JPS61200947A - Production of dinitrodiphenyl ether compound - Google Patents

Abstract

PURPOSE:To obtain the titled compound in high yield and purity, economically at a low cost, by condensing 4-chloronitrobenzene with a nitrophenol compound in the absence of solvent and in the presence of a dehydrochlorination agent, using a polyethylene glycol as a catalyst. CONSTITUTION:The objective compound can be produced by the condensation reaction of 4-chloronitrobenzene with a nitrophenol compound using a catalyst consisting of a liquid or low-melting polyethylene glycol preferably having an average molecular weight of 400-1,000 or its lower alkyl ether, in the presence of a dehydrohalogenation agent such as KOH, at 100-240 deg.C in the stream of an inert gas such as N2. EFFECT:There occurs little coloring caused by the production of by-products. The labor and cost of recovery, etc., are unnecessary, and the volume-efficiency of the apparatus is high. The reaction proceeds gently at a low temperature compared with conventional solvent-less process. USE:Intermediate for diaminodiphenyl ether useful as a raw material of polyamide imide.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to an improved method for producing dinitrodiphenyl ethers. More specifically, the production of dinitrodiphenyl ethers is characterized by carrying out a condensation reaction of 4-chloronitrobenzene and nitrophenols in the presence of a dehydrochlorination agent in the absence of a solvent using polyethylene glycol and its lower alkyl ethers as catalysts. Regarding the method.

These dinitro diphenyl ethers are intermediates for diaminodiphenyl ethers, which are raw materials for polyamide, polyamideimide, and polyimide.

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

For example, as a method for condensation without a solvent, a,l-dinitrodiphenyl ether is produced in a yield of 85 cm by combining 4-fluoronitrobenzene and 4-nitrophenol potassium salt (M, J, Rari
ck et al., J.Am.chem.Soc., 551
290 (193! l)) Salle, “L from romonitrobenzene 2-ditrophenol potassium salt in 10% yield.
+ 2,4-dinitrodiphenyl ether has been produced (Benyo et al., Pharmaceutical Journal, 79273 (1959)).

As a method of condensation using a solvent, various dinitro diphenyl ethers are produced using aprotic polar solvents such as N,N-dimethylformamide and dimethyl sulfoxide.

For example, 4-chloronitrobenzene and 3-ditrophenol potassium salt were condensed in N,N-dimethylformamide solvent to produce 3,4'-dinitrodiphenyl ether in 73% yield (J, , T.

Randall et al., J.Org.Chem.
274098-4101 (1962)).

(Problems to be Solved by the Invention) However, among these methods, methods performed without a solvent generally require the use of nitrobenzene substituted with a halogen such as fluorine or bromine, which has high reaction activity but is expensive. However, the reaction is extremely difficult with inexpensive chlorine-substituted nitrobenzene due to its low activity (M, J, R
arick et al., T. Am.

Chem, 80C, 551289 (1933)).

However, using these chlorine-substituted nitrobenzenes
As an example of a 1 mann reaction, 4-chloronitrobenzene and 4-ditrophenol (C) 4. / -Dinitrodiphenyl ether 75f 2-Chloronitrobenzene and 2-nitrophenol color 2,2'-Dinitrodiphenyl ether have been produced (Fukuni et al.

Pharmaceutical Journal, No. 1079-1080).

In these production examples, the reaction temperature was extremely high at 230 to 240°C, and there was no description of the yield, so the details are unknown, but as mentioned by M. J. Rarick et al. mentioned above, the reaction was extremely difficult. Therefore, it is expected that the yield will be extremely low.

Furthermore, it is known that the method carried out without a solvent carries the risk of the reaction occurring rapidly. For this reason, even during laboratory production, it is necessary to carefully control the reaction temperature while maintaining it in stages. Therefore, this method has the serious drawback of not being suitable for mass production.

Further, since this method uses a copper-based compound such as copper powder as a catalyst, it is obvious that purification of the target product requires extremely complicated operations and other disadvantages.

On the other hand, methods using solvents use relatively expensive solvents that must be recovered.

In addition, although this method generally has relatively good reaction selectivity, in addition to high molecular weight substances, azoxy compounds, which are difficult to separate from the target product, are produced as by-products.

Furthermore, when using a solvent such as dimethyl sulfoxide, if even a trace amount of these solvents remains in the target product, it may poison and deteriorate the noble metal catalyst used to produce diaminodiphenyl ethers by catalytic reduction of the target product. It is known that it will disappear.

Therefore, this method has drawbacks such as requiring a large amount of expense and labor for recovering the solvent and purifying the target product.

(Means for Solving the Problems) The present inventors have intensively studied methods that are inexpensive and can be produced industrially without these drawbacks. the result,
The present invention was completed based on the discovery that the condensation reaction of 4-chloronitrobenzene and nitrophenols can be carried out without a solvent when polyethylene glycols are used as a catalyst.

That is, the present invention is a method for producing dinitrodiphenyl ethers, which comprises condensing 4-chloronitrobenzene and nitrophenols in the presence of a dehydrochlorination agent using polyethylene glycol and its lower alkyl ethers as a catalyst. be.

In the method of the invention, 3.4'-dinitrodiphenyl ether and 4. Easy nitrodiphenyl ether can be produced.

The raw materials include 4-chloronitrobenzene and nitrophenols such as 3-nitrophenol and 4-nitrophenol. The reaction between chloronitrobenzene and nitrophenols may be carried out in stoichiometric amounts or in excess.

In the case of polyethylene glycol as the catalyst used,
Any compound having an average molecular weight of 200 or more can be used, but for industrial use, an inexpensive liquid to low melting point compound with an average molecular weight of 400 to 1000 is preferable.

Lower alkyl ethers of polyethylene glycol generally have 4≦2 ethylene oxide units, and these include tetraethylene glycol dimethyl ether, tetraethylene glycol diethyl ether, octaethylene glycol dimethyl ether, polyethylene glycol dimethyl ether, polyethylene Mixtures such as glycol diethyl ether are also used.

There is no upper limit to the amount of these catalysts used as long as it is 1 wt% or more based on the total raw materials, but if economic efficiency is taken into account,
A range of 50 wt% is preferable.

Bases used in the process of the invention include alkali metal carbonates, hydrogen carbonates, hydroxides or alkoxides, in particular potassium carbonate, sodium carbonate, potassium hydrogen carbonate, potassium hydroxide, hydroxide. Examples include sodium, potassium isopropoxide, and sodium isopropoxide.

The amount of these bases to be used may be at least equivalent to the nitrophenol, and specifically, a range of 1 to 3 equivalents is sufficient.

The method of the present invention is carried out substantially without solvent, but in some cases a small amount of azeotropic dehydration solvent such as benzene, toluene, xylene, or chlorobenzene may be added to remove water in the system. good.

The reaction temperature is around or above the melting point of the target product. That is, in the range of 100 to 240°C,
Preferably it is in the range of 130 to 200°C.

In a general embodiment of the present invention, a base is added to a predetermined amount of chloronitrobenzene and a catalytic amount of polyethylene glycol, etc., and the reaction is allowed to proceed at a predetermined temperature while passing an inert gas such as nitrogen gas through the mixture. Alternatively, an alkali metal salt of nitrophenol may be obtained in advance and this may be reacted with chloronitrobenzene in the presence of a catalyst such as polyethylene glycol.

Progress of the reaction can be monitored by thin layer chromatography and high performance liquid chromatography.

After completion of the reaction, post-treatment is carried out depending on the purpose of use, but in most cases the desired product can be obtained selectively, so in many cases it is possible to meet the intended use if the product is discharged as is and pulverized. Furthermore, the quality can be improved by washing with water or recrystallizing with a solvent or the like, if necessary.

(Functions and Effects) According to the method of the present invention, dinitrodiphenyl ethers can be produced with high purity and high yield, and furthermore, the method is characterized in that there is little coloring due to the formation of by-products.

In addition, since no solvent is used, there is no need for labor and expense for recovery, etc., and the volumetric efficiency of the apparatus is extremely high. This method is suitable for industrial implementation because it can proceed slowly at a lower temperature than other methods.

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

Example 1 4-chloronitrobenzea 4731 (0.5 mol) and an average molecular weight of 100 were placed in a reactor equipped with a stirring device and a thermometer.
The temperature was raised to 80°C. Since the contents were in a homogeneous molten state, they were stirred and then nitrogen gas was passed through the mixture to dissolve 4-nitrophenol sodium salt dihydrate 59.19 (0,3
mol) was added gradually.

Next, the temperature was gradually increased to 170 to 180°C, and the reaction was carried out at the same temperature for 15 hours.

After the reaction was completed, the mixture was immediately discharged into a porcelain container and cooled to obtain 10Of of a light yellowish brown solid.

This is 4. The purity of l-dinitrodiphenyl ether, polyethylene glycol by high performance liquid chromatography, and purity excluding inorganic salts was 97%.

Recrystallization with ethanol yielded pure pale yellow prismatic crystals. The melting point was 144-145°C, and the results of elemental analysis were as follows.

Elemental analysis (C Engineering 2H8N205) CI (N Calculated value (4) 55.39 3.1 10.7
7 Example 2 4-chloronitrobenzene 52f (0.33 mol) was added to a reactor equipped with a stirrer, a thermometer, a reflux condenser and a water separator.
, 3-nitrophenol 41.75' (0.3 mol)
, polyethylene glycol (600)-diethyl ether (manufactured by Nippon Tokushu Kagaku Kogyo Co., Ltd.) 15.62 nd and benzene 2nd were charged, and while nitrogen gas was passed through the reactor, it was heated under stirring and maintained at a reflux state. Next, while 35 f (0.31 mol) of a 50 ts caustic potassium aqueous solution was added dropwise, the water distilled out under the reflux state of benzene was removed by water separation. After the dropwise addition was completed and it was confirmed that the water had completely disappeared, the temperature was raised to distill off the benzene. temperature 16
The temperature was kept at 0 to 175°C and the reaction was carried out for 12 hours. After the reaction is complete,
Immediately drain into a porcelain container and a pale yellowish brown solid substance will be collected.
6.59 was obtained. This was 3,4'-dinitrodiphenyl ether, and the purity was 94.4% after removing the ashes and catalyst by high performance liquid chromatography.

The melting point of recrystallized from ethanol is 122-123℃
Met.

Example 3 4-chloronitrobenzene 47 was added to the same reactor as Example 1.
．． 3f (0,3 mol), 4-nitrophenol 135
1 (0,1 mol), anhydrous potassium carbonate 16f (0,11
5, mol) and polyethylene glycol 152 having an average molecular weight of 600 were charged, and the reaction was carried out at a temperature of 165 to 170° C. for 16 hours with stirring while blowing nitrogen gas. After the reaction was completed, the discharged product was recrystallized with methanol to obtain light brown prismatic crystals 232 of 4,4'-dinitrodiphenyl ether (yield: 88.4%).

Claims (1)

[Claims] 1) A method for producing dinitro diphenyl ethers, which comprises carrying out a condensation reaction of 4-chloronitrobenzene and nitrophenols in the presence of a dehydrochlorination agent using polyethylene glycol or its lower alkyl ethers as a catalyst.