JPS6217573B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for selectively producing monoalkylresorcinols.

Many techniques have been known for the alkylation of phenols such as resorcinol, but in the reaction of phenols with alkylating agents, the position on the benzene nucleus carbon of the phenol that can be substituted with alkyl is It is known that if a plurality of are present, as the reaction continues, alkyl substitution will proceed sequentially and a polyalkyl substituted product will be produced unless there is a special reason such as steric hindrance.
That is, when resorcinol is alkylated by the conventional technology, the product at the initial stage of the reaction is mainly monoalkylresorcinol, but as the reaction rate of resorcinol increases, dialkyl-substituted products and even tri-alkyl-substituted products are successively produced. Polyalkyl substituted products such as alkyl substituted products have increased, and it has been difficult to produce monoalkyl substituted products with high reaction rate and high selectivity.

For example, Chemical Abstracts Volume 28
On page 3722, it is stated that resorcinol and approximately the reaction equivalent of tertiary butyl alcohol are mixed with concentrated phosphoric acid (d=1.85~
1.87) As a result of reaction in the presence of a catalyst, unreacted resorcinol 15.4%, monobutylresorcinol
It has been reported that a mixture having a composition ratio of 56.9% dibutylresorcinol and 27.7% dibutylresorcinol can be obtained.

In this way, although in the conventional method only monoalkyl substituted products are produced, if the reaction rate of phenols is increased, many undesirable polyalkyl substituted products are produced as by-products, and such by-products can be discarded. It becomes necessary to remove and dispose of it as a property. However, such disposal results in a very large economic loss in terms of raw materials and operations. For this reason, it is possible to improve the selectivity of monoalkyl substituted products by keeping the reaction rate of raw material phenols low, or to improve the raw material phenols by dealkylation, disproportionation reaction, transalkylation reaction, etc. of polyalkyl substituted products. Conversion to alkylating agents, monoalkyl substituted products, etc. are being carried out. However, in these methods, the productivity decreases, and in addition to the main reaction equipment, various equipment for reaction, separation, recovery, etc. and associated services are naturally required, which is extremely disadvantageous economically. Therefore, it is industrially advantageous to selectively obtain a monoalkyl substituted product by a one-step reaction that has a high raw material conversion rate and substantially suppresses the formation of polyalkyl substituted products. It has extremely great value and significance as a manufacturing method.

In view of the above, the present inventors have conducted intensive studies to solve these problems and produce monoalkylresorcinol industrially advantageously, and as a result, have arrived at the present invention.

That is, the present invention is characterized in that resorcinol and an alkylating agent selected from tertiary butyl alcohol, isobutyl alcohol, and isobutylene are reacted in an inert solvent in the presence of phosphoric acid at an initial concentration of 50 to 65% by weight. This is a method for producing monoalkylresorcinol.

In the present invention, the concentration of phosphoric acid used as a catalyst is a very important requirement for achieving the purpose of the present invention, and the concentration range is 50 to 65% by weight, preferably 55 to 63% by weight at the start of the reaction. is required. If this concentration exceeds 65% by weight, the production of dialkyl substituted products increases rapidly, while if it is less than 50% by weight, although the amount of dialkyl substituted products produced is small, a practical reaction rate cannot be obtained. The amount of phosphoric acid used is usually 80% by weight or more, preferably 150% by weight or more based on resorcinol, and the upper limit is not particularly limited in terms of the reaction, but it is preferably 400% by weight or less from the viewpoint of post-reaction treatment and economics. .

Although this amount of phosphoric acid is extremely large from the concept of catalyst amount in ordinary chemical reactions, the present invention also shows that it is not consumed in a single reaction and can withstand repeated use. This is one of the characteristics of

In addition, when alcohol is used as an alkylating agent in the present invention, a dehydration reaction occurs, and the phosphoric acid concentration decreases slightly at the end of the reaction, but in this case, some of the recovered phosphoric acid may be removed as necessary. Alternatively, the concentration may be adjusted by adding concentrated phosphoric acid or concentrating without removing it, and the resulting material may be recycled and used.

The next important element in achieving the object of the present invention is the solvent. The solvent added must be chemically inert to the resorcinol, alkylating agent, catalyst and products in the reaction system. Also,
Resorcinol is poorly soluble in solvents, but
The alkylresorcinol needs to be easily soluble, and suitable solvents having such properties include aromatic hydrocarbons such as benzene, toluene, xylene, ethylbenzene, ethyltoluene, and cumene. The higher the amount of solvent used, the more the selectivity of monoalkylresorcinol is improved, but it does not have a significant effect, and the appropriate amount is preferably 1 to 10 times the weight of resorcinol, and more preferably 3 to 6 times the weight of resorcinol.

Next, the alkylating agent used in the present invention needs to be selected from tertiary butyl alcohol, isobutyl alcohol, or isobutylene. Isobutylene is a gas at normal temperature and pressure, but a mixed gas containing isobutylene can also be used. A gas fraction containing isobutylene, commonly referred to as the B--B fraction, obtained, for example, from naphtha cracking, is a suitable alkylating agent.
The amount of alkylating agent used is a relatively important factor, and is usually 1.0 to 1.35 times, preferably 1.1 to 1.30 times by mole, relative to resorcinol. When the amount is less than 1.0 mole, the amount of unreacted resorcinol increases, and on the other hand, as the excess increases,
Since the amount of dialkyl substituted product increases, it is practically preferable to limit the amount within the above range.

The reaction temperature is generally preferably 50 to 100°C, more preferably 60 to 80°C. If the temperature is too high, loss of alkylating agent may occur; if the temperature is too low, practical reaction rates cannot be obtained.

The time required for the reaction varies depending on the conditions described above, but is usually 3 to 6 hours. However, even if the time is extended more than necessary, the composition of the reaction solution will not be impaired, nor will it be significantly advantageous for the purpose of the present invention.

The method of the present invention can basically be carried out either batchwise or continuously, but industrially the batchwise method is advantageous for implementation on small to medium scales.

When carrying out the present invention, the alkylating agent may be charged to the reactor at the same time as resorcinol, the solvent, and the catalyst, but usually resorcinol,
It is appropriate to charge the solvent and catalyst, raise the temperature to a predetermined temperature while stirring, and then add the alkylating agent continuously or intermittently. Although any alkylating agent is easily absorbed and the reaction proceeds rapidly, it is necessary to remove exothermic components in order to maintain a constant reaction temperature. Incidentally, in order to prevent the alkylating agent from escaping out of the reaction system, it is desirable to provide a reflux cooling device or the like in the reaction apparatus.

After the reaction is completed, the reaction solution is usually cooled, allowed to stand, and separated into an organic layer and an aqueous layer (catalyst layer). Most of the monoalkyl resorcinol is contained in the organic layer, so it is mixed with a small amount of alkaline aqueous solution.
After neutralizing a trace amount of phosphoric acid, the solvent is separated and removed by a conventional method to obtain a crude product of monoalkylresorcinol as a brown viscous liquid.
If necessary, it can be further purified by distillation, extraction, recrystallization, etc. The aqueous layer is used repeatedly in the next reaction after extracting the monoalkylresorcinol contained therein or as it is after adjusting the concentration as required.

Thus, according to the method of the present invention, a monoalkylated product of resorcinol can be produced with high reaction rate and high selectivity through a relatively simple one-step reaction, and the production of monoalkyl resorcinol is industrially advantageous. It becomes possible.

The present invention will be explained in detail below using examples.

Example 1 Resorcinol 33 was added to a 500 ml four-necked flask equipped with a stirrer, reflux condenser, thermometer and dropping bottle.
g, 120 g of toluene and 140 g of 60% phosphoric acid were heated in a hot water bath while stirring to raise the temperature to 70°C.
held.

Next, 27 g of tertiary butyl alcohol was added dropwise over 1 hour, and the reaction was continued by stirring at the same temperature for 5 hours. After the reaction was completed, the mixture was cooled to room temperature, transferred to a separator, and separated into an organic layer and a catalyst layer. After the catalyst layer was extracted three times with 50 g of ethyl ether, the ether layer was combined with the organic layer and neutralized with a saturated aqueous sodium carbonate solution. When this organic layer was analyzed by gas chromatography, the composition of the phenolic substances was 2.7% (0.9 g) of resorcinol, 95.1% (47.4 g) of monobutylresorcinol, and 2.2% (1.5 g) of dibutylresorcinol. The rate was 97.3%, and the selectivity to monobutylresorcinol was 97.7%.

Example 2 Resorcinol 33 was added to a 500 ml four-necked flask equipped with a stirrer, reflux condenser, thermometer and gas inlet tube.
g, 150 g of toluene, and 150 g of 60% phosphoric acid were charged, heated and maintained at 60°C. Then, while stirring, isobutylene gas was blown into the bottom of the flask through a gas blowing tube at a rate of 0.34 g (approximately 150 ml) per minute to absorb it for 1 hour, and then the reaction was carried out at 60° C. for 4 hours. After cooling to room temperature, Example 1
When the composition of the organic layer was analyzed by performing the same treatment as above, it was found to be 3.0% (1.0 g) of resorcinol, 94.6% (47.2 g) of monobutylresorcinol, and 2.4% (1.6 g) of dibutylresorcinol, and the reaction rate of resorcinol was 97.0. %, and the selectivity to monobutylresorcinol was 97.5%.

Example 3 Resorcinol was added to the same equipment used in Example 1.
33 g, 180 g of 50% phosphoric acid, and 200 g of xylene were charged, heated while stirring, and maintained at 80°C. Then, 27 g of isobutyl alcohol was added dropwise over 1 hour, and the mixture was maintained at the same temperature for 6 hours to react.
After the reaction was completed, the reaction solution was cooled to room temperature and treated in the same manner as in Example 1. The composition of the organic layer was analyzed and found to be 9.4% (3.1 g) of resorcinol, 88.9% (44.4 g) of monobutylresorcinol, and dibutylresorcinol. The reaction rate of resorcinol was 90.6%, and the selectivity to monobutylresorcinol was 98.1%.

Comparative Example 1 In the same apparatus as used in Example 1, 33 g of resorcinol, 120 g of toluene, and 130 g of 70% phosphoric acid were charged, and heated and maintained at 60° C. while stirring. Then, 27 g of tertiary butyl alcohol was added dropwise over 1 hour, and the reaction was then maintained at the same temperature for 3 hours. After the reaction was completed, it was cooled to room temperature, and the same post-treatment as in Example 1 was performed.The composition was analyzed and found to be 2.5% (0.8g) of resorcinol, 79.4% (39.6g) of monobutylresorcinol, and 18.1% (12.1%) of dibutylresorcinol. g), the reaction rate of resorcinol was 97.5%, and the selectivity to monobutylresorcinol was 81.4%.

Comparative Example 2 Into the same apparatus as used in Example 1, 33 g of resorcinol and 140 g of 60% phosphoric acid were charged, and heated and maintained at 70° C. while stirring.

Next, 29 g of tertiary butyl alcohol was added dropwise over 1 hour, and the mixture was maintained at the same temperature for 4 hours to react. After the reaction is complete, cool the reaction solution to room temperature and dilute it to 100%
The ether layers were combined and neutralized with saturated aqueous sodium carbonate solution. Analysis of this ether layer revealed that its composition was 6.5% (2.1 g) of resorcinol, 68.3% (34.1 g) of monobutylresorcinol, 24.2% (16.1 g) of dibutylresorcinol, 1.0% of tributylresorcinol and tar-like high boilers. The reaction rate of resorcinol was 93.5%, and the selectivity to monobutylresorcinol was 73.0%.

Claims (1)

[Claims] 1. Reacting resorcinol with an alkylating agent selected from tertiary butyl alcohol, isobutyl alcohol, and isobutylene in the presence of phosphoric acid at an initial concentration of 50 to 65% by weight in an inert solvent. A method for producing monoalkylresorcinol, characterized by: 2. The method for producing monoalkylresorcinol according to claim 1, wherein the inert solvent is an aromatic hydrocarbon. 3. The method for producing monoalkylresorcinol according to claim 2, wherein the aromatic hydrocarbon is one or more selected from benzene, toluene, xylene, ethylbenzene, ethyltoluene, and cumene.