JP3210148B2 - Method for hydrogenating dialkyl naphthalenedicarboxylate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technology for synthesizing a dialkyl tetralin dicarboxylate (hereinafter abbreviated as TDCE) by hydrogenating a dialkyl naphthalene dicarboxylate (hereinafter abbreviated as NDCE).

[0002]

BACKGROUND OF THE INVENTION Poly (alkylene naphthalenedicarboxylate) derived from NDCE, especially poly (ethylene-2,6-naphthalenedicarboxylate), has higher heat resistance, mechanical properties and gaseous properties than poly (ethylene terephthalate). It has excellent barrier properties and is used as a highly functional material for fibers, films, bottles and industrial resins. However, since the glass transition point is high, it is difficult to set molding processing conditions for, for example, bottles. To solve the problem, TDCE is used as a polymer raw material or poly (ethylene-2,6-naphthalenedicarboxylate).
Has attracted attention as a modifier. The present invention uses this TDCE
And a method for producing the same.

[0003]

2. Description of the Related Art The following two methods are known as methods for synthesizing TDCE. First, JP-A-51-
The method disclosed in Japanese Patent No. 127058 is a method in which 1-tetralone-3,7-dicarboxylic acid or its alkyl ester is hydrogenated to obtain tetralin-2,6-dicarboxylic acid or its 2,6-alkyl ester. .

Further, US Pat. No. 3,534,002 discloses that 2,6-naphthalenedicarboxylic acid dialkyl ester (hereinafter abbreviated as 2,6-NDCE) is hydrogenated in the presence of a nickel catalyst to give tetralin-2,6 A method for obtaining a dialkyl dicarboxylate (hereinafter abbreviated as 2,6-TDCE) is described.

In consideration of the above two measures, the former technique is a synthesis method that requires several steps to obtain the starting tetralone dicarboxylic acid or its alkyl ester. Anyway, if available, it is not an industrially advantageous synthesis method. The latter means for synthesizing is about 35-70 using a nickel catalyst.
Since 2,6-NDCE is hydrogenated under high pressure of 0 kg / cm ² G, the danger of handling hydrogen under high pressure cannot be ignored, and the yield of the product is not satisfactory. Therefore, the purification efficiency is low and the economy is low.

[0006]

SUMMARY OF THE INVENTION Since the activity of nickel catalyst is low, in order to hydrogenate NDCE to obtain TDCE, the reaction pressure should be about 35 to 700 kg / cm ² G, and actually 100 kg / cm ² G. As described above, the reaction temperature was set to 150 ° C.
Although it is necessary to do above, the point of handling hydrogen under high pressure,
While safety issues remain, excessive hydrogenation reaction to dialkyl decalin dicarboxylate is difficult to avoid, resulting in a decrease in yield. On the other hand, palladium, ruthenium, and rhodium have been known as catalysts for synthesizing dialkyl decalin dicarboxylate by hydrogenating NDCE because of their high hydrogenation activity, but as catalysts for obtaining TDCE by partially hydrogenating, (J. Chem. En)
g. Data, 14 (4), 489-90 and GB 1024441).

The inventor has set out to solve these problems.
As a result of intensive studies, the present inventors have reached the present invention and have solved the problem.

That is, the present invention uses a solvent which is at least partially soluble in NDCE under the reaction conditions in the presence of at least one catalyst selected from the group consisting of palladium, ruthenium, rhodium and platinum. Then, hydrogen is acted at a hydrogen pressure of 35 kg / cm ² G or less to synthesize a dialkyl tetralin dicarboxylate, thereby hydrogenating a dialkyl naphthalenedicarboxylate.

The present invention will be described below.

The position of NDCE in the present invention is not limited as long as it is a di-substituted product.
The present invention can be advantageously carried out if 2,6-NDCE available as a raw material for 6-naphthalenedicarboxylate) can be used.

The NDCE in the present invention is a dialkyl ester, and specific examples include a dimethyl ester, a diethyl ester and a diisopropyl ester. Further, these monoalkyl esters can also be used as a raw material in the present invention, and the present invention can be carried out using an available dimethyl ester.

The carrier for supporting the catalyst palladium, ruthenium, rhodium or platinum used in the present invention is generally used activated carbon, diatomaceous earth, alumina, silica, titania, magnesium, zeolite and the like, and the carrier is not limited at all. Activated carbon having a relatively large specific surface area is preferred.

[0013] The solvent used in the present invention is not particularly limited as long as it is inert to the hydrogenation reaction. A solvent in which NDCE is at least partially soluble under hydrogenation reaction conditions, and specific examples include acetic acid, methanol, ethanol, isopropanol, cyclohexane and the like.

In the present invention, the hydrogen pressure at the time of hydrogenating NDCE is important, and it is necessary to apply hydrogen at 35 kg / cm ² G or less. Particularly preferably, 5
To 35 kg / cm ² G, and the hydrogen pressure is 35 kg / cm ² G.
If it exceeds cm ² G, excessive hydrogenation reaction to decalin dicarboxylic acid or dialkyl decalin dicarboxylate proceeds, and the yield of TDCE decreases. Even if it is less than 5 kg / cm ² G, there is no particular problem, but the reaction rate decreases, and the reaction requires a long time, which is not preferable when the reaction is performed on an industrial scale.

[0015] The application temperature of the hydrogenation reaction of NDCE in the present invention is 0 to 150 ° C. Preferably 50 to 120
When the temperature exceeds 150 ° C., the excess hydrogenation to dialkyl decalin dicarboxylate proceeds, and the yield of TDCE decreases. Even if the temperature is lower than 50 ° C., there is no particular problem, but the reaction rate is lowered, and the reaction requires a long time, which is not preferable when the reaction is carried out on an industrial scale.

In the present invention, the weight ratio of NDCE to the solvent is preferably such that NDCE is at least partially soluble, and the weight ratio of the total amount of raw materials / the total amount of solvent is in the range of 0.01 to 1.0. Good to do.

In the present invention, the weight ratio of the catalyst to NDCE is not particularly limited. For example, in the case of any one of palladium, ruthenium, rhodium and platinum containing 5% by weight in activated carbon, the catalyst including the carrier Total amount / total weight ratio of raw materials = 0.005
It is preferable to carry out in the range of 0.5 to 0.5. If this value is less than 0.005, the reaction time becomes longer and it is not efficient.
When it exceeds, the excess hydrogenation reaction to the dialkyl decalin dicarboxylate proceeds, and the yield of TDCE decreases.

As the hydrogenation reaction method of the present invention, a method using a so-called suspended bed in which a hydrogenation catalyst is suspended in a solution,
Alternatively, an ordinary method using a so-called fixed bed in which a hydrogenation catalyst is fixed and a solution is passed through the fixed catalyst can be adopted. Further, for example, in a suspension bed, a hydrogenation catalyst and NDC as a raw material
After charging E and a solvent and replacing the space with hydrogen, there is a method of stirring at a predetermined temperature for a predetermined time, or a method of blowing hydrogen gas into the reaction solution. Further, for example, in a fixed bed, there is a method in which a solution in which the raw material NDCE is completely dissolved in a solvent and a hydrogen gas are passed in parallel to a layer (for example, a packed tower) packed with a hydrogenation catalyst. Can use any of these methods.

TDCE obtained by hydrogenation according to the method of the present invention
The crude product can be purified by removing the catalyst by filtration, removing the catalyst completely by distillation, and then recrystallizing the solvent or melting. For example, 2,6-TDCE (dimethyl ester) can be distilled at 208 ° C. under a reduced pressure of 10 mmHg. Furthermore, the crude 2,6-
Since TDCE has a low impurity content, it can be easily purified to a purity of 99.9% or more by recrystallization from methanol.

[0020]

According to the present invention, as compared with the conventional method, the hydrogenation reaction pressure of NDCE can be greatly reduced, and the efficiency and safety in production are greatly improved. Further, ND
Since the hydrogenation reaction temperature of CE can be lowered, the reaction proceeds gently and side reactions can be controlled, and the selectivity to TDCE is greatly improved.

[0021]

Next, the present invention will be described in more detail with reference to examples. The 2,6-NDCE conversion and the 2,6-TDCE selectivity in the following examples were calculated based on the following equations.

[0022]

(Equation 1)

[0023]

Example 1 10 g of raw material 2,6-NDCE (dimethyl ester, purity 99.9% or more) was charged to an internal volume of 500 cc.
Of in a stirred Hastelloy autoclave, the catalysts 2g of a commercially available 5% palladium was responsible lifting the activated carbon 10
Charged with 0 g acetic acid. Next, after replacing the air in the autoclave with nitrogen and further replacing nitrogen with hydrogen,
The autoclave was pressurized with hydrogen to 5 kg / cm ² G.
Next, start the stirrer and adjust the rotation speed to 500 rpm.
After the internal temperature of the autoclave was raised to 80 ° C. over 20 minutes, the internal pressure of the autoclave was raised to 10 kg / cm ² with hydrogen, and the state was maintained for 60 minutes. Then, since the absorption of hydrogen was lost, the autoclave was cooled to release hydrogen. The product taken out of the autoclave was analyzed by gas chromatography to confirm that the raw materials were completely consumed. The mixture was filtered at 50 ° C. using a 5C filter paper, and the catalyst on the filter paper was washed with 100 g of acetic acid at 50 ° C. After combining the separated filtrate and the washing filtrate of this product,
The solvent acetic acid was evaporated by an evaporator to obtain 10.1 g of a crude product. As a result of analyzing the composition, the target compound 2, except that it contained 1.40% by weight of all geometric isomers of dimethyl 2,6-decalin dicarboxylate (hereinafter abbreviated as 2,6-DDCE), was added. It was only 6-TDCE (dimethyl ester). The selectivity for this 2,6-TDCE (dimethyl ester) was 98.6 mol%.

[0024]

Examples 2 to 4 The procedure of Example 1 was repeated except for the amount of the starting materials 2,6-NDCE and the amount of the catalyst having 5% palladium supported on activated carbon. The results are shown in Table 1.

[0025]

[Table 1]

[0026]

As Example 5-7] catalysts, 5% ruthenium supported on activated carbon catalyst, <br/> except that the supported catalyst and 5% platinum on activated carbon 5% rhodium was catalysts carried on active carbon The method of Example 1 was repeated. The results are shown in Table 2.

[0027]

[Table 2]

[0028]

Example 8 solvent is except that it is methanol The method of Example 1 was repeated. The results are shown in Table 3.

[0029]

Example 9 except that the solvent is methanol was repeated process of Example 4. The results are shown in Table 3 together with Example 8.

[0030]

Comparative Example 1 The procedure of Example 8 was repeated except that the catalyst was a commercially available Raney nickel catalyst. The results are shown in Table 3 together with Examples 8 and 9 . All Ku hydrogenation reaction did not occur.

[0031]

[Table 3]

[0032]

Comparative Example 2 The catalyst was a commercially available Raney nickel catalyst, the reaction temperature was 150 ° C., and the reaction pressure was 105 kg / cm.
It is except that it is ² G was repeated process of Example 8. As a result, it was found that 2,6-DDCE contained 9.5% by weight in a combined amount of all geometric isomers, and the raw material 2,6-NDCE was contained.
1.0% remained. At this time, the selectivity of 2,6-TDCE was 91.3%.

[0033]

EXAMPLE 10 270 g of a raw material 2,6-NDCE (dimethyl ester, purity 99.9% or more) was added to an internal volume of 300.
In a 0 cc Hastelloy autoclave equipped with a stirrer, 18 g of a commercially available catalyst carrying 5% palladium on activated carbon was used.
And 900 g of methanol, and reacted under the same conditions as in Example 1. Most of the catalyst was removed by filtration, and the solvent was evaporated to obtain 273 g of a crude product. As a result of analyzing the composition, it was confirmed that the target compound 2 was obtained except that 2,6-DDCE contained 1.94% by weight in a combined amount of all geometric isomers.
It was only 6-TDCE (dimethyl ester). The selectivity of this 2,6-TDCE (dimethyl ester) was 98.1 mol%.

The crude product was distilled in a distillation apparatus equipped with a 20 cm Vigreux column under the conditions of a top pressure of 10 mmHg, a top temperature of 208 ° C., and a distillation pot temperature of 220 ° C., and 266 g (distillation rate: 97.4%) ) Was obtained. Further, 500 g of methanol was added to 250 g of the distilled product, heated to 55 ° C., cooled to 5 ° C., and the precipitated crystals were separated by filtration. Further, after washing with 200 g of methanol at 5 ° C., it was vacuum-dried at room temperature to obtain 225 g (recovery rate 90%) of 2,6-TDCE having a purity of 99.92%.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-7-53458 (JP, A) JP-A-6-199705 (JP, A) JP-A-6-157406 (JP, A) JP-A-51- 125265 (JP, A) JP 47-12320 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C07C 67/303 C07C 69/74 C07C 69/75 C07C 69/753 C07C 69/76 C07B 61/00 300 B01J 23/40

Claims (2)

(57) [Claims] 1. A palladium, ruthenium, in the presence of at least one catalyst selected from the group consisting of rhodium and platinum, naphthalene dicarboxylic acid dialkyl esters, naphthalene dicarboxylic acid diaryl Te reaction conditions odor
Even alkyl ester is no less using a solvent which is partially soluble, hydrogenation of naphthalene dicarboxylic acid dialkyl ester which comprises synthesizing tetralindicarboxylic acid dialkyl ester by the action of hydrogen under a pressure of less than 35 kg / cm ² G Method. 2. The method according to claim 1, wherein the alkyl naphthalenedicarboxylate is 2,2.
2. A dialkyl 6-naphthalenedicarboxylate.
The hydrogenation method according to 1.