JPH0764770B2 - Method for purifying m-phenoxybenzyl alcohol - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for purifying m-phenoxybenzyl alcohol.

More specifically, it relates to a purification method for obtaining high-purity m-phenoxybenzyl alcohol with high yield.

In recent years, the demand for the safety of pesticides has become stronger and stronger, and there are great expectations for the low toxicity of pyrethroid pesticides. It has important significance in the development of pesticides.

(Prior Art) Conventionally, as a method for producing m-phenoxybenzyl alcohol, a method of chlorinating or oxidizing m-phenoxytoluene as a raw material is generally known.
It has not been satisfactory as an industrially inexpensive and advantageous method having the following drawbacks.

(1) A method by side-chain chlorination of m-phenoxytoluene.

In the chlorination reaction of the side chain methyl group, a second chlorine addition occurs at the benzyl position to generate a by-product, which requires lowering of selectivity and separation / purification, and hydrolysis in the next step is also complicated. .

(2) Method by oxidation of side chain of m-phenoxytoluene.

Oxidation of the side chain methyl group does not stop at the benzyl position with an alcohol but is oxidized to an aldehyde or a carboxylic acid.
The generated benzaldehyde or benzoic acid must be further reduced to lead to the desired product, and a large amount of potassium permanganate must be used during oxidation, which is complicated as in (1).

(3) Also, condensation of phenolate with m-chlorobenzoic acid ester or nitrile is known (French Patent No. 2456727), but the m-chlorobenzoic acid ester or nitrile used in this method is expensive, It cannot be an industrially advantageous method.

(4) Further, a method of obtaining m-phenoxybenzyl alcohol from m-hydroxybenzyl alcohol and prombenzene using copper powder as a catalyst is proposed (Japanese Patent Laid-Open No. 61434/48).
However, although the yield is low and brombenzene is an expensive raw material compared to chlorobenzene, a yield of about 80% is insufficient as an industrial production method.

The present inventors have previously found that m-hydroxybenzyl alcohol can be produced at a relatively lower cost than m-hydroxybenzoic acid. Therefore, this is used as a starting material and reacted with halobenzene to prepare a method for producing m-phenoxybenzyl alcohol. After intensive studies, a method for obtaining this in a high yield was also previously proposed (JP-A-61-186339). However, even with this method, it was not possible to obtain a satisfactory yield when using chlorobenzene at a low cost.

(Problems to be Solved by the Invention) The inventors of the present invention conducted further investigations to react m-phenoxybenzyl alcohol with a reaction of chlorobenzene and m-hydroxybenzyl alcohol in the presence of an inorganic base and a copper compound catalyst in a polar solvent. In the method of producing (1), it was previously proposed to obtain a highly pure m-phenoxybenzyl alcohol by conducting a condensation reaction in a specific temperature range and extracting the produced water out of the system (Japanese Patent Application No. 61-183494).

However, in the case of purifying and isolating m-phenoxybenzyl alcohol from the reaction product by this method as well, generally, chlorobenzene and a polar solvent are removed by a distillation operation from a filtration and washing solution obtained by filtration and washing. According to this general method, the filterability is significantly reduced due to the tar-like substance under normal filtration conditions, and the m-phenoxybenzyl alcohol during the distillation is further reduced. It has a drawback that the loss due to decomposition is large and cannot be ignored as an industrial purification method.

An object of the present invention is to provide an industrially advantageous m-phenoxy compound capable of smoothly performing a filtration operation, which is difficult by the conventional method, in a simple manner, and capable of significantly improving the distillation yield of m-phenoxybenzyl alcohol. It is to provide a method for purifying benzyl alcohol.

(Means for Solving Problems) The inventors of the present invention have conducted extensive studies to solve the above-mentioned problems, and as a result, filtered the reaction product at a high temperature and obtained a coarse m-
It was found that high-purity m-phenoxybenzyl alcohol with high yield can be obtained by adjusting phenoxybenzyl alcohol to a specific pH and performing distillation, and completed the present invention.

That is, according to the present invention, the reaction product obtained by the reaction of chlorobenzene and m-hydroxybenzyl alcohol in the presence of a copper compound catalyst and a base in a polar solvent is used to separate impurities contained therein by filtration at a high temperature. The chlorobenzene and the polar solvent are recovered from the obtained filtrate, and then washed with water or neutralized with an acid, and the pH is adjusted to 7 to 11 for distillation. Purification of m-phenoxybenzyl alcohol. Is the way.

Hereinafter, the present invention will be described in detail.

The raw materials used in the method of the present invention are chlorobenzene and m-hydroxybenzyl alcohol.

Further, the copper compound catalyst used is copper powder, copper halide, copper carbonate, or the like, or includes a substance which forms these copper as a complex.

These catalysts may be used alone or as a mixture. In particular, 8-oxyquinoline copper complex is a preferred catalyst.

The amount of these catalysts used is in the range of 0.5 to 5.0 mol% based on m-hydroxybenzyl alcohol.

Examples of the base used in the method of the present invention include sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate and the corresponding bicarbonates, and these may be used alone or in combination of two or more.

The amount of these bases used is 1.0 gram equivalent or more, preferably 1.0 to 2.0, based on m-hydroxybenzyl alcohol.
It is a gram equivalent.

The polar solvent that can be used in the present invention can be used if it is inert to the reaction, preferably N, N′-dimethylimidazolidinone, N, N′-dimethylformamide,
Dimethyl sulfoxide, N-methyl-2-pyrrolidone,
Examples include sulfolane, tetrahydrofuran, 1,4-dioxane and the like.

The amount used is not particularly limited, but in order to exert the solvent effect, it is necessary to be equivalent or more with respect to m-hydroxybenzyl alcohol. If the amount is too large, the volumetric efficiency of the reaction is lowered. Therefore, it is preferable to use it in the range of 1 to 10 times by weight in accordance with the amount of chlorobenzene used. The polar solvent is
You may use 1 type or in mixture of 2 or more types.

The reaction product usually contains a basic substance such as potassium carbonate and a copper compound such as cuprous chloride and an 8-oxyquinoline complex as impurities, and these impurities are m-phenoxybenzyl alcohol. It needs to be separated to increase the loss during purification.

As a separation method, a method of filtering and separating the solid matter in the reaction product is adopted. The temperature during this filtration is 70 ° C.
As described above, preferably 90 ° C. or higher to usually 110 ° C., and filtration at this temperature dramatically improves the filterability. If the temperature is lower than 70 ° C, the filtration time becomes extremely long or the filtration becomes impossible at all. Further, even if a filter aid is used, the filtration time cannot be shortened.

During filtration, it is usually desirable to perform filtration under a nitrogen atmosphere in order to prevent decomposition of m-phenoxybenzyl alcohol at high temperature.

The filtrate obtained by filtering under the above conditions recovers unreacted chromium benzene and polar solvent by distillation.

Thus, the crude m-phenoxybenzyl alcohol from which the impurities, unreacted substances, the solvent used and the like have been removed from the reaction product is purified by distillation.

According to a detailed study by the present inventors, it was found that the purification effect varies depending on the distillation conditions.

That is, the result of the examination was as follows. Figure-1
Are (1) purified m-phenoxybenzyl alcohol obtained by purification, (2) crude m-phenoxybenzyl alcohol obtained by filtering the reaction product solution to collect chlorobenzene and a polar solvent, (3) (2) Crude m-phenoxybenzyl alcohol obtained by washing the alcohol obtained in (4) with water, (4)
The crude m-phenoxybenzyl alcohol obtained by neutralizing the alcohol obtained in (2) with an acid was allowed to stand under a nitrogen atmosphere at 210 to 220 ° C. for deterioration test.
-It shows the relationship between the residual rate of phenoxybenzyl alcohol and time.

In the crude m-phenoxybenzyl alcohol of (2), the loss of m-phenoxybenzyl alcohol increases with time, but in the crude m-phenoxybenzyl alcohol washed with water or the crude m-phenoxybenzyl alcohol neutralized with an acid, the loss is almost lost. But rather less loss than pure m-phenoxybenzyl alcohol.

When zinc powder or sodium sulfite is used as a stabilizer and the same test as above is performed, the rough m
-Phenoxybenzyl alcohol becomes agar.

Thus, at high temperatures, the use of additives cannot prevent the loss of m-phenoxybenzyl alcohol.

As is clear from the above, in order to prevent the decomposition of m-phenoxybenzyl alcohol at high temperature, washing with water or neutralization treatment with an acid is necessary, and the crude m-phenoxybenzyl alcohol such as a polar solvent is mainly collected. The filtrate as a component needs to be washed with water or neutralized with an acid.

Therefore, in the method of the present invention, the filtrate containing crude m-phenoxybenzyl alcohol as the main component is washed with water or neutralized to adjust the pH to 7 to 11, and then distilled.

Washing the filtrate with water is a general embodiment of crude m-
A method in which water is added to the phenoxybenzyl alcohol while stirring, and washing is performed can be mentioned.

The amount of water used is 1 to 10 times by weight, preferably 2 to 4 times by weight that of the crude m-phenoxybenzyl alcohol.

The temperature at the time of washing with water is 30 to 100 ° C, preferably 50 to 80 ° C, and after stirring for a predetermined time, the aqueous layer is separated.

The pH of the crude m-phenoxybenzyl alcohol thus washed with water is adjusted to the range of 7 to 11, preferably 8 to 10.

At this time, an acid may be used for pH adjustment. The acid used may be any inorganic acid, but usually hydrochloric acid or sulfuric acid is used.

In the neutralization of the filtrate with an acid, generally, while stirring a liquid containing m-hydroxybenzyl alcohol, acid or water containing an acid is added dropwise to adjust the pH to 7 to 11.

At this time, the same acid as described above can be used as the acid to be used.

The coarse m obtained by adjusting the pH to 7 to 11
-Phenoxybenzyl alcohol is purified by distillation in the usual way.

Further, it is preferable to carry out the operation in a nitrogen atmosphere during the distillation purification in order to prevent the loss of m-phenoxybenzyl alcohol due to oxidation.

(Operation and effect) In the presence of a copper compound catalyst and a base, a polar solvent is used to react chlorobenzene with m-hydroxybenzyl alcohol to give m-phenoxybenzyl alcohol in a high yield.
When obtaining with high purity, it is necessary to remove impurities that are basic substances or copper compounds from the reaction product in a short time,
By performing high-temperature filtration at a temperature of 70 ° C. or higher, filtration can be performed in a short time without any problem.

Further, when the filtrate after recovering chlorobenzene and the polar solvent is distilled to obtain pure m-phenoxybenzyl alcohol, it is washed with water or neutralized with an acid to obtain an appropriate pH, and the filtrate is distilled. Even if exposed to a high temperature of 200 ° C. or higher, the loss is extremely small, and the purified m-phenoxybenzyl alcohol can be obtained in a high yield.

INDUSTRIAL APPLICABILITY The present invention is extremely excellent as an industrial method for producing pure m-phenoxybenzyl alcohol.

(Example) Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples.

In the reactor, N, N'-dimethylimidazolidinone 59.4 kg,
Chlorbenzene 51.9kg, m-hydroxybenzyl alcohol 18.98kg (converted to 100% purity), potassium carbonate 15.9k
g, cuprous chloride 0.30 kg, and 8-oxyquinoline 0.46 k
14 g of a reaction product containing an inorganic insoluble matter obtained by reacting at 180 ° C. for 10 hours was filtered at a temperature of 90 ° C. and filtered with a pressure filter equipped with a filter cloth to obtain a filtrate 115.4. kg was obtained (filtration time 15 minutes).

Next, wash the cake with 21.1 kg of chlorobenzene and wash the cake.
23.2 kg and a wet cake of 18.55 kg were obtained. Chlorobenzene and N, N'-dimethylimidazolidinone were collected by a distillation method by combining the filtrate and the washing solution, and 32.9 kg of the crude m-phenoxybenzyl alcohol thus obtained and 80 kg of pure water were charged into a water washer.
After stirring and washing with water at 30 ° C. for 30 minutes, the mixture was allowed to stand and separated to obtain a water layer of 79.2 kg and an oil layer of 32.5 kg. The content of m-phenoxybenzyl alcohol in the oil layer was 81.6%, and the yield of m-phenoxybenzyl alcohol in terms of purity was 98.6%.

Next, the oil layer was charged into a distiller, and while gradually depressurizing from the tower top 150 torr, complete dehydration was performed, and further depressurized to 10 torr, and a 1.62 kg fraction with a head top temperature of 114 to 194 ° C was cut as the initial distillate. . Subsequently, 25.6 kg of a fraction having a column top temperature of 194 to 196 ° C. was taken as a main fraction, and GLC analysis showed that the purity of m-phenoxybenzyl alcohol was 98.7%, and the yield in terms of purity from crude m-phenoxybenzyl alcohol was 93.9%. there were.

Comparative Example N, N′-Dimethylimidazolidinone 32.3 kg, chlorobenzene 18.7 kg (converted to 100% purity), potassium carbonate 8.61 kg, cuprous chloride 0.17 kg, and 8-oxyquinoline 0.25 kg are charged to the reactor. , 69.2 kg of a reaction product containing an inorganic insoluble matter obtained by reacting at 180 ° C. for 10 hours with stirring, was heated at 60 ° C. and applied to a pressure type filter equipped with a filter cloth to obtain 52.7 kg of a filtrate.
Was obtained (filtration time 100 minutes).

Next, wash the cake with 11.4 kg of chromium benzene and wash 1
3.8 kg and 12.2 kg of wet cake were obtained.

Combine the filtrate and washing solution, and use chlorobenzene,
The crude m-phenoxybenzyl alcohol obtained by recovering N, N'-dimethylimidazolidinone was 16.5 kg.
Subsequently, the top of the tower was set to 4 torr, and the fraction of the top temperature of 183 ° C was 1.5 kg.
Was first cut, and 10.6 kg of a fraction having a column top temperature of 183 to 187 ° C. was taken as a main fraction, and GLC analysis showed that the purity of m-phenoxybenzyl alcohol was 95.1%, and the purity conversion yield from the crude m-phenoxybenzyl alcohol was Was 73.0%.

(Effect of the invention) As can be seen from the effects of the examples and comparative examples, if impurities in the reaction product obtained from chlorobenzene and m-hydroxybenzyl alcohol in a polar solvent are filtered at high temperature, the filtration can be performed in a short time. You can Also, if the filtrate is dechlorobenzene, depolarized solvent, m-phenoxybenzyl alcohol is washed with water or neutralized to make it an appropriate pH, and then distilled,
The target substance can be obtained with high purity and high yield.

[Brief description of drawings]

Figure 1 shows m under nitrogen atmosphere at 210-220 ° C.
FIG. 6 shows the relationship between the residual rate and time of phenoxybenzyl alcohol in each case. The symbols in the figure have the following meanings. ●: Crude m-phenoxybenzyl alcohol obtained by recovering chlorobenzene and polar solvent from the reaction product ○: Washed crude m-phenoxybenzyl alcohol △: Crude m-phenoxybenzyl alcohol neutralized with acid

Claims (2)

[Claims] 1. A reaction product obtained by the reaction of chlorobenzene and m-hydroxybenzyl alcohol in the presence of a copper compound catalyst and a base in a polar solvent, the impurities contained therein are separated by filtration at high temperature. A method for purifying m-phenoxybenzyl alcohol, which comprises recovering chlorobenzene and a polar solvent from the obtained filtrate, washing with water or neutralizing with an acid, adjusting PH to 7 to 11 and distilling. . 2. The method according to claim 1, wherein the filtration separation temperature is 70 ° C. or higher.