JPH0237331B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing alkylphenols by reacting phenols and alcohols in the presence of a catalyst consisting of a metal compound containing phenolates and/or alcoholates. Alkylphenols, especially the orthoalkylated product 2,6-xylenol, are important not only as raw materials for the production of polyphenylene ether (PPE), a useful plastic, but also as resins, plasticizers, antioxidants, and sterilizers. It is a well-known compound as a raw material for agents and agricultural chemicals. As a method for alkylating phenols, aluminum oxide, magnesium oxide, manganese oxide, iron oxide, chromium oxide, zeolite, etc., as well as various other components added thereto, are used as catalysts to convert phenols and alcohols. Although catalytic reaction methods are known, all of these catalysts have problems in terms of activity, selectivity, induction period, lifespan, etc. when considering the overall performance of the catalyst, so it is difficult to say that they are sufficient catalysts. It's tough. In order to solve these problems, the present inventors used a metal compound containing phenolates and/or alcoholates as a catalyst. We found that improvements could be made and arrived at the method of the present invention. That is, the present invention provides a method for producing alkylphenols using alcohols and phenols having at least one hydrogen atom on an aromatic ring, in which a metal compound containing phenolates and/or alcoholates is used as a catalyst. This is a characteristic method for producing alkylphenols. The phenols used in the method of the present invention are phenol compounds having one or more hydrogen atoms on the aromatic ring, and have the general formula (In the formula, R ₁ to _{R 5} are hydrogen, a hydrocarbon, a hydroxyl group, or an unsubstituted or substituted aromatic hydrocarbon group such as phenyl or naphthyl, at least one of which is a hydrogen atom.) It will be done. Examples of such compounds include phenols, cresols, xylenols, trimethylphenols, various ethylphenols, n-, iso-, and tert-butylphenols,
Examples include phenylphenols and naphthylphenols. Similarly, phenol compounds in which one or more different functional groups are substituted on the aromatic ring can also be used. The alcohols used in the present invention are:
A lower alcohol having 1 to 4 carbon atoms, such as methanol, ethanol, n-propanol, iso-propanol, n-butanol, iso-
Butanol, tert-butanol, etc. Methods for preparing phenolates and alcoholates used in the method of the present invention include 1. A method of reacting a metal with a phenol or an alcohol. 2. A method of reacting a metal oxide or hydroxide with a phenol or an alcohol. 3 Method of reacting metal halides with phenols or alcohols 4 Method of reacting phenolates or alcoholates with other types of phenols or alcohols 5 Method of reacting phenolates or alcoholates with esters (ester exchange), etc. will be selected from among the The metal component elements in the phenolates and/or alcoholates used in the catalyst include alkali metals, alkaline earth metals, earth elements, and transition elements, among which magnesium, aluminum,
Calcium, manganese, iron, and chromium are good, and in the case of magnesium in particular, when used in the production of alkylphenols, it improves catalytic activity, improves ortho-selectivity, and extends catalyst life by lowering the reaction temperature, which is much better than conventional catalysts. It has high performance. The phenolates and/or alcoholates can be used as they are after being made into a suitable shape and strength by a conventional granulation method, or they can be used by being impregnated with a metal oxide carrier, coated, or mixed. As the metal oxide carrier, common catalyst carriers such as alumina, silica, magnesia, titania, and zirconia can be used. The catalyst can be activated in a nitrogen stream, in a reaction gas, in hydrogen gas, in an inert gas, or under a reducing atmosphere.
30 minutes at a temperature of 100-600℃, preferably 150-550℃
It will be conducted for 100 hours. The method for producing an alkylphenol is carried out at a reaction temperature of 300 to 600°C, preferably 350 to 540°C, and a reaction pressure of usually under increased pressure or normal pressure, although it can be carried out at atmospheric pressure or lower. In order to obtain the highest yields of alkylated products, at least 1 mol, preferably 2 to 4 mol of alcohol is used per hydrogen atom on the phenol to be alkylated. For example, when it is desired to obtain 2,6-xylenol in high yield by methylating phenol with methanol, it is desirable to use 4 to 8 moles of methanol per mole of phenol. The raw material is preferably supplied to the reaction system at a liquid hourly space velocity of 0.2 to 10 hr ^-1 , and generally, it is appropriate to supply the raw material to the side where the liquid hourly space velocity is large at a high reaction temperature, and to the side where the liquid hourly space velocity is small at a low temperature. When supplying raw materials, it is also possible to entrain an inert gas such as nitrogen, or a reducing gas such as hydrogen or carbon monoxide. In particular, by coexisting water, the life of the catalyst can be extended and the selectivity can be improved. The reaction may be carried out in a fixed bed, fluidized bed or moving bed, but a multi-tube fixed bed method is common. Although the theoretical explanation for the effectiveness of phenolates and alcoholates has not yet been fully elucidated, they are effective in improving catalytic activity and, in particular, selectivity, by increasing the number of catalytic active sites and making the activity intensity uniform. considered to be a thing. The present invention will be explained below with reference to Examples, but the present invention is not limited to the contents of these Examples. In addition, in the present examples and comparative examples, the catalyst performance is shown by the conversion rate and the 2,6-xylenol selectivity, and each is defined by the following formula. Conversion rate (mol%) ≡ Phenol conversion rate (mol%) = (
1-Amount of unreacted phenol (mol)/Amount of phenol supplied (
mol)) x 100 2,6-xylenol selectivity (phenol basis) = 2,6-xylenol production amount (mol)/supplied phenol amount (mol) - unreacted phenol amount (mol) x 100 2,6-xylenol selection Rate (based on methanol) = 2 x 2,6-xylenol production amount (mol) / supplied methanol amount (mol) - unreacted methanol amount (mol) x 10
0 In addition, in Examples 4 and 5, a reaction was carried out to methylate m-cresol. Example 1 80 g of commercially available magnesium oxide powder calcined at 550°C and 282 g of phenol were placed in a ball mill and mixed at 150°C for 16 hours, and then the phenol was sufficiently removed under vacuum to obtain magnesium phenolate.
This was pressure molded, sized and used as a catalyst. The reactor used for alkylation consisted of a phenol and methanol supply pump, a raw material liquid vaporizer, a quartz glass reactor, a product vapor condensation section,
It starts from the receiver. 10-16 in the center of the reactor
After filling 20ml of the catalyst mentioned above and placing it in an electric furnace, the temperature of the catalyst bed was set to 500℃ and the liquid hourly space velocity was set to 500℃.
Phenol, methanol and water (supplied molar ratio 1:5:1.7) were fed at 1.65 hr ^-1 to carry out a reaction for the purpose of producing 2,6-xylenol. The results are shown in Table 1.

[Table] Comparative Example The reaction was carried out in the same manner as in Example 1, except that magnesium oxide was used instead of magnesium phenolate as a catalyst. The results are shown in Table 2.

[Table] Example 2 0.5 g of iodine in 300 ml of sufficiently dehydrated methanol
While keeping the temperature at 50° C., 36.5 g of magnesium metal pieces were gradually added to the mixture to prevent sudden generation of hydrogen, and after the generation of hydrogen had stopped, reflux was carried out for 3 hours. Following cooling, methanol was evaporated at 40° C. for 5 hours using a rotary evaporator to obtain magnesium methylate. A mixture of 48.5 g of magnesium methylate and 105 g of phenol was suspended in 150 ml of n-heptane, and the n-heptane was refluxed at 98°C for 10 hours, cooled, and the heptane and methanol were evaporated off using a rotary evaporator. 110 g of enolate was obtained. Take 10g of this powder, mix well with 90g of magnesium oxide powder, pressurize and mold, then granulate into 10-16 meshes.
ml was used as a catalyst for methylation of phenol.
The molar ratio of phenol to methanol and water to be supplied is 1:5:1.7, the liquid hourly space velocity is 1.85hr ^-1 , and the reaction temperature is
The reaction was carried out at 490°C. The results are shown in Table 3.

[Table] Example 3 Magnesium methylate 48.5g and magnesium phenolate 56.0g synthesized by the same method as Example 2
After thoroughly mixing g in a mortar and molding under pressure,
The particles were sized to 16 mesh, and 20 ml of the particles was used as a catalyst for the reaction. 1:5 parts of phenol, methanol and water
The reaction was carried out at a molar ratio of 1.7, a liquid hourly space velocity of 1.65 hr ^-1 and a reaction temperature of 490°C. The results are shown in Table 4.

[Table] Example 4 204 g of aluminum isopropoxide was added to 282 g of phenol, and the mixture was refluxed under a nitrogen atmosphere for 10 hours. Following cooling, isopropanol was removed under reduced pressure to obtain 214 g of aluminum phenolate. 10g of aluminum phenolate and powdered magnesia
After thoroughly mixing 40 g, pressure molding and sizing into 10 to 16 meshes, 20 ml was used as a catalyst. m-
When raw materials with a molar ratio of cresol and methanol of 1:5 were reacted at a liquid hourly space velocity of 1.65 hr ^-1 and a reaction temperature of 490°C, the conversion rate of m-cresol was 99%.
The selectivity of 2,3,6-trimethylphenol is 97
It was %. Example 5 20 g of aluminum phenolate synthesized in the same manner as in Example 4 and 30 g of powdered silica were thoroughly mixed, pressure molded, and then sized into 10 to 16 meshes.
was applied to the catalyst. A raw material containing m-cresol and methanol in a molar ratio of 1:5 has a liquid hourly space velocity of 1.04 hr ^-1 ,
When the reaction was carried out at a reaction temperature of 450 DEG C., the conversion rate of m-cresol was 92% and the selectivity of 2,3,6-trimethylphenol was 87%.

Claims (1)

[Claims] 1. A catalyst containing magnesium or aluminum phenolates and/or alcohols as a catalyst in a method for producing alkylphenols by reacting phenols having at least one hydrogen atom on an aromatic ring with alcohols. A method for producing alkylphenols, characterized by using.