JPH083116A - Production of methyl p-hydroxymethylzenzoate - Google Patents

Abstract

PURPOSE:To produce the methyl p-hydroxymethylbenzoate by reducing methyl p-formylbenzoate under a mild condition. CONSTITUTION:Methyl p-formylbenzoate ester is reduced in the presence of a catalyst containing ruthenium in at least one kind of solvent selected from a group consisting of an alkyl alcohol, cyclohexane and a lower fatty acid ester at room temperature to 200 deg.C under a pressure of ordinary pressure to 30kg/cm<2> to produce the methyl p-hydroxymethylbenzoate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention hydrogenates p-formylbenzoic acid methyl ester (hereinafter abbreviated as MFB) to give p-formylbenzoic acid methyl ester.
Hydroxymethyl benzoic acid methyl ester (hereinafter MHM
(Abbreviated as B)) under mild conditions with good yield.

Since MHMB can be used as a starting material for a polycondensation product, it can be used as a raw material for synthetic fibers and synthetic resins and also as a raw material for pharmaceuticals and the like.

[0003]

2. Description of the Related Art Conventionally, p-hydroxymethylbenzoic acid ester has halogenated and hydrolyzed p-toluic acid,
It can be produced by a method of subsequent esterification, a method of electrochemical reduction of dimethyl terephthalate (West German Patent Publication No. 2428878), but these methods have a low yield in the former case. In addition, the latter case is not efficient because of high manufacturing cost.

As the synthetic method by catalytic hydrogenation, terephthalic acid is used as a catalyst in a water solvent using rhenium oxide as a catalyst.
A method of reacting at 0 ° C. (US Pat. No. 4,448,987) has been reported, but the reaction pressure is 100 Kg.
It is not industrially used because it has a high conversion rate of 20% / cm ² G, a conversion rate of 20% and a low selectivity rate of 85%.

On the other hand, in the method by selective hydrogenation of p-formylbenzoic acid ester, reduction of aldehyde group to methyl group has been a problem. A method (Patent Publication No. 55-395) for solving this problem by using palladium as a catalyst or a copper chromite catalyst at low temperature and low pressure has been reported, but palladium was used. In some cases, in practice, even at a sufficiently low temperature and low pressure, a reaction in which an aldehyde is reduced to a methyl group without stopping at a hydroxyl group proceeds at a considerable rate. (Refer to Comparative Examples 1 and 2) When a copper chromite catalyst is used, on the contrary, a considerably high temperature and high pressure are required, and an increase in by-products due to the high temperature is also observed.

In addition, various studies have been conducted. Generally, in the hydrogen reduction of aromatic aldehydes, a catalyst containing copper or chromium or a catalyst containing zirconium oxide is used to react at high temperature and high pressure in order to suppress side reactions. There are many examples.

However, the reaction at high temperature and high pressure cannot be said to be an efficient manufacturing method because a pressure resistant reactor and a hydrogen booster for high pressure are required, resulting in large operating costs and equipment costs.

[0008]

When a catalytic hydrogenation reaction is used and a palladium catalyst is used, it is possible to carry out the reaction under conditions where the reaction temperature and the reaction pressure are considerably low. The reduction to the methyl group also occurs. Even if rhodium or rhenium is used instead of palladium, a reaction product having a methyl group is present at the same time as when palladium is used, and at the same time, the reaction yield is lowered.

[0009]

[Means for Solving the Problems] The present inventors have conducted extensive studies to solve these problems, and by using ruthenium as a catalyst, alcohols of aldehydes can be obtained by catalytic hydrogenation reaction while suppressing side reactions. The present invention has been completed by finding out a method of reducing to.

The hydrogenation reaction in the present invention is also effective for the hydrogen reduction reaction of other aromatic aldehydes.

That is, according to the present invention, p-formyl benzoic acid methyl ester is converted into C-containing C in the presence of a catalyst containing ruthenium.
Any one of 1 to C4 alcohol, lower fatty acid and cyclohexane is used as a solvent, and room temperature to 200 ° C. and normal pressure to 3
A method for producing methyl ester of p-hydroxymethylbenzoic acid, which is characterized by reacting hydrogen under a pressure of 0 Kg / cm ² G.

The present invention will be described in detail below.

The carrier that supports the catalyst ruthenium used in the present invention is generally used activated carbon, diatomaceous earth, alumina, silica, titania, magnesia, zeolite, etc., and the carrier is not limited at all, Activated carbon with a large surface area is preferred.

In the present invention, the reaction temperature for hydrogenating MFB is not particularly limited as long as it does not exceed the temperature at which MFB decomposes, but it is usually room temperature to 200 ° C., preferably 30 to 150 ° C. Particularly preferred.

The solvent used in the present invention is important, it must be inert to the hydrogenation reaction, and care must be exercised because the by-products generated differ depending on the solvent used. In particular, when methanol is used as the solvent, dimethyl acetal produced by the reaction of the aldehyde group and methanol is produced, and the production ratio thereof remarkably differs depending on the temperature. Tertiary butanol is the reaction rate, conversion rate,
The selectivity is relatively high and preferred.

In the present invention, the hydrogen pressure in hydrogenating MFB is not so important and is about 60 Kg / cm.
If it is ² G or less, there is no particular increase in by-products or impurities, but normally atmospheric pressure to 30 Kg / cm ²
It is preferable that hydrogen acts on G. The composition of the recovered reaction product does not depend on the pressure, and the higher the pressure, the larger the reaction rate. Therefore, industrially, the composition is 10 to 30 Kg / cm ² G.
Is the best.

The weight ratio of MFB and solvent in the present invention is preferably such that MFB is at least partially soluble, and the total weight ratio of raw materials / total weight ratio of solvents = 0.01 to 1.0. Preferably.

In the present invention, the weight ratio of the catalyst to MFB is not particularly limited. For example, when a catalyst containing ruthenium in an amount of 5% by weight of activated carbon is used, the total catalyst weight (dry) including the carrier / total raw material weight ratio is It is preferable to carry out in the range of 0.005 to 0.1.

The hydrogenation method of the present invention is usually a so-called suspension bed method in which a hydrogenation catalyst is suspended in a solution, or a so-called fixed bed in which a hydrogenation catalyst is fixed and a solution is flown through it. The method of can be adopted. Further, for example, in a suspension bed, a method of charging a hydrogenation catalyst, a raw material and a solvent into a pressure vessel, replacing the space with hydrogen, and then stirring at a predetermined temperature for a predetermined time, or by introducing hydrogen gas into a reaction solution. There is a way to blow. Further, for example, in a fixed bed, there is a method in which a solution in which MFB as a raw material is completely dissolved and hydrogen gas are allowed to flow in parallel with each other in a bed filled with a hydrogenation catalyst (for example, a packed tower). In the case of using any of these methods, there is almost no difference in the result.

MHMB obtained by hydrogenation by the method of the present invention
The composition can be purified by removing the catalyst by filtration, completely removing the catalyst and the solvent through distillation, and further distilled and recrystallized.

[0021]

EXAMPLES Next, the present invention will be described in more detail by way of examples. The conversion rate and selectivity in the following examples are calculated based on the following formulas.

[0022]

[Equation 1]

Example 1 15 g of raw material MFB was placed in a Hastelloy autoclave with an internal volume of 500 cc and equipped with a stirrer, and commercially available ruthenium was supported on activated carbon (5% Ru-C) 1 g, 140 g of a third catalyst It was added with butanol. Next, the air in the autoclave was replaced with nitrogen, the nitrogen was replaced with hydrogen, and then the stirrer was started, the rotation speed was adjusted to 1000 rpm, and the temperature was raised to 80 ° C over about 40 minutes. 20
The state was maintained for 0.5 hours while raising the pressure to Kg / cm ² G and supplementing the hydrogen pressure with the absorption of hydrogen. Then, although the absorption of hydrogen was stopped, the state was maintained for another 0.5 hour, and then the autoclave was cooled to release hydrogen. The product taken out from the autoclave was No. It was filtered using a 5C filter paper, and the catalyst on the filter paper was washed with about 30 g of tert-butanol. After the separated filtrate and the washed filtrate of this product were combined, the solvent tert-butanol was removed using an evaporator to obtain about 15.1 g of a composition organism. As a result of analyzing the composition, only the target MHMB was contained except that the residual raw material and impurities including terephthalic acid monomethyl ester were all contained in an amount of about 6.0% by weight.
The MHMB selectivity was 94.4%.

Example 2 The method of Example 1 was repeated except that the reaction temperature was 110 ° C. The results are shown in Table 1.
It was shown to.

[Example 3] The reaction pressure was 40 kg / cm ^2.
The method of Example 1 was repeated except that it was G. The results are shown in Table 1.

Example 4 The method of Example 1 was repeated except that the reaction solvent was ethyl acetate. The results are shown in Table 1.

[0027]

[Table 1]

Examples 5 to 8 The method of Example 1 was repeated except that the reaction solvent was methanol and the reaction temperature. The results are shown in Table 2.

[0029]

[Table 2]

Comparative Example 1 The method of Example 1 was repeated except that the catalyst was a catalyst in which palladium was supported on activated carbon (5% Pd-C). The results are shown in Table 3.

[Comparative Example 2] The method of Example 1 was repeated except that the catalyst was a catalyst in which palladium was supported on activated carbon (5% Pd-C) and the reaction temperature was 45 ° C. The results are shown in Table 3.

[0032]

[Table 3]

[0033]

According to the present invention, as compared with the conventional method,
The target MHMB can be produced more selectively, the hydrogenation reaction pressure can be lowered, and the efficiency and safety in production are significantly improved. In addition, since the reaction conditions are fairly wide, the operation during production is extremely easy, and the amount of impurities is small, so that purification can be easily performed.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Mitsuhito Aoyagi 77, Kitayoshida-cho, Matsuyama-shi, Ehime Teijin Limited Matsuyama Office

Claims (2)

[Claims] 1. A p-formylbenzoic acid methyl ester in the presence of a catalyst containing ruthenium, an alkyl alcohol,
Room temperature to 200 using at least one solvent selected from the group consisting of cyclohexane and lower fatty acid ester.
A method for producing p-hydroxymethylbenzoic acid methyl ester by reacting hydrogen under a pressure of 30 ° C. and atmospheric pressure to 30 Kg / cm ² G. 2. The method according to claim 1, wherein the alkyl alcohol has 1 to 4 carbon atoms.