JPH0482868A - Production of dinitrile - Google Patents

Abstract

PURPOSE:To efficiently obtain the subject dinitrile by oxidizing an aromatic diamine in a tertiary amine solvent in the presence of a catalyst consisting of a cupric salt after addition of an inert solvent nonsolvent to the complex catalyst thereto, subsequently distilling off the tertiary amine, recovering a deposited catalyst and recycling the recovered catalyst. CONSTITUTION:An aromatic diamine having two mutually adjacent primary amino groups on an aromatic ring is oxidized using molecular oxygen in the presence of a complex catalyst composed of the amine, a cuprous salt and oxygen in a tertiary amine as the solvent for synthesis of a dinitrile after adding an inert solvent (e.g. hexane, cyclohexane or heptane) nonsolble of the complex catalyst and having a higher boiling point than that of the used tertiary amine to the reaction system. After completion of the reaction, excessive tertiary amine is distilled and recovered and the complex catalyst deposited in the distillation residue is filtered and recovered. The resultant dinitrile is then obtained from the filtrate and the recovered catalyst is recycled. The above- mentioned method is an effective method for recovery of the catalyst utilizing separation of the excessive tertiary amine.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to the oxidation of an aromatic diamine having two primary amine groups on its aromatic ring in the presence of a catalyst consisting of a tertiary amine and a cuprous salt. The present invention relates to a method of adding an inert solvent in which the complex catalyst is insoluble in a reaction, followed by separating the tertiary amine in which the complex catalyst is soluble by distillation, and recovering and reusing the precipitated complex catalyst.

Dinitriles are useful as pharmaceutical raw materials, industrial raw materials, and especially polymer raw materials.

[Prior art and problems to be solved by the invention] Conventionally, as a method for producing mucononitrile and its derivatives, 1,4-
A method of halogenating dicyano-2-butene followed by dehydrohalogenation (US Pat. No. 2,564,102), a method of decomposing aromatic diazide [Jhem, chem, Soc
, 87(5), 1147-8 (1965)), A method for aminating and oxidizing benzene with ammonia in the presence of a catalyst (US Pat. No. 3,579,559), Acrylonyl l-
Method for campling IJL in the presence of a catalyst (J, Or
ganomet, chem, 1978.152(2)
, 193-5), and methods for producing aromatic O-diamines by lead tetraacetate oxidation or nickel peroxide oxidation are known.

However, the oxidation of aromatic O-diamines with lead tetraacetate or nickel peroxide requires stoichiometric amounts of catalyst. Moreover, these methods have a yield of about 60%, so it is difficult to say that they are industrially preferred methods.

On the other hand, as a method for quantitatively producing mucononitrile from aromatic 0-diamine, a catalytic production method (Japanese Patent Publication No. 46 Sho. -5133). The publication states that after the completion of the reaction, most of the excess tertiary amine as a solvent is distilled off from the reaction system, and then the residue containing the catalyst and mucononitrile is treated with ether to extract mucononitrile into an ether layer. However, there is a description of a method for quantitatively obtaining the target product, mucononitrile.

The present inventors tried the reaction method described in the publication and found that although mucononitrile was obtained in high yield, the catalyst remaining as a residue during ether extraction became tar-like and adhered to the flask wall, and if left untreated, the catalyst could not be recovered. It is difficult to reuse the product, and this method cannot be called an industrial production method in terms of cost and reaction operability.

[Means to solve the problem]

In view of this situation, the present inventors conducted intensive studies on industrial production methods for midinitrile, and discovered a highly effective catalyst recovery method by adding an inert solvent and separating excess tertiary amine. It was completed.

That is, in the present invention, an aromatic diamine having two primary amino groups adjacent to each other on an aromatic nucleus is prepared using a tertiary amine as a solvent in the presence of a complex catalyst consisting of the amine, a cuprous salt, and oxygen. In the method of producing dinitrile by oxidation with molecular oxygen, an inert solvent that does not substantially dissolve the complex catalyst and has a boiling point higher than the tertiary amine used is added to the reaction system, After the completion of the reaction, the excess tertiary amine is recovered by distillation, and the complex catalyst precipitated in the distillation residue is recovered by filtration, and then di-1-lyl is separated from the filtrate. and a method for producing dinitrile in which the recovered catalyst is repeatedly used.

The reaction of the present invention, for example when using O-phenylenediamine as a starting material, is expressed as follows.

In the above reaction, a catalyst consisting of a tertiary amine and a cuprous salt is oxidized by oxygen to form an active barrel tertiary amine oxygen complex, which is thought to oxidize the diamine to produce a nitrile. .

By continuing to blow oxygen into the complex used in the reaction, it re-forms an active cupric tertiary amine oxygen complex and acts catalytically. However, since the complex is soluble in the tertiary amine that is the reaction solvent, it is difficult to recover it as it is.

The object of the process of the present invention is to provide an industrial method for producing dinitrile in which the complex is recovered in crystalline form after the reaction and is reused.

Examples of the tertiary amine used in the method of the present invention include trimethylamine, triethylamine, tripropylamine, tributylamine, triallylamine, pyridine,
Examples include 2-picoline, 3-picoline, quinoline, isoquinoline, morpholine, piperazine, and the like. Preferably pyridine is used. These may be used alone or in combination of two or more.

Examples of cuprous salts used in the method of the present invention include cuprous chloride, cuprous bromide, cuprous iodide, cuprous sulfate, and the like.

Although the ratio of tertiary amine and cuprous salt in the composition of the catalyst of the present invention is not particularly limited, it is usually at least one tertiary amine molecule per copper atom.

The aromatic diamine compound that is the starting material for the method of the present invention may have a primary amine bonded to an adjacent position on the aromatic nucleus, and a substituent may be bonded to another position on the aromatic nucleus. There is no problem.

Aromatic diamine compounds preferably used in the reaction of the present invention include 0-phenylenediamine, 0-toluenediamine, 3,4-dimedyl-10-phenylenediamine, 4
Examples include, but are not limited to, -chloro-0-phenylenediamine and 112diaminonaphthalene.

The method of the present invention will be explained below based on embodiments.

A cuprous salt is added to the above-mentioned tertiary amines, and oxygen is blown into the solution to form a complex consisting of the tertiary amine, cuprous salt, and oxygen. Next, an aromatic diamine compound is dissolved in a tertiary amine or an inert solvent and slowly added dropwise into the complex solution.

When the aromatic diamine compound solution is dropped into the complex solution, oxygen is continued to be blown into the complex solution, and the dropping rate of the aromatic diamine compound is adjusted so that the color of the complex remains green. After completion of the dropwise addition, an inert solvent in which the complex is insoluble is added to the reaction solution. However, the inert solvent may be added before the reaction, after the reaction, or during the reaction after dissolving the aromatic diamine compound to be added dropwise.

The reaction temperature is in the range of 10-80°C, preferably 20-40°C. The oxygen blowing rate is 0.1 to 10 j2 /min, preferably 0.1 to 10 j2 /min per mole of aromatic diamine.
It is 5 to 21/min.

The inert solvent to be added may be any solvent as long as it is inert to the complex and the reaction of the present invention and has no substantial solubility for the complex. Specifically, for example, hexane, cyclohexane, heptane, etc. , aliphatic hydrocarbons such as octane, nonane, and decane, and aromatic hydrocarbons such as benzene, toluene, xylene, trimethylhenzene, monochlorohenzene, dichlorohenzene, and tetralin.

The amount of the inert solvent to be added is 0.5 to 10 mff/mmole, preferably 1 to 3 mR/mmole, relative to the aromatic diamine as the raw material.

The inert solvent used in the method of the present invention has a boiling point of 10°C or more, preferably 20°C or more than the tertiary amine, since the tertiary amine is separated by distillation from the mixed solution containing the tertiary amine. You need to choose the expensive one.

Next, excess tertiary amine is removed from the reaction mixture by distillation, and when the distillation residue is cooled, a complex consisting of the cuprous salt and the tertiary amine precipitates out as crystals. The precipitated complex is separated by a conventional solid-liquid separation method.

As a specific method, vacuum filtration is often used. The separated and recovered complex can be used for subsequent reactions, and 2
The catalytic activity after the first time was similar to that of the first time. After distilling off the inert solvent from the filtrate, the target dinitriles can be obtained by performing a purification method such as reduced pressure/distillation or recrystallization.

〔Effect of the invention〕

According to the method of the present invention, the catalyst can be easily recovered and the recovered catalyst can be used for repeated reactions.1.
Dinitrile can be produced industrially with great advantage.

〔Example〕

Example 1 3.96 g of cuprous chloride was added to 100 ml of pyridine,
Stir while blowing oxygen at 100 m/min. The initially yellow solution turns dark green as oxygen is bubbled through and a complex is formed. After injecting oxygen for 1 hour, increase the oxygen to 100 mf.
While continuing to blow at a rate of f/min, a solution of 1.2.22 g of 3,4-diaminotoluene dissolved in pyridine was added dropwise so that the reaction solution remained dark green. After completion of the dropwise addition, 200 mf of xylene was added to the reaction solution, pyridine was distilled off, and the precipitated complex was filtered under reduced pressure. After washing the complex with n-hexane,
After drying under reduced pressure, 6.72 g of recovered complex was obtained. The filtrate was washed with 6N hydrochloric acid, neutralized with a saturated aqueous sodium bicarbonate solution, and then separated, and xylene was distilled off under reduced pressure to obtain 2-methyl-cis,
cis-mucononitrile 10.87g (purity 98.0%
, yield 90.2%). Melting point 52-54°C (literature value 53-54°C) The recovery rate of pyridine by the above operation was 98.3%.

6.72 g of the complex recovered in the above operation was used in place of the above cuprous chloride, and the same operation was performed two more times.The second time, 10.66 g of 2-methyl-cis, cis mucononitrile was (Purity 97.8%, yield 88.
3%) and 6.58 g of the recovered complex, and the third time, 9.77 g of 2-methyl-cis.cis-mucononitrile (
purity 97.8%, yield 79.5%) and the recovered complex was 5.9%
I got 2g.

Example 2 The same reaction as in Example 1 was repeated three times using 0-dichlorohenzene instead of xylene in Example 1.
The first time was 10.36 g of 2-medyru cis, cis-mucononitrile (purity 98.2%, yield 86.1%).
6.89g of recovered complex was obtained. The second time is 2-methyl-c
10.28g of iscis-mucononitrile (purity 9
860%, yield 85.3%) and 6.53 g of recovered complex was obtained. For the third time, 10.03 g of 2-methyl-cis, cis-mucononitrile (purity 97.2%, yield 82.5
%) and 6.52 g of recovered complex were obtained.

Example 3 The same reaction as in Example 1 was repeated three times using 1.2.4-)limethylhenzene instead of xylene in Example 1. In the first reaction, 2-methyl-cis, cis-mucononitrile was used with 10. 56g (purity 96.0%, yield 8
5.8%) and 6.72 g of recovered complex were obtained. 2- for the second time
Methyl-cis, cis-mucononitrile 10.32
g (purity 97.2%, yield 84.9%) and 6.23 g of recovered complex were obtained. The third time is 2-methyl-cis, cis
-10.10 g of -mucononitrile (purity 95.2%, yield 81.4%) and 5.98 g of recovered complex were obtained.

Comparative Example 1 A reaction was carried out in the same manner as in Example 1, and after the completion of dropping the pinodine solution of 3.4-) luenediamine, about 90% of the reaction solution was removed.
of pyridine was distilled off. Next, 200 d of ether was added to the residue to extract mucononitrile, and the ether extract was dried and concentrated to obtain 11.24 g of 2-medyl cis, cis-mucononitrile (purity 92.5%, yield 8
8%).

During the ether extraction, the complex remaining as an insoluble substance adhered to the flask wall, etc., and it was difficult to recover it as it was. In addition, the amount of pyridine distilled off by distillation is approximately 90% (if more is distilled off, the reactant will stick to the flask wall and be difficult to extract), and some of the complex remains in the ether layer. It happened.

Patent applicant Mitsui Toatsu Chemical Co., Ltd.

Claims (1)

[Claims] 1. An aromatic diamine having two primary amino groups adjacent to each other on an aromatic nucleus is prepared using a tertiary amine as a solvent, and a complex catalyst consisting of the amine, cuprous salt, and oxygen is prepared. In the method of producing dinitrile by oxidation with molecular oxygen in the presence of tertiary amine, an inert solvent that does not substantially dissolve the complex catalyst and has a boiling point higher than that of the tertiary amine used is used in the reaction system. and after the completion of the reaction, the excess tertiary amine is recovered by distillation, and the complex catalyst precipitated in the distillation residue is recovered by filtration, and then the dinitrile is separated from the filtrate. . 2. A method for producing dinitrile, in which the catalyst recovered by the method according to claim 1 is repeatedly used.