JPH0571573B2 - - Google Patents

Description

[Detailed description of the invention]

a Industrial Application Field The present invention relates to 4,4'-diethyldiphenyl (hereinafter referred to as
4,4'-diphenyldicarboxylic acid (hereinafter referred to as DPDA) and/or monomethyl ester of DPDA (hereinafter referred to as DEDP) was brought into contact with molecular oxygen-containing gas in the presence of methanol in the liquid phase.
The present invention relates to a method for producing dimethyl ester (hereinafter referred to as DPDM) of DPMA) and/or DPDA (hereinafter referred to as DPDM). b Conventional technology DPDA is used as a copolymer component to produce fibers, films,
Used for plasticizers, resins, etc. Just as terephthalic acid or dimethyl terephthalate is used as a raw material for polyethylene terephthalate, DPDM can also be used as a raw material for a copolymerization component in the same way as DPDA. In particular, DPDM is an industrially superior compound compared to DPDA in that it can be handled as a liquid and can be purified by distillation and recrystallization. Both DPDA and DPMA can be easily converted into DPDM by applying known methylation methods, such as methyl esterifying terephthalic acid to dimethyl terephthalate. Many methods for synthesizing DPDA and DPDM are known (for example, see Kagaku to Kogyo Vol. 36, No. 12 (1983), pages 909-910). That is, 4,4'-
Dimethyldiphenyl, 4,4'-dicyclohexyldiphenyl, 4,4'-diacetyldiphenyl, p
- A method using chlorobenzoic acid, 2,2'-diphenyldicarboxylic acid, or a potassium salt thereof as a raw material is known. In addition to these raw materials, a method has also been proposed in which DPDM is obtained by oxidative coupling using methyl benzoate as a raw material and using a palladium catalyst. However, in the above-mentioned method, the raw materials etc. are extremely expensive, and the process for producing DPDA and DPDM is complicated, so that it is difficult to realize an industrially advantageous method. In particular, it is easy to infer that the process would be extremely complicated except for methods other than oxidizing the alkyl group at the 4,4' position of diphenyl to obtain DPDA or oxidizing and methyl esterifying it to obtain DPDM. DEDP is a raw material not mentioned above. This raw material can be easily synthesized, for example, by the method described in Japanese Patent Publication No. 49-39667. A possible method for obtaining DPDA through a simple oxidation reaction using DEDP as a raw material is to oxidize it with a molecular gas in a lower fatty acid solvent such as acetic acid in the presence of a heavy metal catalyst and a bromine compound as an accelerator. However, the equipment is severely corroded by bromine compounds, requires expensive materials such as titanium, and has short service life. On the other hand, a method of oxidizing with a molecular oxygen-containing gas in the presence of a heavy metal catalyst but without adding a bromine compound is also considered. Since this method does not use bromine compounds, there is almost no corrosion of the equipment, and even if the equipment is made of inexpensive materials such as stainless steel, it is estimated that the service life is long enough. It was extremely difficult to obtain the compound. c. Purpose of the Invention Therefore, the present inventors developed a DPDA that is effective for fibers, films, plasticizers, resins, etc. using DEDP as a raw material.
and/or a method for producing DPMA and/or DPDM, without using bromine compounds and using equipment made of inexpensive materials such as stainless steel.
The present invention was achieved as a result of intensive research into a method that can produce DPDM in high yield. d. Constitution of the Invention That is, the present invention provides a method for converting 4,4'-diethyldiphenyl into a manganese compound or a manganese compound in the absence of a bromine compound, without a solvent or in a solvent that is liquid under the reaction conditions. A method of oxidizing with a molecular oxygen-containing gas using either a compound and a cobalt compound or a manganese compound and a nickel compound as a catalyst, characterized in that the oxidation is carried out in the presence of methanol. - A method for producing diphenyldicarboxylic acid and/or its mono- and dimethyl ester. The present invention will be explained in more detail below. In the present invention, methanol supplied to the reaction system may be in liquid or gaseous form, or may be mixed with raw materials and solvents before being supplied. It is particularly preferred that methanol be continuously supplied and that unreacted methanol be continuously taken out of the reaction system. Although the effect of methanol can be recognized even if it is supplied in a very small amount, it is preferable to supply methanol at least 2 times the mole of raw material DEDP. Further, in the method of the present invention, substantially no solvent or a solvent that is inert to the reaction and exhibits a liquid state under the reaction conditions may be used. Here, "inert to reaction" means that it is not oxidized or oxidized/esterified. Furthermore, a compound produced by esterification or oxidative esterification under the reaction conditions may exhibit properties as a solvent under the reaction conditions. The term "liquid under reaction conditions" as mentioned above means that it is liquid under reaction temperature and reaction pressure. As these solvents, benzenes, carboxylic acid esters, etc. are used as solvents, and carboxylic acids, alkylbenzenes, etc. are used as those that react and act as a solvent. Further, solvents and the like may be used in combination.
When reacting without a solvent or using benzenes or carboxylic acid esters as a solvent, DPDM is mainly produced. Next, at least a manganese compound is used as a catalyst. Preferred manganese compounds include:
Particularly preferred organic acid salts are acetate, benzoate, toluate, naphthenate. The preferred concentration of the manganese compound is 10 ppm based on the total weight of DEDP and solvent in terms of metallic manganese.
As mentioned above, a particularly preferable concentration is 50 ppm or more. A more preferred catalyst system is a mixed catalyst system of a manganese compound and a cobalt compound. Preferred compounds for cobalt are organic acid salts like manganese compounds. The cobalt compound preferably has a ratio of 1:1 or more atoms to manganese in terms of metal. Another preferred catalyst system is a mixed catalyst system of a manganese compound and a nickel compound. Preferred nickel compounds are organic acid salts as well as manganese compounds. The ratio of the manganese compound to the nickel compound is preferably an atomic ratio of 1:0.5 to 1:10 in terms of metal. The reaction pressure is preferably in the range of normal pressure to 250 Kg/cm ² G as the total pressure, and in the range of 0.2 Kg/cm ² to 50 Kg/cm ² as the oxygen partial pressure ^. On the other hand, it is not preferable to make the total pressure higher than 250 kg/cm ² G because the device will be too large. Particularly preferable pressure is 0.2Kg/cm ² to 10 as oxygen partial pressure.
Kg/ ^cm2 . The molecular oxygen-containing gas used in the oxidation of the present invention may be a mixture of oxygen and an inert gas such as nitrogen, helium, argon, or carbon dioxide.
Air is easily available and economical. Next, the reaction temperature is preferably in the range of 200°C to 300°C. If the reaction temperature is too low, the reaction progresses very slowly; conversely, if the reaction temperature is too high, DPDA,
The yield of DPMA and DPDM decreases, and methanol loss increases, making it uneconomical. The method of the present invention will be described in detail below with reference to Examples and Comparative Examples. Examples 1 to 7 Raw material DEDP solvent and catalyst (acetate) were charged into a stainless steel autoclave with a capacity of 500 c.c. equipped with a reflux condenser, a stirrer, a gas inlet, and a methanol supply device, and the temperature was raised to the reaction temperature. After that, while stirring at high speed, blow in air so that the gas flow rate at the outlet is 1.0/min, and at the same time add liquid methanol to 90%
It was supplied at a rate of ml/Hr, and unreacted methanol was taken out together with the outlet gas. The components in the autoclave were analyzed and the results shown in Table 1 were obtained. Incidentally, no raw material remained in the reaction product.

[Table] Comparative Examples 1-2 An experiment was conducted in the same direction as in the example except that methanol was not supplied. The results are shown in Table-2.

【table】

[Table] e Effects of the invention As is clear from the above examples, according to the present invention, DEDP as a raw material is brought into contact with a molecular oxygen-containing gas in the presence of methanol and under a catalyst containing at least a manganese compound. with high yield
DPDA and/or DPMA and/or
It is possible to manufacture DPDM at low cost.

Claims (1)

[Scope of Claims] 1 4,4'-diethyldiphenyl is mixed with () a manganese compound or () a manganese compound and cobalt in the absence of a bromine compound, without a solvent or in a solvent that is liquid under the reaction conditions. 4,4'-diphenyl compound, or (4,4'-diphenyl) in a method of oxidizing with a molecular oxygen-containing gas using either a manganese compound and a nickel compound as a catalyst, characterized in that the oxidation is carried out in the presence of methanol. A method for producing dicarboxylic acid and/or its mono-dimethyl ester. 2 Oxidation of carboxylic acid esters, benzenes,
The manufacturing method according to claim 1, which is carried out using a solvent selected from the group consisting of carboxylic acids and alkylbenzenes. 3. The manufacturing method according to claim 1, wherein the oxidation is carried out at a temperature in the range of 200 to 300°C.