JPS6169746A - Production of tetramethyl biphenyltetracarboxylate - Google Patents

Abstract

PURPOSE:The titled compound is produced by the dehydrogenative dimerization reaction of dimethyl o-phthalate in the presence of a catalyst and oxygen, and the distilled and recovered unreacted DMP is refined under a specific condition and a reused as the raw material of the above reaction. CONSTITUTION:Tetramethyl biphenyltetracarboxylate is produced by the dehydrogenative dimerization of dimethyl o-phthalate (DMP) in the presence of a Pd-containing catalyst and oxygen at 50-300 deg.C. The reaction mixture is distilled, and the obtained unreacted DMP is purified by washing with an alkaline aqueous solution or contacting with a basic ion exchange resin, etc. until the content of phthalic acid and/or phthalic anhydride having nearly the same boiling point as DMP is decreased to <=1,000ppm, preferably <=50ppm. The purified DMP is reused as the raw material.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for producing tetramethyl biphenyltetracarboxylate (hereinafter referred to as BTCM).

Conventional technology BTCM is an intermediate of biphenyltetracarboxylic dianhydride, which is a raw material for polyimide resin, and dimethyl ortho-phthalate (hereinafter referred to as DMP) is processed as a base solvent in the presence of oxygen using a palladium-containing catalyst. Among them, a method of producing ψμ by carrying out a dehydrogenation trimerization reaction is known (
Special public ++A4tl-10641 etc.). In this BTCM manufacturing method, the reaction rate of ]JMP is 10
Since the diameter is extremely low at approximately 20φ, a large amount of unreacted DMP remains in the mixture after the reaction.

After the reaction, D M P rt in the mixture: usually,
DMP is distilled and recovered by distillation, and the recovered DMP is reused as a raw material for the above reaction.

[Problem that the invention seeks to solve]

However, it was found that the reaction result was significantly reduced to 1 luG when the DMP subjected to the first round was used as a raw material for the above reaction as it was. When carrying out the above reaction using recovered DMP as a raw material, in a batch reaction the reaction conditions need to be at a higher level compared to the initial conditions, and in a continuous reaction, if the reaction conditions are kept constant, the reaction will not occur. Since the content would deteriorate, it could not be realistically adopted.

The present invention uses phthalic acid (hereinafter referred to as phthalic acid), which has almost the same boiling point as the DMP produced during the reaction or distillation, by subjecting the recovered DMP to a dehydrogenation dimerization reaction.

(hereinafter referred to as PHA) and/or phthalic anhydride (hereinafter referred to as PAN)
We discovered that these components contained a small amount of DM and that these components had an adverse effect on the dehydrogenation reaction.
The object of the present invention is achieved by reusing P after refining the content of PHA and PAN in P to below a certain value.

[Means for solving problems]

The present invention relates to a method for producing BTOλ by subjecting DMP to -#-...O dehydrogenation reaction in the presence of oxygen using a palladium-containing catalyst. Reaction DMP with PHA and/or PA
The gist of the present invention is a method for producing BTCM, which is characterized in that it is purified until the N content becomes 1)000 PP or less, and then reused as a raw material for the reaction.

The manufacturing method of BTCM targeted by the present invention includes D M
P in the presence of oxygen using a palladium-containing catalyst 0009
This is a method for producing BTCM2-y7 through a 0-dehydrogen trimerization reaction. The palladium-containing catalyst may be, for example, an organic acid salt of palladium such as palladium acetate, or may be used in combination with an acid binder such as sodium acetate, cesium acetate or potassium acetate, and acetic anhydride. No problem. The amount of palladium catalyst used is usually p, o, i to ioo millimoles per mole of DMP.

The reaction temperature is usually 60°C to 300°C, and the reaction pressure is usually 1 to 3 o ky / as oxygen partial pressure.
It is cA. Although this reaction needs to be carried out in the presence of oxygen, it is usually desirable to carry out the reaction while supplying air to the liquid layer of the reactor.

Since the mixture after the reaction contains a large amount of unreacted DMP, it is necessary to recover and reuse it. Unreacted DMP can be easily recovered by distilling the reaction mixture. In other words/
The boiling point of DMP at TOrr is 100°C, and the boiling point of the produced BTOM is 0. Use J Torr
Since the temperatures are i and 0°C, the two can be easily separated.

Although the reaction mixture may be subsequently processed, this recovery distillation of unreacted DMP is preferably carried out after separating the palladium catalyst contained in the reaction mixture. Separation of palladium catalysts is usually performed by heating the reaction mixture at 200 °C.
The palladium component is precipitated as palladium black in a hydrogen gas atmosphere, and then this is heated to -
This can be done by following the steps below.

The residue obtained by recovering unreacted DMP from the mixture after the reaction contains the target product BTOM. This is usually recovered by crystallizing the entire residue in an organic solvent such as methanol to precipitate BTcyyz crystals, and passing the crystals through one sieve, according to a known method.

In the present invention, when the recovered unreacted DMP is reused as a raw material for the above-mentioned trimerization reaction, the PH contained in DMP is
A and/or PAN content / 000 PPm
Below, TNT jji:l is preferably reduced to /00 PPm or less, more preferably J' o PPm or less.
It is an essential requirement that it be processed. In short, 1 DMP recovered by normal methods always contains o, i-2
, o'ra! % of PHA and/or PAN, and if this is reused as it is as a raw material for the trimerization reaction, the reaction results will be significantly deteriorated. Therefore, if the content of PHA and/or PAN in the recovered DMP is higher than the above range, it is unsuitable as a raw material for the Nikeika reaction.

The methods for purifying the recovered DMP include washing the DMP with an aqueous alkaline solution, or contacting the DMP with a basic ion exchange resin, and further purifying the DMP with an adsorbent such as molecular cyrus or high porous resin. Examples include a method of contact treatment. Examples of the alkali in the case of washing with an aqueous alkali solution include ammonia, ethylamine, n-propylamine, primary or secondary aliphatic amines such as diethylamine, caustic potash, potassium carbonate, etc. Among them, ammonia is preferred. . In this case, the concentration of the aqueous solution is usually 0.1 in the case of ammonia water.
~20% by weight, and the amount of alkaline aqueous solution used is usually 0.5% by weight based on DMP. / -,? 0 times the capacity. Furthermore, DMP washed with an alkaline aqueous solution is usually washed with a dilute aqueous mineral acid solution such as hydrochloric acid or sulfuric acid.
Washing with water is particularly desirable. On the other hand, as the basic ion exchange resin, commercially available), ebolus type, porous type, or gel type resins are usually used.

DMP whose PHA and/or PAN content has been reduced to /000 PPm or less by the above-described treatment is reused as a raw material for the above trimerization reaction.

There is no problem in using it.

[Function] The present invention provides for the use of phthalic acid (hereinafter referred to as PH
A) and/or phthalic anhydride (hereinafter referred to as PAN) were found to have a negative effect on the dehydrogenation dimerization reaction. As a result of studies based on knowledge, the object of the present invention can be achieved by reusing the recovered DMP after refining the content of PHA and PAN to a certain value or less.

[Example] Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to the following Examples.

Examples 1 to 3 and Comparative Example 1-2 (First reaction) Equipped with a stirrer and a temperature controller/! DMP (industrial reagent) 1062 in a θOml flow-through reactor? and as a catalyst palladium acetate, atop, potassium carbonate o, t≠7
2. Charge acetic acid 3, rμ2, pressurize the system with air, and make the oxygen partial pressure 2 kp / (-i, then increase the air / J
120℃ while feeding into the liquid at Ot-/hr.
After raising the temperature to , add a mixture of l:/(volume ratio) of acetic acid! ml
/ hr Shitsuka Soehara! A time reaction was performed. The production rate of BTOM in this reaction was 73 mol.

After the reaction, the mixture was reacted in a hydrogen gas atmosphere at /λO° C. for to minutes to reduce palladium, and then the precipitated palladium black was separated.

This mixture was then heated under a reduced pressure of / ij
Unreacted DMP is removed by distillation at a temperature of ♂3
09 was distilled out. When the content of PHA and PAN contained in this distilled DMP was measured, the total amount was about A I700 PPm.

On the other hand, the residue is methanol/27.1)-f! to)
Luen 7,! ', 7 mixed with a mixed solvent of f-! Crystals of f) B T q y were precipitated by cooling and crystallizing at a temperature of 0.degree. C., and the P was separated and collected.

(Purification of DMP) The DMP recovered by the above method was processed according to the method shown below, and fN-1! PHA and PA in subsequent DMP
When the N content was measured, it was found as shown in Table 1.

Table 1 (Note) Purification method: 0 Example/(Ammonia water washing) D M P 30 with /% ammonia water of 0.3 times the total volume
Wash by stirring for 30 minutes at a temperature of °C, then o:j
After washing with twice the volume of 1% hydrochloric acid and water, 130℃
The mixture was dehydrated by bubbling nitrogen gas at /t/m1n for to minutes under heating.

0 Example λ (amine aqueous solution cleaning) In Example 1, 3% n-propylamine was used instead of aqueous ammonia p.

0 Example 3 (Basic ion exchange resin treatment) Fya, Diaion HPA2j) was added, stirred at a temperature of 50°C for 10 minutes, the resin was separated, and the above operation was repeated twice. Ta.

Comparative example/(water washing) D? , (P is 0.3 times the volume of water at a temperature of 30°C.
It was washed by stirring for a minute.

(Second reaction) Using each DMPj3/f subjected to the above caustic treatment as a raw material, the same reaction as in the first reaction of Upper NIS (1 time,
The production rate of BTCM when the dehydration reaction of DMP was carried out on the scale //'2) was determined, and the results shown in Table 1 were obtained.

・"α2 table reference: The production rate of BTOM in the first reaction is 7
．． It was T morchi.

〔Effect of the invention〕

According to the present invention, even if unreacted DMP recovered from the DMP dehydrogenation process is recycled and used, the dual-purpose reaction is not inhibited.

The effect of the present invention is that trace amounts of PHA and/or PAN are
This was obtained through the discovery that P has an adverse effect on the dehydrogenation reaction.

Sender: Mitsubishi Chemical Industries, Ltd. Representative Patent Attorney Hase - Others/names Procedure 1) 3 length (voluntary) 6 Contents of amendment Corrected to 2.080$J.

Claims (5)

[Claims] (1) In a method for producing tetramethyl biphenyltetracarboxylate by subjecting dimethyl ortho-phthalate to a dehydrogenation reaction in the presence of oxygen using a palladium-containing catalyst, the unused material recovered by distilling the mixture after the reaction. Tetramethyl biphenyltetracarboxylate, characterized in that the reacted dimethyl ortho-phthalate is purified until the content of phthalic acid and/or phthalic anhydride is /1000 ppm or less, and then reused as a raw material for the reaction. manufacturing method. (2) The method for producing tetramethyl biphenyltetracarboxylate according to claim (1), wherein the purification treatment is a method of treating recovered dimethyl ortho-phthalate with a basic ion exchange resin. (3) The method for producing tetramethyl biphenyltetracarboxylate according to claim (1), wherein the purification treatment is a method of washing the recovered dimethyl ortho-phthalate with an aqueous alkaline solution. (4) The method for producing tetramethyl biphenyltetracarboxylate according to claim (3), wherein the alkaline aqueous solution is a method in which recovered dimethyl ortho-phthalate is washed with aqueous ammonia. (5) Biphenyltetracarboxylic acid according to claim (3), wherein the alkaline aqueous solution is a method in which recovered dimethyl ortho-phthalate is washed with an aqueous solution of a primary or secondary aliphatic amine. Production method of tetramethyl.