JPH0739376B2 - Method for producing dinitrodiphenyl ethers - Google Patents

Description

TECHNICAL FIELD The present invention relates to an improved method for producing dinitrodiphenyl ethers. More specifically, dichlorodiphenyl ethers characterized by subjecting 4-chloronidrobenzene and nitrophenols to a condensation reaction in the presence of a dehydrochlorinating agent in the absence of a solvent using polyethylene glycol and its lower alkyl ethers as a catalyst. Manufacturing method.

The dinitrodiphenyl ethers are intermediates of diaminodiphenyl ethers which are raw materials for polyamide, polyamideimide and polyimide.

(Prior Art) Dinitrodiphenyl ethers have been conventionally produced by a condensation reaction of various halogenonitrobenzenes and nitrophenols.

For example, as a method of condensing without a solvent, 4-fluoronitrobenzene and 4-nitrophenol potassium salt are used.
The Ullmann reaction produced 4,4′-dinitrodiphenyl ether in 85% yield (MJ Rarick et al., J. Am. Chem. Soc.,
55 1290 (1933)) and yielded 2,4 'from 4-bromonitrobenzene and 2-nitrophenol potassium salt in a yield of 10%.
-Dinitrophenyl ether is produced (Igawa et al., Pharmaceutical Journal., 79 273 (1959)).

As a method of condensation using a solvent, various dinitrodiphenyl ethers have been produced using an aprotic polar solvent such as N, N-dimethylformamide or dimethylsulfoxide.

For example, 4-chloronitrobenzene and 3-nitrophenol potassium salt are condensed in an N, N-dimethylformamide solvent to give 3,4'-dinitrodiphenyl ether in a yield of 7
Manufactured at 3% (JJ Randall et al., J. Org. Chem., 27 40
98-4101 (1962)).

(Problems to be Solved by the Invention) However, among these methods, the method performed without a solvent generally requires the use of halogen-substituted nitrobenzene such as fluorine or bromine, which has high reaction activity but is expensive. However, the reaction is extremely difficult due to the low activity of inexpensive chlorine-substituted nitrobenzene (MJRarick
Et al., J. Am. Chem. Soc., 55 1289 (1933)).

However, Ullm using these chlorine-substituted nitrobenzenes
As an example of the ann reaction, 4-chloronitrobenzene and 4-
4,4'-Dinitrodiphenyl ether has been produced from nitrophenol and 2,2'-dinitrodiphenyl ether has been produced from 2-chloronitrobenzene and 2-nitrophenol (Tomita et al., Pharmaceutical Journal, 75 1079-1080).

In these production examples, the reaction temperature is extremely high at 230 to 240 ° C., the yield is not described, and the details are unknown, but as described by MJ Rarick et al., The reaction is extremely difficult, so it is extremely low. It is expected that the yield will be low.

Further, it is known that the method of carrying out without a solvent causes a rapid reaction and causes a danger. For this reason, it is necessary to carefully control the reaction temperature while maintaining it stepwise even when it is manufactured in a laboratory. Therefore, this method has the serious drawback that it is not suitable for mass production.

Further, since this method uses a copper compound such as copper powder as a catalyst, it is obviously disadvantageous that the purification of the target product requires an extremely complicated operation.

On the other hand, in the method using a solvent, since a relatively expensive solvent is used, it has to be recovered.

In addition, this method generally has a relatively good selectivity of reaction, but produces an azoxy compound which is difficult to separate from the target substance in addition to a high molecular weight substance as a by-product.

Furthermore, when a solvent such as dimethyl sulfoxide is used, even if a trace amount of these solvents remains in the target substance, the target substance is catalytically reduced to poison and deteriorate the noble metal-based catalyst when producing diaminodiphenyl ethers. It is known to end up. Therefore, this method has drawbacks such as great expense and labor required for recovery of the solvent and purification of the desired product.

(Means for Solving the Problem) The present inventors have diligently studied a method that is inexpensive and can be industrially manufactured without these drawbacks. as a result,
The present inventors have completed the present invention by finding that the condensation reaction of 4-chloronitrobenzene and nitrophenols can be carried out in the absence of a solvent when polyethylene glycols are used as a catalyst.

That is, the present invention provides a method for producing dinitrodiphenyl ethers, which comprises subjecting 4-chloronitrobenzene and nitrophenols to condensation reaction in the presence of a dehydrochlorinating agent using polyethylene glycol or a lower alkyl ether thereof as a catalyst. is there.

According to the method of the present invention, 3,4'-dinitrodiphenyl ether and 4,4'-dinitrodiphenyl ether can be produced.

As this raw material, 4-chloronitrobenzene and nitrophenols are 3-nitrophenol and 4-nitrophenol. The reaction between these chloronitrobenzenes and nitrophenols may be carried out in a stoichiometric amount or any excess amount.

In the case of polyethylene glycol as the catalyst used,
It can be used as long as it has an average molecular weight of 200 or more, but when industrially used, it is preferable to use an inexpensive, liquid to low melting point having an average molecular weight of 400 to 1000.

The lower alkyl ether of polyethylene glycol generally has 4 to 12 ethylene oxide units. These include tetraethylene glycol dimethyl ether, tetraethylene glycol diethyl ether, octaethylene glycol dimethyl ether, etc., polyethylene glycol dimethyl ether, polyethylene glycol diethyl ether. Mixtures such as ether are also used.

The upper limit of the amount of these catalysts used is not specified as long as it is 1 wt% or more with respect to all raw materials.
A wt% range is preferred.

The dehydrochlorination agent (hereinafter referred to as a base) used in the method of the present invention is an alkali metal carbonate, hydrogen carbonate, hydroxide or alkoxide, and specifically, potassium carbonate, sodium carbonate, carbonic acid. Potassium hydrogen, potassium hydroxide, sodium hydroxide, potassium isopropoxide,
Examples include bases such as sodium isopropoxide. It suffices that the amount of these bases used is equivalent to or more than the nitrophenol, and specifically, the range of 1 to 3 equivalents is sufficient.

The method of the present invention is carried out substantially without solvent, but in order to remove water in the system, it may be carried out by adding a small amount of an azeotropic dehydration solvent such as benzene, toluene, xylene, chlorobenzene, etc. good. The reaction temperature is from about the melting point of the target compound to above it. I.e. 100
To 240 ° C, preferably 130 to 200 ° C.

As a general embodiment of the present invention, the above-mentioned base is added to a predetermined amount of chloronitrobenzene and nitrophenol, and a catalytic amount of polyethylene glycol or the like, and the reaction is carried out at a predetermined temperature while passing an inert gas such as nitrogen gas as it is. Alternatively, either an alkali metal salt of nitrophenol is obtained in advance, and this is reacted with chloronitrobenzene in the presence of a catalyst such as polyethylene glycol. The progress of the reaction can be known by thin layer chromatography or high performance liquid chromatography.

After the completion of the reaction, post-treatment is carried out depending on the purpose of use, but in most cases the intended product can be obtained selectively, so in many cases discharging it as it is and pulverizing will meet the purpose of use. Further, if necessary, it may be washed with water or purified by recrystallization with a solvent or the like to improve the quality.

(Operation and Effect) The method of the present invention is also characterized in that dinitrodiphenyl ethers can be produced with high purity and high yield, and that there is little coloration due to generation of by-products.

Further, since no solvent is used, labor and cost for recovery, etc. are not required, and not only is it economical because the volumetric efficiency of the device is extremely large, but the progress of the reaction can be achieved by conventionally known solventless methods. Compared with this, it is possible to proceed gently at a low temperature, which is suitable for industrial implementation.

(Example) Hereinafter, the method of the present invention will be described in more detail with reference to Examples.

Example 1. A reactor equipped with a stirrer and a thermometer was charged with 47.3 g (0.3 mol) of 4-chloronitrobenzene and 11.7 g of polyethylene glycol having an average molecular weight of 1000, and the temperature was raised to 80 ° C. The contents became a homogeneous molten state and were stirred, and then 59.1 g (0.3 mol) of 4-nitrophenol sodium salt dihydrate was gradually added while nitrogen gas was being bubbled through.
Next, raise the temperature slowly to 170-180 ℃ and keep the same temperature.
The reaction was carried out for 15 hours.

Immediately after completion of the reaction, the product was discharged into a porcelain container and cooled to obtain 100 g of a light tan solid product.

This was 4,4'-dinitrodiphenyl ether and had a purity of 97% excluding polyethylene glycol and inorganic salts by high performance liquid chromatography.

Recrystallization from ethanol gave a pure product of pale yellow prism crystals. The melting point was 144 to 145 ° C, and the results of elemental analysis were as follows.

Example 2 52 g (0.33 mol) of 4-chloronitrobenzene was added to a reactor equipped with a stirrer, a thermometer, a reflux condenser and a water separator.
Charge 41.7 g (0.3 mol) of nitrophenol, 15.6 g of polyethylene glycol (600) -diethyl ether (Nippon Special Chemical Industry Co., Ltd.) and 20 ml of benzene,
The mixture was heated with stirring while maintaining a reflux state while passing nitrogen gas through. Next, 35 g (0.31 mol) of 50% caustic potash solution
While distilling, water distilled off under the reflux condition of benzene was removed by water separation. After the completion of the dropping, after confirming that the water content was completely removed, the temperature was raised to distill off benzene. The temperature was kept at 160 to 175 ° C. and the reaction was carried out for 12 hours. Immediately after the completion of the reaction, the product was discharged into a porcelain container to obtain 96.5 g of a light tan solid product. This was 3,4'-dinitrodiphenyl ether and had a purity of 94.4% obtained by high performance liquid chromatography excluding catalysts and the like. The product recrystallized from ethanol had a melting point of 122 to 123 ° C.

Example 3 In the same reactor as in Example 1, 4-chloronitrobenzene 47.3
g (0.3 mol), 4-nitrophenol 13.9 g (0.1 mol), anhydrous potassium carbonate 16 g (0.115 mol) and polyethylene glycol 15 g with an average molecular weight of 600 are charged, and at a temperature of 165-170 ° C. while aeration with nitrogen gas. The mixture was reacted for 16 hours with stirring. After completion of the reaction, the discharged product was recrystallized from methanol to obtain 23 g of pale brown prism crystals of 4,4'-dinitrodiphenyl ether (yield 88.4%).

Claims (1)

[Claims] 1. A process for producing dinitrodiphenyl ethers, which comprises subjecting 4-chloronitrobenzene and nitrophenols to condensation reaction in the presence of a dehydrochlorination agent using polyethylene glycol or a lower alkyl ether thereof as a catalyst.