JPS6323984B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing cinnamic acid esters by oxidatively carbonylating styrenes in the presence of alcohol. Cinnamic acid is used as a fragrance raw material along with cinnamaldehyde, cyclamenaldehyde, β-amylcinnamaldehyde, etc., and on a laboratory scale
It can be produced by Perkin reaction. An example of obtaining a cinnamic acid ester by the oxidative carbonylation reaction of styrene is given in JP-A No. 53-40709.
reported that trace amounts of methyl cinnamate were obtained by oxidative carbonylation of styrene in the presence of methanol using palladium chloride, cupric chloride, and tributylamine as catalysts. However, in this reaction, methyl cinnamate is produced in an amount of several percent of the main product, dimethyl phenylsuccinate, and is only produced in an amount of 106 mol % based on palladium. The present inventors investigated various methods for producing cinnamic acid esters by oxidative carbonylation of styrenes, and found that styrenes were converted to aliphatic alcohols, carbon monoxide, and oxygen in the presence of palladium, halogen, and dehydrating agent. The present invention was achieved based on the discovery that cinnamic acid esters can be produced at a high reaction rate and in good yield by reacting with the following. The present invention will be explained in detail below. The raw materials used in the method of the present invention 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 represents hydrogen or an alkyl group having 1 to 6 carbon atoms. ), aliphatic alcohols having 1 to 4 carbon atoms,
carbon monoxide and oxygen. Specifically, styrenes include styrene, β-
Examples include methylstyrene, p-methylstyrene, p-methoxystyrene, p-chlorostyrene, β-methyl-p-isopropylstyrene, and β-amylstyrene. Specific examples of aliphatic alcohols having 1 to 4 carbon atoms include methanol, ethanol, isopropyl alcohol, n-butyl alcohol, t-butyl alcohol, etc.; Compounds that can be dissociated in the reaction system to release the above-mentioned alcohol, such as acid orthoesters, dialkoxycycloalkanes, orthoboric acid esters, can also be used. 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 general, the lower the carbon monoxide partial pressure, the higher the selectivity of cinnamic acid esters, so it is adjusted to normal pressure to 100Kg/cm ² , preferably normal pressure to 50Kg/cm ² , and the oxygen partial pressure is in the explosive range. is selected arbitrarily in areas that are not needed. The reaction according to the process of the invention is carried out in the presence of palladium, halogen and a dehydrating agent. Examples of palladium include palladium black, metallic palladium such as supported metallic palladium, zero-valent palladium complexes such as tetrakis(triphenylphosphine)palladium, inorganic salts of divalent palladium such as palladium chloride and palladium nitrate, palladium acetate, and benzoic acid. divalent palladium carboxylates such as acid palladium, α-picolinate palladium, bis(acetylacetonato)palladium, bis(triphenylphosphine)dichloropalladium, cyclooctadiene dichloropalladium, tetraammine dichloropalladium, etc. Examples include palladium complexes. When these palladiums are supported on a carrier, silica, alumina, silica alumina, magnesia, titania, diatomaceous earth, activated carbon, graphite, etc. are used as the carrier.
The amount of palladium to be used is selected in the range of 1 to 1000 milligram atoms in terms of palladium element per mole of raw material styrene. As the halogen, halogen compounds such as chlorine, bromine, and iodine are usually used. For example, halides of alkali metals such as lithium, potassium, and cesium, halides of alkaline earth metals such as magnesium, calcium, and barium, halides of group 1B metals such as copper, and halides of group 1B metals such as zinc and mercury.
Group metal halides, 3B group metal halides such as aluminum, titanium, zirconium, etc.
Halides of group 4B metals, halides of group 4B metals such as tin, halides or oxyhalides of group 5A metals such as panadium, antimony,
Halides of group 5B metals such as bismuth, halides of group 6A metals such as molybdenum and chromium, halides of group 7A metals such as manganese, halides of lanthanoids such as lanthanum, ammonium halides, tetramethylammonium halides,
Examples include ammonium halides such as tetraethylammonium halide. Particularly preferred are alkali metal or alkaline earth metal halides. Halogen has an atomic ratio of 1 to palladium.
~50, preferably 2.5 to 30. If palladium or the redox agent described below is a halogen-containing compound, it is not necessary to add it separately, but it is preferable to add it in terms of reaction rate, selectivity, etc. . As a dehydrating agent, dimethoxymethane, 1,1,
Acetals such as 2-trimethoxyethane, 2,2
- Ketals such as diethoxypropane, orthoesters of carboxylic acids such as methyl orthoformate, ethyl orthoformate, isopropyl orthoformate, and t-debutyl orthoformate, dialkoxycycloalkanes such as dimethoxycyclohexane, triethyl borate, trioctyl borate Examples include orthoboric acid esters such as In the oxidative carbonylation reaction of the present invention, one molecule of water is produced when one molecule of cinnamic acid ester is produced from one molecule of styrene, so the stoichiometric amount is sufficient to dehydrate the water produced in the reaction. It is preferable to use the above dehydrating agents. In the method of the present invention, a redox agent may be present in order to further increase the activity of the catalyst system. Such redox agents include manganese salts or complexes such as manganese acetate, manganese nitrate, manganese bromide, bis(benzoin oxime) manganese, iron acetate, iron chloride, iron iodide, iron oxalate, iron trifluoroacetate, and tetrafluoride. Iron salts or complexes such as iron enylporphyrin, cobalt acetate, cobalt chloride, cobalt bromide, cobalt salts or complexes such as cobalt (salicylaldehyde ethylene diiminate), copper acetate, copper chloride, copper sulfate, copper nitrate, copper nitrate Copper salts of iron, vanadium trichloride, vanadium pentachloride,
Examples include salts or complexes of metals whose oxidation potential is higher than that of palladium, typified by vanadium salts such as vanadium oxytrichloride. For each gram atom of palladium, these redox agents
It is preferably used in a proportion of 0.1 to 100 moles. There is no problem even if no reaction solvent is used, but
If necessary, a suitable inert solvent may be used to facilitate the operation. For example, diethyl ether, diphenyl ether, dioxane,
Ethers such as tetrahydrofuran and ethylene glycol dimethyl ether, ketones such as acetone, methyl ethyl ketone, dibutyl ketone, and acetophenone, methyl acetate, ethyl acetate, acetic acid n-
Carbonization of esters such as butyl and methyl propionate, aromatic hydrocarbons such as benzene, toluene, p-xylene, and ethylbenzene, and aliphatic or alicyclic compounds such as n-pentane, n-hexane, n-octane, and cyclohexane. Examples include hydrogens, carbonates such as ethylene carbonate and propylene carbonate, and nitro compounds such as nitromethane and nitrobenzene. Moreover, the aliphatic alcohol used as a reaction raw material can also be used in excess so as to serve as a solvent. In the method of the present invention, the selectivity of cinnamic acid ester can be improved by increasing the reaction temperature, but if it is too high, the selectivity of cinnamic acid ester will decrease due to the occurrence of side reactions such as combustion. , usually room temperature to 200℃, preferably 50℃
The reaction is carried out at a reaction temperature in the range of ~150°C. The cinnamic acid ester can be separated from the reaction product liquid obtained by carrying out the method of the present invention by employing conventional separation means such as distillation and extraction. Next, the present invention will be explained in more detail with reference to Examples. Example 1 275 mmol of methyl orthoformate and methanol were placed in a rotary stirring titanium autoclave with an internal volume of 200 ml.
12.0mmol, styrene 87.5mmol, palladium chloride
1.64 mmol, cupric chloride 3.4 mmol and lithium chloride 2.7 mmol, and after sealing, carbon monoxide 20
Kg/cm ² was press-fitted. Then autoclape 120
℃ and 95Kg/cm ² of nitrogen containing 6% oxygen by volume.
The reaction was carried out for 2.5 hours. After the reaction is complete,
The autoclave was cooled and depressurized, and the resulting liquid was analyzed by gas chromatography. The results are shown in Table-1. Examples 2 to 4 Reactions were carried out under the same reaction conditions as in Example 1, except that the reaction temperature or carbon monoxide partial pressure was changed as shown in Table 1. The results are shown in Table-1.

[Table] Example 5 The reaction was carried out in the same manner as in Example 2, except that 2.9 g of activated carbon supporting 5 wt% of metal palladium was used instead of 1.64 mmol of palladium chloride.
As a result, the styrene conversion rate was 73%, and the amounts of methyl cinnamate and dimethyl phenylsuccinate produced were 25 mmol and 25 mmol, respectively. Example 6 The reaction was carried out in the same manner as in Example 2 except that 245 mmol of 2,2-dimethoxypropane was used instead of methyl orthoformate. As a result, the conversion rate of styrene was 69%, and the production amounts of methyl cinnamate and dimethyl phenylsuccinate were respectively
They were 39 mmol and 11 mmol. Comparative Example 1 A reaction was carried out under the same reaction conditions as in Example 1 except that orthoformic acid ester was not used.
As a result, the production amounts of methyl cinnamate and dimethyl phenylsuccinate were 0.7 mmol and 0.7 mmol, respectively.
The amount produced was 0.9 mmol, and the amount produced was extremely small. Example 7 Calcium chloride instead of lithium chloride
The reaction was carried out in the same manner as in Example 2, except that 3.4 mmol was used and cupric chloride was not used. The effect was that the styrene conversion rate was 92%, and the amounts of methyl cinnamate and dimethyl phenylsuccinate produced were 42 mmol and 19 mmol, respectively. Example 8, Comparative Example 2 In order to confirm the influence of halogen on the reaction, the reaction was carried out under the same conditions as in Example 2 except that the catalyst system was changed to that shown in Table 2. The results are shown in Table-2.

[Table] Example 9 The reaction was carried out in the same manner as in Example 2 except that methanol was not used and the carbon monoxide partial pressure was changed to 18 Kg/cm ² . As a result, the styrene conversion rate was 83%, and the production amount of methyl cinnamate and dimethyl phenylsuccinate was 47 mmol each.
and 13 mmol. Example 10 β-methylstyrene instead of styrene
The reaction was carried out in the same manner as in Example 9 except that 77 mmol was used. As a result, 12 mmol of methyl α-methylcinnamate and 5 mmol of dimethyl α-phenyl-β-methylsuccinate were produced. Example 11 p-methoxystyrene instead of styrene
The reaction was carried out in the same manner as in Example 2 except that 74.6 mmol was used. As a result, 24.2 mmol of methyl p-methoxycinnamate and 13.3 mmol of dimethyl p-methoxyphenylsuccinate were produced. Example 12 p-chlorostyrene instead of styrene
The reaction was carried out in the same manner as in Example 2 except that 78.7 mmol was used. As a result, 23.9 mmol of methyl p-chlorocinnamate and 13.8 mmol of dimethyl p-chlorophenylsuccinate were produced. Example 13 2.7 mmol of lithium bromide instead of lithium chloride
The reaction was carried out in the same manner as in Example 9 except that . As a result, the styrene conversion rate was 80%, and 51 mmol of methyl cinnamate and 11 mmol of dimethyl phenylsuccinate were produced. Example 14 Example 9 except that 227 mmol of diisopropoxymethane was used instead of methyl orthoformate.
The reaction was carried out in the same manner. As a result, the amounts of isopropyl cinnamate and diisopropyl phenylsuccinate produced were 15 mmol and 6 mmol, respectively.

Claims (1)

[Claims] 1. In the presence of palladium, a halogen and a dehydrating agent, 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 represents hydrogen or an alkyl group having 1 to 6 carbon atoms. ) is an aliphatic alcohol having 1 to 4 carbon atoms,
General formula characterized by reaction with carbon monoxide and oxygen (wherein R ¹ and R ² are the same as defined above,
R ³ represents an alkyl group having 1 to 4 carbon atoms. )
A method for producing cinnamic acid esters shown in