JPH0827067A - Production of dimethyl 2,6-decahydronaphthalenedicarboxylate - Google Patents

Abstract

PURPOSE:To obtain the subject compound by hydrogenation of dimethyl naphthalenedicarboxylate under relatively mild conditions. CONSTITUTION:This compound, dimethyl 2,6-decahydronaphthalenedicarboxylate, is obtained by hydrogenation of dimethyl 2,6-naphthalenedicarboxylate in a lower fatty acid ester plus saturated hydrocarbon as solvent in the presence of a palladium and/or rhodium reducing catalyst at 80-200 deg.C under a pressure of normal pressure to 30kg/cm<2>G.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to 2,6-decahydronaphthalenedicarboxylic acid dimethyl ester obtained by hydrogenating 2,6-naphthalenedicarboxylic acid dimethyl ester (hereinafter abbreviated as NDCE) to completely hydrogenate an aromatic ring. The present invention relates to a technique for synthesizing (hereinafter abbreviated as DDCE) under mild conditions with high yield.

[0002]

BACKGROUND OF THE INVENTION Polyalkylnaphthalene dicarboxylates derived from NDCE, especially polyethylene-
2,6-naphthalenedicarboxylate is superior to polyethylene terephthalate in heat resistance, mechanical properties and gas barrier properties, and is used as a highly functional material for fibers, films, bottles and industrial resins.

However, because of its high glass transition point, it is difficult to set molding conditions for bottles and the like. In addition, fluorescent coloration during bottle molding is also a problem. In order to solve this problem, DDCE has attracted attention as a polymer raw material or a modifier for polyethylene-2,6-naphthalene dicarboxylate. The present invention is this D
The present invention relates to a method of manufacturing DCE.

[0004]

2. Description of the Related Art As a method of manufacturing this DDCE, the following two means are already known. First, the method reported in US Pat. No. 3,534,002 uses NDCE of 35 to 700 Kg / cm ² at 0 to 200 ° C. (preferably 150 ° C.) in a cyclohexane solvent.
It is reacted with G (preferably 80 to 140 Kg / cm ² G) of hydrogen. Another report likewise uses about 120 Kg / cm ² G of hydrogen at 150 ° C. in cyclohexane solvent (GB 1024481). Not only is hydrogen used at a considerably high pressure in any of the methods, but also the diluents that can be used are narrowly limited, and therefore the danger of handling hydrogen under high pressure cannot be ignored. In addition, a pressure-resistant reactor and a high-pressure hydrogen booster are required, which increases operating costs and equipment costs, and is not an efficient method.

[0005]

[Means for Solving the Problems] Generally, when an alcohol solvent is used in a hydrogenation reaction and palladium or ruthenium is used as a catalyst, it is relatively low in the reaction of hydrogenating a naphthalene ring to a tetralin ring. Although it reacts sufficiently under hydrogen pressure, it is difficult to obtain decalin in high yield even under conditions of high temperature and high pressure when the hydrogenation is further carried out so that the target decalin is reacted.

The present inventor has conducted extensive studies in order to solve these problems, and as a result, by using lower fatty acid esters and saturated hydrocarbons as solvents, DDCE is synthesized under relatively low pressure conditions even with conventional catalysts. It was found that this was possible, and the present invention was reached and the problem was solved.

That is, according to the present invention, a lower fatty acid ester and a saturated hydrocarbon are used as a solvent for 2,6-naphthalenedicarboxylic acid dimethyl ester in the presence of at least one catalyst selected from the group consisting of palladium and rhodium. Used in the temperature range of 80-200 ℃, normal pressure-30Kg
A process for producing 2,6-decahydronaphthalenedicarboxylic acid dimethyl ester, which comprises reacting hydrogen under a pressure of / cm ² G.

The present invention will be described below.

The carrier for supporting the catalyst palladium and / or rhodium used in the present invention is generally used activated carbon, diatomaceous earth, alumina, zeolite, etc.,
The carrier is not particularly limited, but activated carbon having a relatively large surface area is preferable.

In the present invention, the reaction temperature for hydrogenating NDCE is preferably higher in order to allow the reaction to proceed completely, but is preferably in the range of 80 to 200 ° C., more preferably 130. ~ 170 ° C.

The solvent used in the present invention is not particularly limited as long as it is a saturated hydrocarbon solvent having low polarity or a lower fatty acid ester solvent such as ethyl acetate. The reaction does not proceed sufficiently with the use of a highly polar polar solvent such as methanol or acetic acid, and it is 2,6- (tetrahydronaphthalene) dicarboxylic acid dimethyl ester in which only one aromatic ring of the naphthalene ring is hydrogenated. The reaction tends to stop.

In the present invention, the hydrogen pressure for hydrogenating NDCE is not important, but from normal pressure to 30 Kg / cm.
^It is preferable to allow hydrogen to act at ² G (particularly 15 to 20 kg / cm ² G). The higher the pressure, the higher the reaction rate. However, if the pressure is too high, a rapid heat generation is accompanied, causing side reactions and decomposition reactions, and conversely a decrease in yield.

The weight ratio of NDCE to the solvent in the present invention is preferably such that NDCE is at least partially soluble, but there is no particular effect and the total amount of raw materials / total amount of solvent (weight ratio) = 0. It may be carried out in the range of 01 to 1.0.

In the present invention, the weight ratio of NDCE to the catalyst is not particularly limited. For example, when rhodium containing 5% by weight of activated carbon is used, the total catalyst (dry) including carrier / total raw material weight ratio =
It is preferably carried out in the range of 0.005 to 0.1.

As the hydrogenation method of the present invention, a so-called suspension bed method in which a hydrogenation catalyst is suspended in a solution is used, or a so-called fixed bed in which a hydrogenation catalyst is fixed and a solution is flown therein is used. The method 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 vessel. There is a way to blow. Further, for example, in a fixed bed, there is a method in which a solution in which NDCE as a raw material is completely dissolved and hydrogen gas are passed in a cocurrent flow in a bed (for example, a packed tower) packed with a hydrogenation catalyst. In that case, the result will not be affected even if any of these methods is used.

DDCE 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 solvent through distillation, and further distilling under reduced pressure.

[0017]

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.

[0018]

Example 1 In a Hastelloy autoclave with a stirrer having an internal volume of 500 cc, 30 g of a raw material NDCE was added 3 g of a catalyst (5% Rh-C) having commercially available rhodium supported on activated carbon together with 150 g of cyclohexane. I put it in. Next, the air in the autoclave was replaced with nitrogen, the nitrogen was replaced with hydrogen, the stirrer was started, the rotation speed was adjusted to 1000 rpm, the temperature was raised to 150 ° C over about 1 hour, and then the pressure in the autoclave was changed. 1
The temperature was raised to 5 Kg / cm ² G, and the temperature pressure was maintained for 2 hours while supplementing the hydrogen pressure with the absorption of hydrogen. After the hydrogen absorption was completed, the autoclave was cooled and the residual hydrogen was released. The product taken out from the autoclave was No. 5
It was filtered using a filter paper of C and about 30 g of cyclohexane was used to wash the catalyst on the filter paper. The separated filtrate of this product and the washed filtrate were combined, and then the solvent cyclohexane was distilled off using an evaporator to obtain about 32.3 g of a crude product. As a result of analysis of the composition, there was no residual raw material, and there was no intermediate in which the reaction was stopped at the tetralin ring. The target DDCE was obtained in a yield of about 95%.

Example 2 The method of Example 1 was repeated except that the reaction solvent was ethyl acetate. The results are shown in Table 1.

Example 3 The reaction vessel was a 3000 ml stainless steel autoclave, and the reaction pressure was 20.
The method of Example 1 was repeated except that it was Kg / cm ² G and the stirring speed was 700 rpm. The results are shown in Table 1.
Described in.

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

[Example 5] 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 1.

[0024]

[Table 1]

Comparative Example 1 The method of Example 1 was repeated except that the reaction solvent was methanol. The results are shown in Table 2.
Described in.

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

[0027]

[Table 2]

[0028]

According to the present invention, as compared with the conventional method,
By selectively limiting the solvent, the hydrogenation reaction pressure can be lowered, and the efficiency and safety in production can be significantly improved. Further, the selectivity of NDCE is also improved.

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

Claims (1)

[Claims] 1. A lower fatty acid ester and a saturated hydrocarbon are used as a solvent for 2,6-naphthalenedicarboxylic acid dimethyl ester in the presence of at least one catalyst selected from the group consisting of palladium and rhodium, 80
A method for producing 2,6-decahydronaphthalenedicarboxylic acid dimethyl ester by reacting hydrogen under a pressure of ˜200 ° C. and a normal pressure ˜30 Kg / cm ² G.