%, and the yield was 93% of methyl cinnamate.
．． The selectivity was 97.6% for methyl cinnamate and 0.9% for dimethyl phenyl succinate. Dimethyl carbonate was present in the cold trap and reaction solution. is 910 mmol, methyl acetate is 24
mmol was detected, and no substantial increase in these two components was observed.

Example 5 Using 1,600 mmol of styrene, 1,000 mmol of dimethyl carbonate, 0.64 mmol of palladium chloride, 10 mmol of cupric chloride, 30 mmol of cupric acetate monohydrate, and 50 mmol of manganese acetate, methanol was added to make the total amount. In the same manner as in Example 2, a mixed gas of carbon monoxide, oxygen and carbon dioxide was passed through the mixture at a total pressure of 10 atm, and the mixture was reacted at 90° C. for 2 hours. Analysis results after the reaction showed that the conversion rate of styrene was 93.0%, and the yield (selectivity) was 88.4% (95.1%) of methyl cinnamate, 0.9% (1.0%) of dimethyl phenylsuccinate. ), the net amount of dimethyl carbonate produced was 48 mmol, which was 3 mol % relative to the styrene charged.

Example 6 Using 800 mmol of styrene, 300 mmol of dimethyl carbonate, 0.04°C rimole of palladium chloride, 50 mmol of cupric acetate/l hydrate, 60.4 mmol of zinc acetate, 8.4 mmol of vanadium oxytrichloride, and methanol. was added to make the total volume 400 ml, and in the same manner as in Example 2, a mixed gas of carbon monoxide, oxygen, and carbon dioxide was passed through the mixture at a total pressure of 10 atm, and the reaction was carried out at 100° C. for 3 hours. Analysis results after the reaction showed that the conversion rate of styrene was 9268%, the yield (selectivity) was 86.0% (92.6%) of methyl cinnamate, 1.4% (1.5% of dimethyl phenyl chloride) ), the net amount of dimethyl carbonate produced was 40 mmol, which was 5 mol % relative to the styrene charged.

C Effects of the Invention] According to the method of the present invention, compared to the case where dialkyl carbonate is not used, the amount of by-product of dialkyl carbonate is substantially reduced or almost suppressed, and the amount of by-product of dialkyl carbonate is reduced, and the amount of by-product of dialkyl carbonate is reduced. By-products are also reduced, and as a result, the yield and selectivity of the target product, cinnamate esters, are improved, and the basic units of raw material styrene and alcohol are also improved, making it an economically advantageous production method.

Furthermore, according to the present invention, the carbonate dialkyl ester present in the reaction product liquid can be recovered and reused as a mixture with unreacted raw materials and solvent without any special separation operation. This is an industrially advantageous process because the separation and recovery process is simplified.

Claims (1)

[Scope of Claims] 1) A method for producing cinnamate esters by reacting styrenes, alcohol, carbon monoxide and oxygen using palladium metal or a compound thereof and a copper compound as a main catalyst, which comprises dialkyl carbonate esters. 1. A method for producing cinnamic acid esters, which comprises reacting in the presence of. 2) The method for producing cinnamate esters according to claim 1, wherein part or all of the alcohol is an alcohol containing dialkyl carbonate recovered from the reaction product liquid. 3) The method for producing cinnamate esters according to claim 1 or 2, wherein the carbon monoxide and oxygen are carbon monoxide and oxygen containing carbon dioxide.