JP2000226359A - Production of high purity dimethyl trans-2,6- decahydronaphthalenedicarboxylate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for efficiently separating a transisomer from an isomeric mixture of a dimethyl 2,6-decahydronaphthalenedicarboxylate. SOLUTION: This method is to cool a cis-trans isomeric mixture of a dimethyl 2,6-decahydronaphthalenedicarboxylate so as to separate a crystallized dimethyl trans-2,6-decahydronaphthalenedicarboxylate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to cis-2,6-decahydronaphthalenedicarboxylic acid dimethyl ester (hereinafter referred to as cis-DDCE) and trans-2,6-
The present invention relates to a method for producing high-purity trans-DDCE from a mixture of decahydronaphthalenedicarboxylic acid dimethyl ester (hereinafter, referred to as trans-DDCE).

[0002]

2. Description of the Related Art High-purity trans-DDCE is converted into trans-2,6-decahydronaphthalenedimethanol as a polyester modifier or by further hydrogenating an ester group. It is important as a diol component of a polyester resin, a polyurethane resin, and a polycarbonate resin.

A method for producing 2,6-decahydronaphthalenedicarboxylic acid dimethyl ester is described in 2,6-
A method for catalytic reduction (hydrogenation) of naphthalenedicarboxylic acid dimethyl ester using a noble metal catalyst is known. JP-A-6-263860 discloses an example using a 5% platinum carbon catalyst. The reference discloses a method using palladium or rhodium as a catalyst.

[0004]

It is known that cis and trans isomers exist in decahydronaphthalene obtained by hydrogenating naphthalene depending on the configuration of the cross-linked carbon. 2,6-DDCE obtained by hydrogenating 2,6-naphthalenedicarboxylic acid dimethyl ester also produces the corresponding cis, trans isomer. JP-A-6-236860, JP-A-8-27067
There is no description on the formation of isomers in any of the above items, but the 2,6-DDCE obtained by any of the methods is used.
Is a mixture of cis, trans isomers.

When 2,6-DDCE is used as a raw material for a polymer material, the isomer purity of 2,6-DDCE is considered to greatly affect the physical properties of the polymer to be produced. In order to achieve this, it is necessary to obtain 2,6-DDCE with as high an isomer purity as possible. As a separation and purification method generally used in the chemical industry, there is a method by distillation. However, cis-DDCE and trans-D
Since the boiling point of DCE is very close, distillation at a high number of stages and a high reflux ratio is required, and cis-DDCE and trans-D
Separation of DCE by distillation is not easy and high purity tran
It was difficult to obtain s-DDCE. It is an object of the present invention to provide a mixture of tr-isomer mixture of cis and trans isomers of 2,6-decahydronaphthalenedicarboxylic acid dimethyl ester.
An object of the present invention is to provide a method for efficiently separating ans bodies.

[0006]

Means for Solving the Problems The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, have found that cis-DDCE
From the solid-liquid equilibrium of trans-DDCE,
High purity trans isomer can be separated from the isomer mixture of DDCE by crystallization separation, and high purity trans isomer can be easily obtained in one crystallization tank without the need for a high-stage distillation column or the like. As a result, the present invention has been completed. That is, the present invention relates to cis-2,6-decahydronaphthalenedicarboxylic acid dimethyl ester and trans-
The mixture of 2,6-decahydronaphthalenedicarboxylic acid dimethyl ester is cooled and crystallized to give trans-2,6.
-High purity trans-2,6 characterized by separating dimethyl ester of decahydronaphthalenedicarboxylic acid
-A process for producing dimethyl decahydronaphthalenedicarboxylate.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION cis-DD as a raw material of the present invention
A mixture of CE and trans-DDCE is usually produced by catalytic reduction of 2,6-naphthalenedicarboxylic acid dimethyl ester using a noble metal catalyst as described above. The cis-DDCE measured by the inventors and tra
FIG. 1 shows a solid-liquid equilibrium diagram of ns-DDCE. From this, the eutectic composition in this binary system was trans-DDCE of 4
3%, trans-DDCE in the DDCE mixture
It can be seen that if the concentration is 43% or more, trans-DDCE can be recovered as crystals by crystallization.

Cis-DDCE and trans-DDCE
Crystallization can be performed without using a solvent, but when a solvent is not used, the liquid component impregnated with crystals may be difficult to remove when separating precipitated crystals due to high viscosity of the liquid. To avoid this, an appropriate solvent can be used during crystallization to reduce the viscosity of the liquid. Any solvent may be used as long as it can dissolve DDCE crystals, and aliphatic hydrocarbons such as hexane, cyclohexane, heptane, nonane and decane are preferably used.

The processing temperature during the crystallization is slightly higher than the temperature at which the cis, trans-DDCE binary eutectic mixture precipitates in the system containing the solvent. If the treatment temperature is too high, the yield of trans-DDCE crystals to be precipitated is impaired, so that the treatment temperature is preferably closer to the binary eutectic precipitation temperature. Tra precipitated by crystallization
The crystals of ns-DDCE are separated by filtration, centrifugation, etc., but are not particularly limited to these methods, as long as they can separate solid and liquid.

[0010]

EXAMPLES The method of the present invention will be described below in detail with reference to examples. Note that the present invention is not limited to the scope of the following embodiments.

Example 1 cis-DDCE was 20.0% and trans-DDCE was 8
After heating 10 g of a mixture consisting of 0.0% to 80 ° C. to completely dissolve it, the mixture was cooled to 50 ° C. to separate crystals, and rinsed with heptane. As a result, cis-DDCE was 3%, trans
2.5 g of crystals having a 97% DDCE composition were obtained.

Example 2 cis-DDCE is 20.0% and trans-DDCE is 8
Mix 10 g of a mixture consisting of 0.0% with 90 g of heptane at 50 ° C
After heating and dissolving all, the mixture was cooled to 10 ° C. to separate crystals. As a result, cis-DDCE was 1%, trans-
4.2 g of crystals having a 99% DDCE composition were obtained.

[0013]

As is clear from the above examples, according to the present invention, high-purity cis-DDCE can be easily obtained from a cis, trans-DDCE mixture by one stage of crystallization. According to the present invention, a high-stage distillation column and the like are unnecessary,
The present invention is an industrially superior method since highly pure trans-DDCE can be efficiently recovered.

[Brief description of the drawings]

FIG. 1 is a solid-liquid equilibrium diagram of 2,6-decahydronaphthalenedicarboxylic acid dimethyl ester.

────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] February 5, 1999 (1999.2.5)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0013

[Correction method] Change

[Correction contents]

[0013]

As is clear from the above examples, according to the present invention, high purity trans- DDCE can be easily obtained from the cis, trans-DDCE mixture by one step of crystallization. According to the present invention, a distillation column having a high number of stages is not required, and high-purity trans-DDCE can be efficiently recovered. Therefore, the present invention is an industrially superior method.

Continued on the front page (72) Inventor Minoru Takakawa 22nd Wadai, Tsukuba-city, Ibaraki Pref. F-term in Mitsubishi Gas Chemical Co., Ltd. General Research Laboratory 4H006 AA02 AC11 AD15 BB11 BC51

Claims (2)

[Claims] 1. A mixture of cis-2,6-decahydronaphthalenedicarboxylic acid dimethyl ester and trans-2,6-decahydronaphthalenedicarboxylic acid dimethyl ester is cooled and crystallized to give trans-2,6-decahydronaphthalenedicarboxylic acid. A method for producing high-purity trans-2,6-decahydronaphthalenedicarboxylic acid dimethyl ester, comprising separating dimethyl acid ester. 2. The method according to claim 1, wherein the crystallization is carried out using a solvent.