JPH0529376B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a method for producing phenylacetaldehyde. Phenylacetaldehyde is used as a fragrance material.
It is also an important substance as an intermediate for medicines, agricultural chemicals, and amino acids. [Prior Art] Various methods for producing phenylacetaldehyde have been known. For example, in Japanese Patent Publication No. 55-31128, benzyl halide was monomerized under a high pressure of 200 kg/cm ² using acetone as a solvent and coexisting an N-dialkyl-substituted acid amide in the presence of dicobalt octacarbonyl as a catalyst. Yield by reacting with carbon oxide and hydrogen
Phenylacetaldehyde was obtained at 52.2%. In addition, in a similar reaction, a method using a two-layer solvent of water and an organic solvent immiscible with water (Japanese Patent Publication No. 1983-
No. 43455), using acetonitrile as a solvent, under pressure in the presence of an alkali metal or alkaline earth metal.
Method of reaction at 100Kg/ ^cm2 (Special Publication No. 56-113727
There is also a method in which benzyl halide and carbon monoxide are reacted in alcohol using a cobalt tetracarbonyl anion as a catalyst to obtain phenyl acetate and phenylacetaldehyde (Japanese Patent Application Laid-open No. 59-93020). However, all of these methods use relatively expensive solvents and expensive cobalt catalysts under high pressures of 100 to 200 Kg/cm ² , so they have many disadvantages from an industrial perspective and are not fully satisfactory. It wasn't something I could do. On the other hand, some of the present inventors have conducted research with the aim of developing a complex catalyst that exhibits enhanced catalytic activity when the complex catalyst is combined with light irradiation, and using aromatic hydrocarbons as raw material compounds. ,
We have found a method of converting this into the corresponding aldehyde, alcohol, etc. by direct carbonylation reaction (Japanese Patent Application No. 230620/1982). [Problems to be Solved by the Invention] However, in this method, for example, when benzene is directly subjected to a carbonylation reaction treatment under light irradiation using benzene as a raw material compound, it can be converted into the corresponding benzaldehyde, benzyl alcohol, benzoic acid, etc. , when toluene is used as a raw material compound, tolualdehyde in which the aromatic ring is directly carbonylated,
Only a trace amount of phenylacetaldehyde, which was converted into methylbenzyl alcohol and the like and whose side chain substituted with an aromatic ring was carbonylated, was produced. [Means for Solving the Problems] Therefore, the present inventors conducted intensive studies to solve these problems, and found that when the reaction was carried out under light irradiation of a specific wavelength, the side chain of the aromatic ring became carbonyl. The present invention was achieved by discovering that That is, an object of the present invention is to provide a method for efficiently producing phenylacetaldehyde by carrying out a carbonylation reaction directly under light irradiation. This objective is easily achieved by a method for producing phenylacetaldehyde, which is characterized by reacting toluene and carbon monoxide in the presence of a rhodium compound and under irradiation with light in a wavelength range of 325 nm or more. The present invention will be explained in more detail below. The rhodium compound used in the present invention is not particularly limited, but it is preferable to use a compound that is at least partially solubilized during the reaction from the viewpoint of improving the reaction rate. As these compounds, complexes containing organic ligands are particularly preferably used. Examples of these include rhodium carbonyl, chlorodicarbonyl rhodium dimer, acetoacetatodicarbonyl rhodium, chloro(1,5-hexadiene) rhodium dimer, chlorobis(ethylene) rhodium dimer, and the general formula RhXL ₃ (X is a halogen atom, L is phosphine, phossuinite, phosphonite,
or a ligand selected from phosphites),
RhX(CO)L ₂ (X and L are the same as above), HRh
(CO)L ₃ (L is the same as above), or HRh(CO) ₂ L ₂
Examples include, but are not limited to, complexes represented by (L is the same as above). Moreover, these rhodium compounds may be used not alone, but two or more types may be used in combination, and furthermore, it is also included in an advantageous embodiment of the present invention that the above-mentioned ligand L is added together with the rhodium compound. Specific examples of the ligand L include triphenylphosphine, trimethylphosphine, tributylphosphine, methyl dimethylphosphine, dimethyl methylphosphine, trimethylphosphite, and the like. In addition, in the toluene carbonylation reaction of the present invention, the presence of the above-mentioned rhodium compound and irradiation with light of a specific wavelength are essential, and the wavelength range is 325 nm or more, preferably 325 nm to 400 nm.
It is important to use light with a wavelength of . The light in this wavelength range is a commonly used mercury lamp,
By attaching a filter or a monochromator to the xenon lamp to cut out wavelengths outside the above range, it is possible to adjust the light to a specific wavelength. In the carbonylation reaction of the present invention, the reaction temperature is not particularly limited, and may be carried out by heating to about 250°C in order to improve the reaction rate, but it is usually carried out at 0 to 200°C. Good. It is not always necessary to use a single carbon monoxide, and it may be used together with an inert gas that does not affect the reaction. At that time, the pressure of carbon monoxide is not particularly limited, and is usually
It is preferable to conduct the reaction at a temperature of 0.1 to 300 atm, preferably 0.5 to 100 atm. In the reaction of the present invention, toluene, which is a reaction substrate, is usually used as a solvent, but if necessary, a compound that is less likely to be carbonylated than toluene, such as cyclohexane, decalin, benzonitrile parafluorobenzene, etc., may be used as a solvent. You can also do it. Separation and recovery of the product after the completion of the reaction is easily carried out by methods such as rectification, recrystallization, or chromatography after removing toluene, or toluene and the solvent, etc., by separation means such as distillation. [Examples] Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to the following Examples unless the gist thereof is exceeded. Example 1 Toluene solution of chlorocarbonylbis(trimethylphosphine)rhodium (0.7mM, 2ml)
A 1 cm square container made of Pyrex was placed in the container, the pressure was reduced, and carbon monoxide was introduced several times. An external irradiation type 500W high-pressure mercury lamp was used as the light source, and a filter was attached to the light source so that the wavelength region of the irradiated light was 325 nm or more, and the mixture was stirred at room temperature for 6 hours while being irradiated with light. After adding β-methylnaphthalene as an internal standard, the product was analyzed by gas chromatography to quantify the product. Table 1 shows the results.

[Table] Comparative example of molar yield 1 Toluene solution of chlorocarbonylbis(trimethylphosphine)rhodium (0.7mM, 2ml)
The mixture was placed in a 1 cm square container made by Pyrex, the pressure was reduced, and carbon monoxide was introduced several times. The light source was an external irradiation type 500W high-pressure mercury lamp, and a filter was attached to the light source so that the wavelength range of the irradiated light was 295 to 420 nm.
Stir for hours. After adding β-methylnaphthalene as an internal standard, gas chromatography analysis revealed that no phenylacetaldehyde was produced. Table 2 shows the results.

[Table] Yield [Effects of the Invention] According to the present invention, phenylacetaldehyde can be easily obtained from inexpensive toluene and carbon monoxide by carrying out a carbonylation reaction under irradiation with light of a specific wavelength. Therefore, its industrial significance is great.

Claims (1)

[Claims] 1. A method for producing phenylacetaldehyde, which comprises reacting toluene and carbon monoxide in the presence of a rhodium compound and under irradiation with light in a wavelength range of 325 nm or more.