JPS6042781B2 - Method for producing symmetrical diphenyl ethers - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the production of symmetrical diphenyl ethers represented by the general formula @1@Z5-nZ5-n.

(In the formula, Y represents a nitro group, at least one of which occupies the ortho or para position with respect to the ether bond.

Z represents hydrogen, an alkoxy group, or an alkyl group,
n represents 1 or 2. ) The compounds obtained according to the present invention are useful in the production of medicines, agricultural chemicals, synthetic resins, etc. Generally, this series of compounds is produced by the so-called Williamson reaction, in which a nuclear-substituted halogenated benzene is reacted with an alkali metal salt of a nuclear-substituted phenol. In this case, two types of raw materials are required: a nuclear-substituted halogenated benzene and the corresponding alkali metal salt of phenol.Moreover, if the sodium salt of phenol is used as a raw material, the reaction will hardly proceed and an expensive lithium salt is generally required. shall be. Japanese Patent Publication No. 44-1433 and German Patent No. 1290147 disclose a method for producing symmetrical diphenyl ethers using only nuclear-substituted halogenated benzene as a raw material, but in both cases, a polar aprotic solvent is used as the reaction solvent. Potassium carbonate or hydroxide is required and is expensive.

The present inventors have discovered that by using a phase transfer catalyst, sodium hydroxide can be used in the same way as potassium hydroxide when producing symmetrical diphenyl ether using only nuclear-substituted halogenated benzene or only nuclear-substituted nitrobenzene as a raw material. The present inventors have discovered that a nonpolar solvent such as benzene can be used as a reaction solvent and that the reaction can proceed without an organic solvent, leading to the method of the present invention.

That is, the present invention is based on the general formula (where Y, Z, and n are the same as above, X is a nitro group,
Indicates a chlorine, bromine, iodine, or fluorine atom.

) or a nuclear-substituted halogenated benzene is used as a raw material and reacted with an alkali metal hydroxide in the presence of a phase transfer catalyst (where Y, Z, and n are as described above).

) is a method for producing symmetrical diphenyl ethers represented by Examples of the nuclear-substituted nitrobenzene or the nuclear-substituted halogenated benzene that can be applied to the method of the present invention include ortho-dinitrobenzene, varanitrobenzene, 2●3-dinitrotoluene, 2●5-dinitrotoluene, 3●4-dinitrotoluene, 2◆3 -Nitrovaraxylene, 2●5-dinitromethaxylene, orthochloronitrobenzene,
Parachloronitrobenzene, 4-chloro3-nitrotoluene, 2-chloro5-nitrotoluene, 4-bromo3
-nitroanisole, 2-fluoro5-nitroanisole, 2,4-dinitrofluorobenzene, and the like.

Examples of the phase transfer catalyst used in the present invention include quaternary ammoniums having an alkyl group or an allyl group, such as tetra n-butylammonium chloride, benzyltriethylammonium bromide, tetra n-butylphosphonium chloride, and cetyltri n-butylphosphonium chloride. salts or quaternary phosphonium salts, or
Examples include amine oxides such as -butylamine oxide, and crown ethers such as 18-crown-6.

There is no particular limit to the amount of catalyst added, but usually the raw material nuclear-substituted nitrobenzene or nuclear-substituted halogenated benzene 1
The range is from 0.0005 mol to 0.05 mol.

The alkali metal hydroxides used in the method of the invention include sodium hydroxide, potassium hydroxide, and lithium hydroxide.

Furthermore, the concept also includes alkali metal salts of weak acids that produce alkali metal hydroxides by hydrolysis when made into aqueous solutions, such as sodium carbonate and sodium salts of phenol.Alkali metal hydroxides are solids. Although it can be added as is, it is usually added as an aqueous solution.

The amount of alkali metal hydroxide added is not particularly limited as long as it is 1 mol or more per 1 mol of nuclear-substituted nitrobenzene or nuclear-substituted halogenated benzene as the raw material, but it is usually between 1 mol and 5 mol.
It is in the range of 0 mol. When an alkali metal hydroxide is added as an aqueous solution, the catalytic effect will not be exhibited if the concentration is too dilute, so it is usually used at a concentration of 1% by volume or more. According to the method of the present invention, the desired symmetrical diphenyl ethers can be produced by simply heating a nuclear-substituted nitrobenzene or a nuclear-substituted halogenated benzene and an aqueous solution of an alkali metal hydroxide while stirring and mixing them in the presence of a phase transfer catalyst. However, the yield of symmetric diphenyl ethers can be increased by adding a nonpolar solvent that forms a two-layer system with water, so benzene,
React by adding aromatic hydrocarbons such as toluene and cymene, halogenated hydrocarbons such as dichloromethane, ethyl bromide, trichloroethylene, and chlorobenzene, or ethers such as ethyl ether, isopropyl ether, and phenylethyl ether. will be held.

In this case, since the reaction solution forms two liquid phases, an organic layer and an aqueous layer, the reaction is carried out under strong stirring in order to improve the contact between the phases and increase the reaction rate.

The reaction temperature is usually selected in the range of 50°C to 300°C, and the reaction time varies greatly depending on the reaction temperature, stirring intensity, etc., and is usually in the range of several tens of minutes to several days. The method of the present invention will now be further illustrated by examples.

Example 1 Orthodinitrobenzene 6.0g (0.0357mol)
, 40 ml of benzene, 60 ml of a 50 wt% aqueous solution of caustic soda, and 0.2 y of tetra n-butylammonium chloride as a phase transfer catalyst were charged into an autoclave with an internal volume of 300 ml, and after replacing the air in the autoclave with nitrogen, the mixture was heated at 100°C for 60 ml. Time, 1200r. p. The reaction is carried out under stirring for m.

After cooling, the contents of the autoclave are removed and extracted with benzene. The benzene extract is distilled under reduced pressure to remove the solvent. Next, 0.1y of unreacted raw material was recovered by steam distillation, and the residue was recrystallized from alcohol to obtain bis(
3.7y of 2-nitrophenyl)ether was obtained. (Yield 81.1%)M. pll4-115yC0 Example 2 The same procedure as in Example 1 was performed except that benzene was not added; 1.2f of the raw material was recovered to obtain 0.5y of bis(2-nitrophenyl) ether.

Example 3-5 In Example 3, tetra n was used as a phase transfer catalyst.
- The same procedure as in Example 1 except that in Example 4, 0.2y1 of butylammonium bromide and 0.2y1 of tri-n-butylamine oxide were used in Example 5, and 0.2y1 of 18-crown-6 was used in Example 5. The results shown in Table 1 were obtained.

C Examples 6 and 7 In Example 6, 6.0f of valachlornitrobenzene and 6.0y of 4-chloro3-nitrotoluene were used in place of orthodinitrobenzene in Example 7, and the reaction was carried out at 150°C. The same operations as in Example 1 were performed except for the points mentioned above, and the results shown in Table 2 were obtained.

Example 8 Valachlornitrobenzene 15.0y (0.0955 mol), sodium carbonate 27.8q (0.262 mol),
90 y of water and 0.6 y of tetra n-butylphosphonium bromide as a phase transfer catalyst were charged into an autoclave with an internal volume of 300 m1, and after replacing the air in the autoclave with nitrogen, the mixture was heated at 170°C for 6 hours with stirring at 1200 rpm. The reaction was carried out.

Claims (1)

[Claims] 1 General formula ▲ Numerical formula, chemical formula, table, etc. ▼ (In the formula, X represents a nitro group, chlorine, bromine, iodine, or fluorine atom. Y represents a nitro group, and at least one Z shall occupy the ortho or para position with respect to X. Z represents hydrogen, an alkoxy group, or an alkyl group. n represents 1 or 2.
) or a nuclear-substituted halogenated benzene is reacted with an alkali metal hydroxide in the presence of a phase transfer catalyst.
There are chemical formulas, tables, etc. ▼ Method for producing symmetrical diphenyl ethers represented by (in the formula, Y, Z, and n are as described above). 2. A patent for using as a phase transfer catalyst one selected from the group of compounds consisting of quaternary ammonium salts or quaternary phosphonium salts, amine oxides, and crown ethers having an alkyl group or allyl group, or a mixture thereof. The method of claim 1. 3. The method according to claim 1 or 2, wherein a nonpolar solvent that forms a two-layer system with water is present during the reaction.