JPH0710790A - Method for separating and purifying phenols - Google Patents

Abstract

PURPOSE:To separate and purify only a required phenol from a mixture of phenol isomers in high purity, industrially and advantageously by adding a specific salt to a mixture of Phenolic compounds to deposite complex crystal. CONSTITUTION:An alkylammonium salt is added to a mixture of phenolic compounds and only a specific phenolic compound is deposited as complex crystal with the alkylammonium salt and separated. Any of a ketone, an ester, an ether and a nitrile is used as a solvent and is preferably mixed with 1-50% of an alcohol.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for efficiently extracting only a specific phenol compound of interest from a mixture of phenolic compounds such as a reaction mixture of a hydroxylation reaction of an aromatic compound.

[0002]

2. Description of the Related Art Phenols are industrially important products, but they are compounds which are relatively prone to isomers in production. For example, when a hydroxylation reaction of an aromatic compound is carried out, a plurality of phenols having different hydroxyl group substitution positions are usually produced. If there is a large difference in boiling points among these plural phenolic compounds, the mixture can be separated by distillation, but in general, the boiling points are often close, and separation by distillation is difficult. In addition, there are industrial wastewaters containing phenolic compounds in various places, but the phenolic compounds are very harmful to the environment and need to be completely removed. Conventionally, it takes a lot of time and money to remove such a phenolic compound from wastewater.

The inventors of the present invention have studied the phenomenon in which a specific molecule of one kind continuously forms an inter-molecular force with another specific molecule to form a host-guest complex. And utilizing the host-guest complex formation,
A method for separating and concentrating a target compound from an isomer mixture, which is difficult to separate and purify due to its very similar physical properties, is industrially highly efficient and has been disclosed in patents and the like. That is, the present inventors molecularly designed a host compound that forms a host-guest complex only with the phenol compound in order to separate the target phenol compound from a mixture of phenol isomers, and the phenol of various compounds was The ability to form complexes with the class was tested. As a result, they have found that a compound having two or more amide groups often forms a host-guest complex with phenols, and applied for a patent. Specifically, fumaric acid amides and oxalic acid amides are disclosed in JP-A-60-46999 and JP-A-60-113535, and benzenetricarboxylic acid amides and benzenetetracarboxylic acid amides are disclosed in JP-A-60-113554. HirakiAkira 60-26299 Patent phthalic acid amide in Japanese, 1,2-cyclohexanedicarboxylic acid amide, △ ⁴ - cyclohexene-1,2-dicarboxylic acid amide, phenyl malonic acid amide was disclosed pyridinecarboxamide. Among the above amide compounds, by using fumaric acid amide, by crystallizing the m-cresol-fumaric acid amide complex from a 50/50 mixture of m-cresol and p-cresol and decomposing the complex, High-purity m-cresol could be recovered.

[0004]

[Problems to be Solved by the Invention] As the above-mentioned host compound, amides have an excellent effect, but only because the host-guest complex forms a relatively strong bond,
There is a problem that the operation of recovering phenols, which is a guest compound, from the host-guest complex becomes complicated. The best method was to heat the host-guest complex under reduced pressure, distill and separate the phenol, and leave the host compound in the bottom of the kettle. However, needless to say, this method is troublesome in the processing of the residue. An object of the present invention is to solve the above drawbacks of the prior art and to provide a host compound which is easy to operate and excellent in economic efficiency.

[0005]

[Means for Solving the Problems] The present inventors have made many efforts to test a large number of compounds as a host compound in order to search for a compound having no defects such as amides. As a result, it was unexpectedly discovered that an alkylammonium salt forms a host-guest complex with phenols, and the present invention has been completed. That is, the present invention is characterized in that an alkylammonium salt is added to a mixture of phenolic compounds and only a specific phenolic compound is fractionated as complex crystals with an alkylammonium salt, a method for separating and purifying phenols. Is.

The alkylammonium salt of the present invention incorporates various phenols in a stoichiometric ratio to form a crystalline inclusion complex. This inclusion complex incorporates phenols by forming a hydrogen bond with a phenol bound to a counter ion (for example, a halogen ion such as Br ⁻ , Cl ⁻ ) in a crystal lattice of an alkylammonium salt. It is estimated that This inclusion complex has a property that it is easily decomposed by dissolving it in a solvent and washing it with water, and the alkylammonium salt is extracted into the aqueous layer.

The method of the present invention is generally performed as follows. A mixture of an alkyl ammonium salt and a phenol isomer is heated in a solvent to dissolve it, and the mixture is allowed to stand at room temperature to precipitate a host-guest complex, and the precipitated crystal is filtered out. The crystals are redissolved in a solvent that dissolves the alkyl ammonium salt and stirred with water.
Then, the solvent layer is separated and the solvent is distilled off, whereby phenols having a low isomer concentration are obtained as a residue.

The alkyl ammonium salt used in the present invention is a compound represented by the general formula 1 or 2.

[Chemical 1]

[Chemical 2] (Where R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ ,
R ⁷ , R ⁸ , R ⁹ , and R ¹⁰ represent a linear alkyl group having 1 to 25 carbon atoms, and may be the same or different. X, X ^'is chlorine, bromine, represents a halogen atom such as iodine, it may be the same or different. n represents the number of methylene groups and is 1 to 20. )

Typical alkyl ammonium salts of the present invention are listed below: trimethyl hexadecyl ammonium bromide, trimethyl hexadecyl ammonium chloride, tetrapropyl ammonium bromide, tetrapropyl ammonium chloride, trimethylhexyl ammonium bromide, trimethylhexyl chloride, trimethyl octadecyl bromide. , Trimethyloctadecyl chloride, hexamethylenebistributylammonium bromide, hexamethylenebistributylammonium chloride and the like. The host compound of the present invention is p-phenylphenol, 4,
4 ^'- dihydroxy biphenol, ^2,2' - dihydroxy biphenol, 2,6-dihydroxynaphthalene,
A host guest complex can be formed with a phenolic compound such as β-naphthol, o-cresol and p-cresol.

The solvent used in the method of the present invention needs to have a certain degree of polarity because it is necessary to dissolve the ammonium salt, but if the polarity is too high, the phenol and the solvent or the alkylammonium salt and the solvent will interact with each other. The action becomes large and the complex does not precipitate. The preferred solvent is
Ketones such as acetone and methyl ethyl ketone, esters such as ethyl acetate and ethyl propionate, ethers such as diethyl ether and dimethoxyethane, and nitriles such as acetonitrile. These solvents can be used alone or as a mixture. Further, when the solubility is poor only with these solvents, it is preferable to enhance the solubility by partially mixing a solvent having a larger polarity such as alcohol. Suitable alcohols are methyl alcohol, ethyl alcohol, n-propyl alcohol and the like. The ratio of alcohol to be mixed is preferably 1 in the solvent.
% To 50%, more preferably 5% to 30%.

The molar ratio of the guest compound (phenol) to the host compound (alkylammonium salt) is 1:
0.01 to 1: 100 is suitable, but a more preferable range is 1: 0.1 to 1:10. The dissolution temperature in the case of forming the host-guest complex is not particularly hindered by heating the solvent to the normal pressure boiling temperature, but it is also possible to increase the boiling temperature by increasing the boiling temperature under pressure. The temperature for crystal precipitation is room temperature, but there is no problem, but it is possible to lower the temperature below room temperature by using a refrigerant. In the case of crystals that do not easily precipitate, the precipitation time can be shortened by cooling. The precipitated crystal may be purified by a recrystallization operation. The time required for precipitation is not particularly limited,
Usually, it precipitates in the range of 30 minutes to 20 days. If it takes more than 3 days, it is not industrially preferable operation time,
It is desirable to study the precipitation conditions and shorten them.

Surprisingly, the host-guest complex obtained according to the invention can be redissolved in a solvent capable of dissolving the complex and washed by shaking the solution with water or stirring it with water. Not only can the complex be decomposed, but the ammonium salt can be transferred to the aqueous layer. Since phenols remain on the solvent side, by removing the solvent by distillation or the like, it is possible to recover a highly pure phenolic compound having a low content of isomers. As the redissolving solvent for decomposing the complex,
The solvent used for forming the complex can of course be used, but a solvent that is not freely mixed with water is preferable. As a redissolving solvent, diethyl ether,
Ethers such as dinormal propyl ether and diisopropyl ether, esters such as ethyl acetate, normal propyl acetate and ethyl propionate, and halogen solvents such as methylene chloride and chloroform are preferable.

[0013]

According to the method of the present invention, only a specific phenol compound can be isolated from a solution containing phenols. Therefore, it becomes possible to obtain only the required phenol compound with high purity from the phenol isomer mixture, which has been difficult to separate and purify conventionally. This is very useful industrially. Further, the method of the present invention is effective as a means for easily removing harmful phenol from a waste liquid containing phenols by forming a water-insoluble host-guest complex, and has a great advantage for environmental purification. .

[0014]

EXAMPLES Next, the present invention will be described with reference to Examples. Example 1 3.85 g (10.6 mmol) of C ₁₆ H ₃₃ NMe ₃ Br (hexadecyltrimethylammonium bromide) and 0.90 g (5.29 mm) of 4-hydroxybiphenyl.
ol) and 0.90 g of 2-hydroxybiphenyl (5.
29 g) is poured into a mixed solvent of 25 ml of acetone / 5 ml of methanol and heated to dissolve. When the solution was left at room temperature, crystals (mp 186 to 216 ° C.) were soon deposited. The crystals are filtered off, redissolved in ether and stirred with water, then the ether layer is separated. 0.48 g of crystals by distilling away ether from the ether solution
(Yield 54%) was obtained. When the crystals were analyzed for purity by gas chromatography, 4-hydroxybiphenyl 97.
It was a mixture of 5% and 2-hydroxybiphenyl 2.5%.

Example 2 (nC_FourH₉)₃N (CH₂)₆N (n-C_FourH₉)
₃Br₂(Hexamethylene (bistri n-butylammonium
Ni) dibromide) 0.80 g (1.33 mmo
l) and 4,4^'-Dihydroxybiphenyl 0.25
g (1.33 mmol) and 2,2'-dihydroxybif
Enol 0.25g, ethyl acetate 5ml / methanol
Dissolve by heating in 1 ml of mixed solvent. Chamber with lysate
Allow to stand at high temperature and collect the precipitated crystals (mp191-194 ° C)
Collect by filtration, redissolve in ethyl acetate and stir with water.
After that, the ethyl acetate layer is separated. Distill off ethyl acetate
Thus, 0.17 g of crystals (yield 75%) was obtained. This crystal
Purity analysis using a gas chromatograph showed 4,
Four^'-Dihydroxybiphenyl 99.3%, 2,2 ^'
-A mixture of 0.7% dihydroxybiphenyl,
It was

[0016] Example _{3 C 16 H 33 NMe 3 Cl} ( hexadecyltrimethylammonium chloride) 0.80g, 4,4 ^'- dihydroxy biphenol 0.47 g (2.52 mmol) and 2,2'-dihydroxy biphenyl 0. 47 g (2.
52 mmol), 5 ml of acetone / 1 ml of methanol
It was heated and dissolved in the mixed solvent of. Leave the solution at room temperature,
The precipitated crystals (mp 152-177 ° C) are filtered off. The obtained crystals are redissolved in ethyl acetate and washed with water, and then the ethyl acetate layer is separated. Ethyl acetate was distilled off from the ethyl acetate solution to give 0.18 g of crystals (yield 37
%)Obtained. Was purity analysis of this crystal by using a gas chromatography Tato graph, 4,4'-dihydroxy biphenyl of 1.8%, 2,2 ^'- dihydroxy biphenyl 98.
It was a 2% mixture.

Example 4 0.50 g (1.88 mmol) of (n-C ₃ H ₇ ) ₄ NBr (tetrapropylammonium bromide),
0.30 g (1.88) of 2,6-dihydroxynaphthalene
mmol) and 2,7-dihydroxynaphthalene 0.30
g (1.88 mmol) was heated and dissolved in a mixed solvent of 5 ml of acetone / 1 ml of methanol. The solution is left at room temperature and the precipitated crystals (mp 189-190 ° C) are filtered off. The obtained crystals were redissolved in ether and washed with water, and then the ether layer was separated. The ether was distilled off from the ether solution to obtain 0.15 g of crystals (yield 50%).
When the purity of the crystals was analyzed using a gas chromatograph, 2,6-dihydroxynaphthalene 73.5%, 2,
It was a mixture of 26.5% of 7-dihydroxynaphthalene.

Example 5 0.64 g of C ₁₈ H ₃₇ NMe ₃ Cl (octadecyltrimethylammonium chloride) and 0.
20 g (1.85 mmol) and p-cresol 0.20
g (1.85 mmol) was dissolved by heating in a mixed solvent of 5 ml of acetone / 1 ml of methanol. The solution is left at room temperature to precipitate crystals (mp 147-175 ° C).
The precipitated crystals are collected by filtration, redissolved in ether and washed with water, and then the ether layer is separated. The ether was distilled off from the ether solution and the residue was 0.15 g (yield 75%).
Obtained. When the purity of the residue was analyzed by gas chromatography, it was a mixture of m-cresol 34.7% and p-cresol 65.3%.

Example 6 1.0 g (3.96 mmol) of C ₈ H ₁₇ NMe ₃ Br (octyltrimethylammonium bromide), 0.43 g (3.98 mmol) of o-cresol and 0.43 g (3.98 mmol) of p-cresol. ) To 5 ml of acetone
Dissolve by heating. The solution is left at room temperature and the precipitated crystals are filtered off. The obtained crystals (mp 146 to 175 ° C.) were recrystallized once more, then redissolved in ether and washed with water. The ether layer was separated, and ether was distilled off from the ether solution to obtain 0.10 g of a residue (yield 23%). When the purity of the residue was analyzed by gas chromatography, it was a mixture of o-cresol 62.0% and p-cresol 38.0%.

Example 7 0.58 g (2.59 mmol) of C ₆ H ₁₃ NMe ₃ Br (hexyltrimethylammonium bromide) and α-
Naphthol 0.32 g (2.22 mmol) and β-naphthol 0.32 g (2.22 mmol) were added to acetone 5
Dissolve by heating in ml. The solution is allowed to stand at room temperature and the precipitated crystals (mp 87-107 ° C) are filtered off. The crystals were redissolved in ether and washed with water, then the ether layer was separated. The ether was distilled off from the ether solution to obtain 0.19 g of a residue (yield 60%). When the purity of the residue was analyzed by gas chromatography, it was a mixture of α-naphthol 38.3% and β-naphthol 61.7%.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical indication location C07C 39/16 (72) Inventor El Nassin Beni Bunkyo-cho, Matsuyama city, Ehime prefecture Ehime University Faculty of Engineering Department of Industrial Chemistry Within

Claims (6)

[Claims] 1. Separation of phenols, characterized in that an alkylammonium salt is added to a mixture of phenolic compounds and only specific phenolic compounds are precipitated as complex crystals with the alkylammonium salt and fractionated. Purification method. 2. The method for separating and purifying phenols according to claim 1, wherein at least one selected from the group consisting of ketones, esters, ethers and nitriles is used as a solvent. 3. The method for separating and purifying phenols according to claim 2, wherein alcohols are mixed with the solvent in the range of 1% to 50%. 4. An alkylammonium salt is added to a mixture of phenolic compounds, and only a specific phenolic compound is precipitated as complex crystals with an alkylammonium salt for fractionation and then redissolved in a redissolving solvent, The method for separating and purifying phenols according to claim 1, wherein the redissolved solvent is removed after washing the solution with water. 5. The method for separating and purifying phenols according to claim 4, wherein at least one selected from the group consisting of ethers, esters and halogenated hydrocarbons is used as a redissolving solvent. By 6. The method of claim 1, p-phenylphenol, 4,4 ^'- dihydroxy biphenol, 2,
2 ^'- dihydroxy biphenol, 2,6-dihydroxynaphthalene, beta-naphthol, the method for the separation and purification o- cresol or p- cresol.