JPS62164639A - Separation of phenols from catechols - Google Patents

Abstract

PURPOSE:A specific amount of alkali is added to a mixture of phenols and catechols, and they are separately obtained from the aqueous phase and the organic phase, respectively, utilizing the change in the distribution ratio of these phenols and catechols to water and organic solvents. CONSTITUTION:In the separation of a mixture of phenols and catechols, a basic alkali metal compound such as sodium hydroxide is added to the mixture in an amount of over the total molar amount of the phenols and catechols, preferably 4-40 times the total weight of the catechols and phenols in the form of an aqueous solution and the mixture is treated with an organic solvent immiscible with water such as toluene. The mixture separates into the aqueous phase and the organic phase and the catechols are mainly obtained from the aqueous phase, while the phenols are mainly collected from the organic phase. The extraction operation is preferably carried out at 10-90 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for efficiently separating phenols and catechols from a mixture containing them.

[Conventional technology]

In various organic synthesis reactions, both phenols and catechols can be obtained as a mixture, but since phenols and tocatechols generally have similar physical properties, it is difficult to efficiently separate them. If the target compound is thermally stable, it can be separated by distillation using the boiling point difference, but if it is thermally unstable and cannot be distilled or the boiling point difference is small, usually A method of separating by extraction operation is adopted.

As a reaction in which a mixture of catechols and 7-enols is produced, for example, a method for synthesizing benzo-7-ranol, which is an intermediate of carbofuran useful as a pesticide, has been reported by the following reaction route. (Tokkai Sho!; g-/711.3
3? ) That is, in this method, since the conversion rate of the reaction of hydrolyzing the phenols of the general formula CI) to produce the catechols of the general formula (1) is low, the resulting reaction mixture contains polyphonic unreacted phenols. This results in the inclusion of

Therefore, it is necessary to separate the 7 enols from the catechols in the reaction mixture and reuse the phenols in the hydrolysis reaction.

Generally, the method of separating the 7 enols tocatechols by solvent extraction is inefficient, and even in the above-mentioned benzofuranol synthesis method, it has been difficult to separate phenols and catechols well.

Regarding this separation method, we previously proposed a method in which extraction is performed using 1 mol or more of boric acid and alkali per 1 mol of catechols.

(Japanese Patent Application No. Sho J-9-/90 Da 01.) However, this method requires at least an equimolar amount of boric acid to the catechols, which has the disadvantage of increasing the separation cost.

[Problem that the invention seeks to solve]

The object of the present invention is to provide a method for separating phenols and catechols in a simple and economical manner.

[Failure to solve the problem]

The gist of the present invention is to stir a mixture containing phenols and tocatechols in a mixed solvent of water and a water-insoluble organic solvent containing a basic alkali metal compound in an amount (mol) greater than the sum of the moles of both. Phenols, characterized in that the organic phase containing mainly phenols and the aqueous phase containing mainly catechols are recovered by treating and then separating the phenols into an aqueous phase and an organic phase. and the method for separating catechols.

The present invention will be explained in detail below.

The mixture containing phenols and catechols that is the target of the separation method in the present invention may be of any kind; for example, it may be a mixture containing a large amount of both phenols and catechols, or a mixture containing only a trace amount of one of the components. It may also be a mixture containing it as an impurity.

Phenols and catechols are not particularly limited, and include phenol and catechol,
Generally speaking, phenols and catechols represented by the following general formula are mentioned (where Rt and & may be the same or different, and each hydrogen represents an atom, an alkyl group, an alkenyl group, an aralkyl group, etc., Y and X may be the same or different, and represent a hydrogen atom, halogen atom, nitro group, alkoxy group, etc.). In particular, according to the present invention, the above [1] and []
) The separation of the mixture is performed well.

Suitable basic alkali metal compounds used in the present invention include, for example, hydroxides such as sodium hydroxide and potassium hydroxide, and carbonates such as sodium carbonate and potassium carbonate. These alkaline substances are usually made into an aqueous solution, mixed with a water-insoluble organic solvent, and brought into contact with a mixture of phenols and catechols.

The amount of water used is usually 9 to IQ times the weight of the total amount of phenols and catechols, and water must be able to sufficiently dissolve at least the alkaline substances.

Examples of the water-insoluble organic solvent (under 9, abbreviated as organic solvent) used in the present invention include aromatic hydrocarbons such as toluene, benzene, xylene, and punidocumene, chlorobenzene, dichlorobenzene, trichlorobenzene, etc. halogenated aromatic hydrocarbons, aliphatic hydrocarbons such as hexane, heptane, octane, halogenated aliphatic hydrocarbons such as carbon tetranomide, ethylene dichloride, ethers, esters, nitriles, etc. are mentioned,
Among these, aromatic hydrocarbons are preferred. The amount of this organic solvent is usually 0.0 to 0 times the weight of water.

The amount of alkaline compounds affects the accuracy and efficiency of the separation of phenols and catechols. That is, as the amount of alkali increases, the accuracy of phase separation improves, but the amount of phenols extracted into the organic medium layer is small, so it is necessary to increase the number of treatments (extractions).

On the other hand, if the amount of alkali is small, the separation accuracy will deteriorate, but the number of extractions may be small. Therefore, the amount of alkali IJ is greater than or equal to the sum of the moles of phenols and catechols, preferably S-λ, S times the moles.

When carrying out the method of the present invention, if the target mixture of phenols and catechols is already present as an alkaline water bath solution, the dialkali and the phenols and catechols are usually selected by neutralizing the mixture with, for example, hydrochloric acid. Determine the number of moles of the alkali salts of the following types, adjust the amount of alkali in the aqueous solution to a specified amount from this value by adding acid or alkali, and then mix with an organic solvent and perform an extraction process to remove the phenols in the aqueous phase. Preferentially extracted into the organic phase.

In addition, when the mixture of phenols and catechols is an organic solvent solution, the sum of the moles of the phenols and catechols is usually determined, and an alkaline aqueous solution containing a specified amount of cereal potash is prepared according to this value. This is then mixed with the organic solvent solution and subjected to extraction treatment to extract catechols in the organic phase into the aqueous phase.

The extraction treatment at this time is usually 0 to 700°C, preferably 1°C.
It is carried out at temperatures of 0-90°C. Extraction is carried out very quickly by mixing. The extraction process may be carried out once, but depending on the type of phenol and catechol and the desired degree of separation, a multi-stage process of 1 to 0 stages is usually performed. If multiple stages are required, a mixing tank and a In addition to the combination of a mixing tank and a static tank, where the aqueous phase and the organic phase are brought into contact with each other in countercurrent or cocurrent flow, and extracted and separated at each stage, extraction is possible by combining countercurrents in a tower format. It is also possible to do so.

Various types of such column-type extraction separation columns are known, and although they are not particularly limited, RDO
(Rotary Disk Contactor) or a curl column are preferably used.

RDO has a cylindrical structure with a large number of compartments created by annular stator rings fixed at equal intervals on the tower wall, and a rotating disk for central stirring is installed in each compartment. This is a stirring type extraction tower.

On the other hand, the curl column is a pulsating extraction type in which many perforated plates are installed in a cylindrical column, and the perforated plates move up and down to give vertical vibrations to the liquid staying in the column.

In both cases, extraction is usually carried out by feeding a light liquid from the bottom of the column and a heavy liquid from the top of the column and bringing them into countercurrent contact within the column.

The separated aqueous phase and organic phase are treated as appropriate depending on the purpose. For example, in the case of isolating catechols from an aqueous phase, although it depends on the type of catechols, a mineral acid such as hydrochloric acid or sulfuric acid is usually added to the aqueous phase to adjust the pH of the mixture to 3 or less, preferably λ or less, and catechols can be recovered by separating the resulting oil phase. On the other hand, when isolating the 7 enols from the organic phase, the alkali 11 mixed in the organic phase is normally oxidized with mineral acid if necessary, and then the organic common medium and the phenols are separated by distillation. can do.

[For production]

By adding a specific amount of alkali to a mixture of phenols and catechols, the distribution ratio of phenols and catechols to water and organic solvent changes, with catechols being extracted into the aqueous phase and phenols being extracted into the organic solvent. It becomes easier.

[Actual example]

The present invention will be explained in more detail using actual examples, but the present invention is not limited to the following examples unless the gist of the present invention is exceeded.

Tortoise Example Koyleftenyl-6-chlorophenol (D/, 06
After adjusting the alkali concentration of various caustic soda aqueous solutions containing ~23 tqb, J-isobutenylcatechol [u'3, coj-J, J7t to Q, j mo1/9 (
Add hydrochloric acid if necessary),! FO order X/100H
Using a glass RDO with L and number of compartments S, continuous countercurrent extraction of phenol [1] was carried out by feeding benzene from the bottom of the column and an aqueous solution of caustic soda from the top of the column.

After operating the RDol under the conditions shown in Table 7, the RD
When the contents of catechol and phenol components contained in the aqueous phase and benzene phase discharged with O were determined, the results shown in Table 7 were obtained.

In addition, the aqueous phase was subsequently adjusted to pH- by adding hydrochloric acid, and the catechol component was recovered by separating it into an aqueous phase and an oil phase.
On the other hand, the benzene phase was distilled to recover diphenols.

〔Effect of the invention〕

This invention makes it possible to extract phenol and catechol, which are difficult to separate, such as imptenyl-6-chlorophenol and 3-imbutenylcatechol, with water and organic solvents through simple operations, making it economical and practical. This is a typical method.

Sender: Mitsubishi Chemical Industries, Ltd. Representative Patent Attorney Hase - (other/name)

Claims (2)

[Claims] (1) A mixture containing phenols and catechols is mixed with a mixed solvent consisting of water and a water-insoluble organic solvent containing a basic alkali metal compound in a molar amount greater than the total molar amount of phenols and catechols in the mixture. Phenols and catechols, characterized in that an organic phase mainly containing phenols and an aqueous phase mainly containing catechols are recovered by stirring the mixture in a phenol and then separating the aqueous phase and the organic phase. separation method. (2) Phenols and catechols have at least one substituent selected from alkyl groups, alkenyl groups, aralkyl groups, halogen atoms, nitro groups, and alkoxy groups on the benzene nucleus. A separation method according to claim 1, characterized in that: