JPH0452254B2 - - Google Patents

Description

[Detailed description of the invention]

[Field of Application of the Invention] The present invention relates to a method for producing a cinnamic acid ester, and particularly to a method for producing a cinnamic acid ester by oxidatively carbonylating styrenes in the presence of an alcohol. [Prior art] Cinnamic acid is not only used as a raw material for fragrances, such as cinnamaldehyde, cyclamenaldehyde, and β-amylcinnamaldehyde, but also as a raw material for agricultural chemicals.
It can be produced by reaction. Examples of obtaining cinnamic acid esters by oxidative carbonylation of styrene include JP-A No. 53-40709;
JP-A-56-15242, JP-A-56-22749, JP-A-56-
22750, JP-A-56-71039, JP-A-57-21342, JP-A-57-21343, and JP-A-57-70836. Among these conventional examples, those disclosing typical catalyst systems include JP-A-56-15242 and JP-A-57-70836. In JP-A-56-15242, it consists of (1) a platinum group metal or its compound, (2) a copper salt or iron salt, and (3) an organic acid salt of a metal selected from alkali metals, alkaline earth metals, and aluminum group metals. A catalyst is disclosed. Also, JP-A-57-
70836, in an ethylene glycol ether solvent, (1) platinum group metals or their salts, (2) copper or iron salts, and (3) alkali metal or alkaline earth metal hydroxides, carbonates, and acetates. Although it has been disclosed that the reaction is carried out in the presence of a catalyst consisting of one or more compounds selected from the following, the selectivity and yield of the reaction were not sufficient. Furthermore, in JP-A No. 53-40709, which was filed at the earliest of the above-mentioned conventional examples, styrene was oxidatively carbonylated in the presence of methanol using a platinum metal or its compound, a copper salt, and a tertiary amine as a catalyst. It has been reported that a trace amount of methyl cinnamate was obtained. However, in this reaction, the selectivity for methyl cinnamate is extremely low. [Object of the invention] The present invention was made to industrially advantageously produce cinnamic acid ester using inexpensive raw materials.The purpose of the present invention is to produce cinnamic acid ester with high selectivity and yield. An object of the present invention is to provide a method for producing cinnamic acid ester. [Structure of the Invention] In order to achieve this object, the present inventors have conducted extensive research on a method for producing cinnamic acid esters by oxidative carbonylation of styrenes, and have found that (a) palladium metal or its compound; , (b) salts of copper or iron, and (c) the presence of a catalyst consisting of a rare earth compound.The present invention was based on the discovery of the novel fact that cinnamic acid esters can be produced with extremely high selectivity and yield by carrying out the reaction. has been reached. That is, the present invention provides styrenes having 1 to 1 carbon atoms in the presence of a catalyst consisting of (a) palladium metal or its compound, (b) copper or iron salts, and (c) rare earth compound.
The gist of this invention is a method for producing a cinnamic acid ester, which is characterized by reacting it with an aliphatic alcohol, carbon monoxide, and oxygen. The present invention will be explained in detail below. In the method of the present invention, styrenes are reacted with an aliphatic alcohol having 1 to 4 carbon atoms, carbon monoxide, and oxygen in the presence of a specific catalyst. General formula for styrenes (In the formula, R ¹ is hydrogen, halogen, carbon number 1
~4 alkyl group or an alkoxy group having 1 to 4 carbon atoms, and R ² is hydrogen or an alkyl group having 1 to 4 carbon atoms.
6 represents an alkyl group. ), specifically, styrene,
β-methylstyrene, p-methylstyrene, p-
Examples include methoxystyrene, p-chlorostyrene, β-methyl-p-isopropylstyrene, and β-amylstyrene. Examples of aliphatic alcohols having 1 to 4 carbon atoms include methanol, ethanol, isopropyl alcohol, n-butyl alcohol, and t-butyl alcohol.
Examples include -butyl alcohol, but compounds that can be dissociated in the reaction system to release the above-mentioned alcohol, such as acetals, ketals, orthoesters of carboxylic acids, dialkoxycycloalkanes, and orthoboric acid esters, can also be used. In the production method of the present invention, in order to obtain a higher production yield of cinnamic acid ester, it is preferable to maintain the dissolved molar ratio of styrenes to the aliphatic alcohol in the reaction system at 0.5 to 1.5. Carbon monoxide and oxygen can be used in a pure state, but they can also be used diluted with an inert gas such as nitrogen or argon. In order to obtain a higher yield of cinnamic acid ester, it is necessary to maintain the carbon monoxide partial pressure in the reaction system between 0.1 Kg/cm ² G and 10 Kg/cm ² G and reduce the monoxide relative to the oxygen partial pressure in the reaction system. It is preferable to maintain the carbon partial pressure ratio between 1.0 and 2.5. In the method of the present invention, the reaction is carried out in the presence of a catalyst consisting of (a) palladium metal or a compound thereof, (b) a salt of copper or iron, and (c) a rare earth compound. Examples of palladium metal or its compounds include palladium black, metal palladium such as supported metal palladium, or zero-valent palladium complexes such as tetrakis(triphenylphosphine)palladium; inorganic salts of divalent palladium such as palladium chloride and palladium nitrate. ; Divalent palladium carboxylates such as palladium acetate and palladium benzoate; Bis(acetylacetonato)palladium, bis(triphenylphosphine)dichloropalladium, etc.
Examples include palladium compounds such as valent palladium complexes. When using these palladium metals or their compounds supported on a carrier, silica, alumina, silica alumina, magnesia, titania,
Diatomaceous earth, activated carbon, graphite, barium carbonate,
Calcium carbonate and the like are used as carriers. Examples of copper or iron salts include inorganic salts such as hydrochlorides, nitrates, sulfates, phosphates, borates, and organic acid salts such as acetates and benzoates. The valence of copper in salts may be monovalent or divalent,
Further, the valence of iron may be divalent or trivalent. Examples of rare earth compounds include oxides, composite oxides, or salts of a total of 17 elements, including scandium and yttrium of Group 3a, and lanthanoids from lanthanum to lutetium. Specifically, oxides include basic oxides such as CeO ₂ , Pr ₆ O ₁₁ , La ₂ O ₃ , etc. Complex oxides include mixtures of several types of rare earth elements (generally called Mitsushi metal). ) complex oxides. Examples of salts include inorganic acid salts such as hydrochloride and nitrate, and organic acid salts such as acetate. (a), (b) in the catalyst used in the method of the present invention,
(c) The mixing ratio of the three components is such that the atomic ratio of (a) palladium metal or its compound and (b) copper or iron salt is in the range of 1:0.1 to 500, preferably 1:10 to 300. It is preferable to adjust the ratio of (b) copper or iron salts and (c) rare earth compound so that the atomic ratio is in the range of 1:0.01 to 100, preferably 1:0.1 to 50. It is. In the present invention, there is no problem even if no reaction solvent is used, but in some cases, an appropriate inert solvent may be used to facilitate the operation. Examples of solvents include diethyl ether, diphenyl ether, dioxane, tetrahydrofuran,
Ethers such as ethylene glycol dimethyl ether; Ketones such as acetone, methyl ethyl ketone, dibutyl ketone, acetophenone; Esters such as methyl acetate, ethyl acetate, ethyl propionate, benzyl benzoate, dimethyl phenylsuccinate; benzene, toluene, p-xylene , aromatic hydrocarbons such as ethylbenzene; aliphatic or alicyclic hydrocarbons such as n-hexane, n-octane, and cyclohexane; amides such as acetamide and N-methylpyrrolidone; ethylene carbonate, propylene carbonate, etc. Examples include carbonates. In the production method of the present invention, the yield of cinnamic acid ester can be improved by increasing the reaction temperature, but if it is too high, side reactions such as the production of carbon dioxide may occur, resulting in a decrease in the selectivity of cinnamic acid ester. decreases. Therefore, it is appropriate that the reaction temperature is usually within the range of room temperature to 200°C, preferably 50 to 150°C. The desired cinnamic acid ester can be easily separated and obtained from the reaction product liquid obtained by the reaction of the present invention by employing ordinary separation means such as distillation and extraction. By the method of the present invention, the general formula (In the formula, R ¹ and R ² are the same as defined above) Through the oxidative carbonylation reaction of styrenes, the general formula (wherein R ¹ and R ² are the same as defined above,
R ³ represents an alkyl group having 1 to 4 carbon atoms. ) is obtained. [Examples of the Invention] The present invention will be explained in more detail by Examples below, but the present invention is not limited to the following Examples unless the gist of the invention is exceeded. Example 1 Styrene 7 ml, methanol 3 ml,
5% Pd/AC (5% by weight palladium supported on activated carbon) 0.25 mmo (Pd equivalent), cupric chloride 0.5 mmo, lanthanum oxide (La ₂ O ₃ ) 1.5 mmo
After the container was sealed, 8 kg/cm ² G of carbon monoxide was press-injected. Next, 6% O ₂ /N ₂ (nitrogen containing 6% by volume of oxygen) was injected to make the total pressure 102 Kg/cm ² G. Thereafter, the autoclave was heated to 100°C and reaction was carried out for 1 hour. After the reaction was completed, the autoclave was water-cooled and depressurized, and the compositions of the reaction gas and product liquid obtained were analyzed by gas chromatography to determine the amount and selectivity of methyl cinnamate produced and the amount of carbon dioxide produced. The results are shown in Table 1. Note that the selectivity of methyl cinnamate was calculated using the following formula. Methyl cinnamate selectivity = (methyl cinnamate) ÷ (methyl cinnamate + methyl 2 and 3 propionate + acetophenone + dimethyl phenylsuccinate) x 100 Examples 2 to 10 The rare earth compounds and their addition amounts in Example 1 are shown in Table 1. The reaction and analysis were carried out in the same manner as in Example 1 except as shown, and the amount and selectivity of methyl cinnamate produced and the amount of carbon dioxide produced were determined. The results are shown in Table 1. Example 11 In Example 1, 0.05 mmo of 5% Pd/AC
(in terms of Pd), the reaction and analysis were carried out in the same manner as in Example 1, except that the cupric chloride was changed to 10 mmo, and the charging pressure of carbon monoxide was changed to 15 kg/cm ² G. The production amount, selectivity, and carbon dioxide production amount were determined. The results are shown in Table 1.

〔Effect of the invention〕

According to the method for producing cinnamic acid esters of the present invention detailed above, styrenes are oxidized in the presence of a catalyst consisting of (a) palladium metal or its compound, (b) salts of copper or iron, and (c) rare earth compounds. Cinnamic acid esters can be produced with high selectivity and yield by selective carbonylation. Furthermore, the method of the present invention allows the production of cinnamic acid esters using inexpensive raw materials and catalyst systems, which is extremely advantageous industrially.

Claims (1)

[Scope of Claims] 1. Styrenes are mixed with a fatty acid having 1 to 4 carbon atoms in the presence of a catalyst consisting of (a) palladium metal or its compound, (b) copper or iron salts, and (c) a rare earth compound. A method for producing a cinnamic acid ester, characterized by reacting it with a group alcohol, carbon monoxide and oxygen. 2. In the method for producing a cinnamic acid ester according to claim 1, styrenes have the general formula (In the formula, R ¹ is hydrogen, halogen, carbon number 1
~4 alkyl group or an alkoxy group having 1 to 4 carbon atoms, and R ² is hydrogen or an alkyl group having 1 to 4 carbon atoms.
6 represents an alkyl group. ) A manufacturing method characterized by using styrenes represented by 3. The method for producing a cinnamic acid ester according to claim 2, characterized in that the styrene is styrene. 4. In the method for producing a cinnamic acid ester according to any one of claims 1 to 3,
A manufacturing method characterized in that the rare earth compound is a rare earth oxide. 5. In the method for producing a cinnamic acid ester according to any one of claims 1 to 3,
A manufacturing method characterized in that the rare earth compound is an organic acid salt of a rare earth element. 6. In the method for producing a cinnamic acid ester according to any one of claims 1 to 5,
A manufacturing method characterized in that the ratio of (a) palladium metal or its compound to (b) copper or iron salts is in an atomic ratio of 1:0.1 to 500. 7. In the method for producing a cinnamic acid ester according to any one of claims 1 to 6,
A manufacturing method characterized in that the ratio of (b) copper or iron salts to (c) rare earth compound is in an atomic ratio of 1:0.01 to 100.