JPH0710810B2 - Method for producing nitrophenol - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing nitrophenol. More specifically, it relates to a method for producing nitrophenol, which comprises cleaving allyl nitrophenyl ether with formic acid or a salt thereof in the presence of a catalytic amount of a palladium compound and a catalytic amount of a trivalent phosphine compound.

Nitrophenol is a very important compound as a raw material for pesticides, pharmaceuticals, dyes, and monomers for heat-resistant polymers.

(Prior Art) It is widely known that o- and p-nitrophenol can be industrially easily produced by nitration of phenol. On the other hand, with regard to the preparation of m- nitrophenol, hydrolyzing via a diazonium salt from (1) m- nitroaniline (Organic. Synthesis. Collective (Org.Synth.Coll.), Vol 1 .404 ( 19
41)), (2) A method of hydrolyzing this via an alkyl m-nitrophenyl ether (JP-A-59-157,05).
9), (3) A method of hydroxylating nitrobenzene with hydrogen peroxide (West German Published Patent No. 3.135.559, etc.) is only known.

However, regarding these conventional techniques, in the method (1), since a large amount of acid and water must be used, volume efficiency is very poor, and a large amount of waste acid must be treated. Since a large amount of hydrochloric acid or hydrobromic acid must be used in the method of (1), the acid causes corrosion of the reactor, and the acid used is diluted after the reaction and is difficult to reuse repeatedly. In addition, even if inexpensive hydrochloric acid is used, the reaction must be carried out under high temperature and pressure. Furthermore, the method (3) produces a mixture of positional isomers, the yield is extremely low, and there is a problem in safety.
There are various drawbacks such as the above, and it is necessary to eliminate these drawbacks in order to carry out industrially.

Although m-nitrophenol is a very important material using various fine chemicals as a raw material, a method for industrially and inexpensively producing it has never been known.

(Problems to be Solved by the Invention) An object of the present invention is to provide an industrial method for producing m-nitrophenol, which does not have the drawbacks of the above-mentioned prior art.

(Means for Solving Problems) The present inventors have made various studies and studies in order to achieve the above object.

Therefore, as a method of eliminating the drawbacks of the conventional technology, the idea of using allyl nitrophenyl ether as a raw material was adopted.
-Detergently studied the method for producing nitrophenol.

The cleavage reaction of allyl phenyl ether using formic acid or its salt in the presence of Pdcl ₂ or pd (CH ₃ COO) ₂ and triphenylphosphine is already known. For example, in the presence of a catalytic amount of pdcl ₂ or pd (CH ₃ COO) ₂ catalyst and triphenylphosphine, the reaction with allyl phenyl ether produces phenol and propylene (Angew. Chem.), 85 , 986
(1973)), it is also known that when this reaction is applied to various allyl phenyl ethers, 1-olefin and phenol are produced by using formic acid or an amine salt of formic acid. (Tetrahedron Letters
ron Lett.), 1979 , 613). On the other hand, Pd / C or pd (CH ₃ CO
The presence of O) ₂ and trivalent phosphine compound, is allowed to act the triethylamine salt of formic acid or formic acid to aromatic nitro compound is part of a nitro group is also known conventionally be reduced to an amine, in particular of formic acid The method using a triethylamine salt is one of the powerful methods for reducing an aromatic nitro compound to an aromatic amine (Journal of Organic Chemistry, 42 , 3491 (19).
77)).

Among such conventional techniques, a formic acid or a salt thereof is reacted with allyl nitrophenyl ether having a group such as a nitro group that is easily reduced in the molecule in the presence of a Pd catalyst and a trivalent phosphine compound to form a nitro group. Until now, no attempt has been made to produce nitrophenol by only performing a cleavage reaction without reducing.

Such an attempt of the present invention surprisingly reduces the nitro group by reacting allyl nittophenyl ether with formic acid or a salt thereof in the presence of a catalytic amount of a Pd catalyst and a catalytic amount of a trivalent phosphine compound. Notwithstanding, it was found that only the allyl group is selectively eliminated and the corresponding nitrophenol can be quantitatively produced, and the present invention has been completed.

That is, the present invention is a novel production of nitrophenol characterized by cleaving allyl nitrophenyl ether with formic acid or a salt thereof in the presence of a catalytic amount of a Pd catalyst and a catalytic amount of a trivalent phosphine compound. It is about the method.

The compounds produced by the method of the present invention are three isomers of nitrophenol, specifically o-nitrophenol, m-nitrophenol and p-nitrophenol. In particular, the method of the present invention is useful for the production of m-nitrophenol, which has hitherto been industrially difficult to produce.

The compounds used as raw materials in the method of the present invention are three isomers of allyl nitrophenyl ether, specifically, allyl o-nitrophenyl ether and allyl m-.
Nitrophenyl ether and allyl p-nitrophenyl ether. These compounds can be easily produced by a condensation reaction of corresponding isomers of dinitrobenzene, chloronitrobenzene or bromonitrobenzene with allyl alcohol (for example, JP-A-58-58).
180,461,59-25,353,59-44,343).

As the Pd catalyst, a zero-valent or divalent palladium compound is used.

As the zero-valent Pd catalyst, specifically, tetrakis (triphenylphosphine) palladium, bis (triphenylphosphine) palladium, tetramethylpalladium,
(Maleic anhydride) Bis (triphenylphosphine)
Palladium, etc. are mentioned.

Specific examples of the divalent Pd catalyst include palladium chloride, palladium acetate, bis (pentanedionato) palladium,
Examples thereof include bis (triphenylphosphine) palladium chloride and bis (benzonitrile) palladium chloride. The amount of such a catalyst used is not particularly limited, but usually 0.01 to 2 mol% of the number of moles of the raw material is sufficient.

Examples of the trivalent phosphine compound include triethylphosphine, triisopropylphosphine, trialkylphosphine such as tri-n-butylphosphine, tricycloalkylphosphine such as tricyclohexylphosphine, triphenylphosphine, and tritolylphosphine.
A triarylphosphine such as tri (p-chlorophenyl) phosphine, a triaralkylphosphine such as tribenzylphosphine, a phosphine bridged with a methylene chain such as 1.2-bis (diphenylphosphine) ethane, and the like are used.

The amount of these used is not particularly limited, but usually used
A molar amount of 3 to 20 times that of the Pd catalyst is sufficient. The purity of the formic acid used is not particularly limited, and a water-containing product may be used. Further, it is acceptable to use a salt of formic acid instead of formic acid.

As the salt of formic acid, specifically, lithium formate, sodium formate, alkali metal salts such as potassium formate, magnesium formate, alkaline earth metal salts such as calcium formate,
Primary alkylamine salts such as ammonium formate, formic acid methylamine salt and ethylamine salt, secondary alkylamine salts such as formic acid dimethylamine salt and diethylamine salt,
In addition to tertiary alkylamine salts such as triethylamine salts of formic acid, aromatic amine salts such as aniline salts and pyridine salts of formic acid are used.

The amount of formic acid and the salt of formic acid used is not particularly limited. Usually, 1 to 5 times mol, preferably 1 to 2 times mol, of the raw material is sufficient.

The reaction medium is not particularly limited as long as it is reactive to the reaction, and examples thereof include alcohols such as methanol, ethanol and isopropyl alcohol, glycols such as ethylene glycol and propylene glycol, ethers, gioxane and tetrahydrofuran. , Ethers such as methyl cellosolve, aliphatic hydrocarbons such as hexane and cyclohexane, aromatic hydrocarbons such as benzene, toluene and xylene, esters such as ethyl acetate and butyl acetate, dichloromethane, chloroform, carbon tetrachloride, 1,2-dichloroethane, 1,1,2-trichloroethane,
Halogenated hydrocarbons such as tetrachloroethane and N,
N-dimethylformamide, dimethyl sulfoxide, etc. can be used. When a reaction solvent that is immiscible with water is used and the reaction proceeds slowly, it can be accelerated by adding a commonly used phase transfer catalyst such as a quaternary ammonium salt or a quaternary phosphonium salt. The amount of the solvent used is not particularly limited as long as it is sufficient to suspend or completely dissolve the raw materials, but usually,
0.5 to 10 times the weight of the raw material is sufficient.

The reaction temperature is not particularly limited. Generally, it is performed in the range of 20 to 200 ° C. The reaction time is not particularly limited and is usually 30 minutes to 10 minutes.
It is a range of time. The reaction pressure is not particularly limited, and normal pressure is usually sufficient.

Although the embodiment of the reaction is not particularly limited, usually, the raw materials are added in a state in which the Pd catalyst and the trivalent phosphine compound are dissolved in a solvent, and then formic acid is appropriately added or formic acid at a predetermined temperature with stirring. The salt is added little by little to carry out the reaction.

The end point of the reaction can be determined by thin layer chromatography or liquid chromatography, or by stopping the generated gas.

After completion of the reaction, the reaction solution is passed through to remove the catalyst, the solvent is distilled off, and the residue is distilled under reduced pressure to obtain the desired nitrophenol in high purity almost quantitatively.

(Operation and Effect) According to the method of the present invention, nitrophenol can be produced with high purity and almost quantitatively under mild conditions by the cleavage reaction of allyl nitrophenyl ether. In particular, the method of the present invention provides an extremely excellent method capable of producing m-nitrophenol at low cost and in high yield without using complicated steps, which has been difficult to produce industrially in the past.

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

Example 1 35 mg (0.16 mmol) of palladium acetate and 380 mg (1.45 mmol) of triphenylphosphine were dissolved in 70 m of methyl cellosolve, and further 20 g (0.112) of allyl m-nitrophenyl ether.
mol) is added. Heated to 85 ° C, 86% formic acid 7.2g (0.13mo
l) at 85-95 ° C for about 1 hour. Stir at 100-110 ° C for an additional 4.5 hours. According to liquid chromatography, the yield of m-nitrophenol was 100%. Over
The oil obtained by washing with methyl cellosolve and then concentration under reduced pressure was distilled under reduced pressure to obtain m-nitrophenol as a pale yellow oil, which immediately crystallized. Yield 1
4.5 g (93% yield), bp.120-122 ° / 3mmHg, mp.95-96
C, yellow crystals.

Example 2 Palladium chloride 20 mg (0.11 mmol) and triphenylphosphine 293 mg (1.12 mmol) were dissolved in methyl cellosolve 50 ml, and allyl m-nitrophenyl ether 10 g (0.056mo).
l) and 3.09 g (0.0671 mol) of 86% formic acid are added. 90-100 ° C
Stir for about 1 hour. The same post-treatment as in Example 1 was performed to isolate m-nitrophenol. Yield 7.0g (Yield
90%), mp.95-96 ° C, yellow crystals.

Example 3 The same operation as in Example 2 was performed except that allyl o-nitrophenyl ether was used as a raw material. Yield 7.3g
(Yield 93%), bp.94-96 ° C / 20mmHg, mp.44-45 ° C.

Example 4 The same operation as in Example 2 was performed except that allyl p-nitrophenyl ether was used as a raw material. Yield 7.2g
(Yield 92%), mp. 112-114 ° C.

Examples 5 to 9 Allyl m-nitrophenyl ether was used as the raw material, palladium chloride was used as the pd catalyst in the same manner as in Example 2, and the results of the other reaction as shown in the table are shown in the table. The yield obtained by liquid chromatography analysis is shown.

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Claims (2)

[Claims] 1. A process for producing nitrophenol, which comprises cleaving allyl nitrophenyl ether with formic acid or a salt thereof in the presence of a catalytic amount of a palladium compound and a catalytic amount of a trivalent phosphine compound. 2. Allyl nitrophenyl ether is allyl m.
-The method according to claim 1, which is nitrophenyl ether.