JPS6056146B2 - Method for producing furfuryl alcohol - Google Patents

Description

Detailed Description of the Invention The present invention is based on the general formula (l) (I) (wherein R_1 represents a hydrogen atom or a methyl group, and R_
2 represents an allyl group or an α-methylallyl group).

The furfuryl alcohol represented by the general formula (I), which is the object of the present invention, is a useful intermediate for agricultural chemicals, medicines, fragrances, and the like.

Generally, as a method for producing an alcohol compound from a carbonyl compound by a Grignard reaction, a Grignard reagent is prepared in advance and the carbonyl compound is reacted with the Grignard reagent.

・In fact, the method of G. Piancatelli et al. (Tetrahe
dr0n, ri0134, 2775-2778 (1978
)), allyl bromide and magnesium are reacted in advance to obtain allyl magnesium bromide, which is then reacted with 5-methylfurfural and then hydrolyzed to obtain the desired product. However, since allyl halides have higher activity than other common halides, side reactions such as Wurtz-type reactions are likely to occur, making it difficult to obtain the Grignard reagent in good yield.

In addition, when using inexpensive allyl chloride as the allyl halide, J. OrgChem. , L, 359-37
2 (1944), allylmagnesium chloride is insoluble in ethyl ether and requires vigorous stirring, making it difficult to employ in industrial scale production. Alternatively, for example, J. Org. Chem. , figure 3269~
3272 (1963), a method in which a carbonyl compound and allyl chloride are simultaneously reacted in ethyl ether has also been studied, but when this method is applied using allyl chloride and 5-methylfurfural, Grignard The reaction product does not dissolve in ethyl ether and crystals precipitate, and the viscosity also increases, which has the disadvantage of being extremely disadvantageous industrially in terms of stirring efficiency, removal of reaction heat, and operability. There is.

Previously, the present inventors developed a method for producing 5-methyl-2-allylfurfuryl alcohol (Japanese Patent Application No. 55-47329) that solved the various drawbacks of the conventional method. As a result of further studies to minimize the complexity of dehydration operations when recovering and reusing the tetrahydrofuran used as a solvent in By using a mixed solvent of hydrocarbons, the general formula can be obtained in high yield and with industrial advantage. (1
) It was discovered that furfuryl alcohols represented by the following formula could be obtained, and the present invention was completed.

That is, the present invention involves reacting a furfural represented by the general formula (■) (in which R1 has the same meaning as above) with magnesium and allyl chloride or α-methylallyl chloride, and then hydrolyzing the mixture. When synthesizing the furfuryl alcohol represented by the general formula (1), a mixed solvent of tetrahydrofuran and an aromatic hydrocarbon is used as a reaction solvent, and magnesium is added to the mixed solvent containing the general formula (■ This is a method for producing furfuryl alcohols represented by the general formula (1), characterized in that the furfurals represented by formula (1) and allyl chloride or α-methylallyl chloride are reacted simultaneously.

The present invention will be explained in detail below.

In the present invention, the use of a mixed solvent of tetrahydrofuran and an aromatic hydrocarbon is a very important requirement for achieving the object of the present invention.

Tetrahydrofuran is considered to be the most suitable solvent because of its high solubility for Grignard reagents and Grignard reaction products, but when recovering and reusing it, it is quite difficult to dehydrate it, and it is difficult to carry out dehydration operations and dehydration equipment. It is desirable to reduce the amount of tetrahydrofuran used as much as possible. However, there is a limit to the reduction in the amount used due to an increase in the viscosity of the reaction solution. However, by using a mixed solvent of tetrahydrofuran and an aromatic hydrocarbon according to the method of the present invention, it has become possible to use the minimum amount of tetrahydrofuran to dissolve the Grignard reagent and Grignard reactant. . That is, the amount of tetrahydrofuran used in the present invention may be at least 0.5 times the weight of furfural as a raw material, and the amount of aromatic hydrocarbon mixed with this may vary slightly depending on the type, but in general The upper limit can be selected from 1 times by weight to an extent that does not interfere with the reaction.

Examples of aromatic hydrocarbons used here include benzene, toluene, and xylene. According to the method of the present invention, there is no concern about crystal precipitation of Grignard reaction products, and furthermore, it has become possible to significantly reduce the amount of tetrahydrofuran used.

As a result, it is not only possible to avoid the difficulties of 1) removal of reaction heat, 2) stirring, and 3) transportation of reaction products due to crystal precipitation, but also very advantageous in terms of recovery and reuse of the reaction solvent.

That is, since tetrahydrofuran has infinite solubility in water and has an azeotropic point with water, extractive distillation or the use of a suitable dehydrating agent is required to dehydrate and reuse it, but the method of the present invention According to, for example, tetrahydrofuran can be easily recovered from the aqueous layer by separating the reaction solution into an organic layer and an aqueous layer after the completion of the reaction, and water in the organic layer can be removed by azeotropic dehydration with toluene. .

Further, it is also a very important requirement for achieving the object of the present invention that the furfurals represented by the general formula (■) and allyl chloride or α-methylallyl chloride are allowed to act simultaneously.

Here, the furfurals and allyl chloride or α-methylallyl chloride can be used as a mixed solution, separately, or mixed with a mixed solvent of tetrahydrofuran and an aromatic hydrocarbon and allowed to act simultaneously.

In this way, by simultaneously reacting the furfurals represented by the general formula (■) with allyl chloride or α-methylallyl chloride, it is possible to obtain Grignard reaction products in high yields even at higher reaction temperatures. At the same time, as mentioned above, combined with the fact that crystals do not precipitate, the burden of heat removal can be significantly reduced, the reaction time can be greatly shortened, and even a slight excess of allyl chloride or α-methylallyl chloride and magnesium can be used. Production on an industrial scale becomes very advantageous.

Here, the simultaneous action as referred to in the present invention may be continuous or intermittent as long as one component does not extremely precede the other, and the action time and action speed are not particularly limited. However, it goes without saying that both cannot be added instantly.

In the method of the invention, the reaction temperature is preferably -20'C.
to 6CfC.

A reaction temperature that is too low is undesirable because it increases the viscosity of the reaction liquid and increases the burden of heat removal. Further, there is no particular restriction on the reaction pressure, and when the reaction is carried out under reduced pressure, it becomes possible to remove heat by reflux and control the temperature accordingly. In the method of the present invention, the molar ratio of each reaction raw material is based on that which is desired to be completely consumed, and the others may be in slight excess. carbonyl compound 1
Compared to the conventional method where 1.3 to 2.2 moles of allyl chloride or α-methylallyl chloride were used per mole, this is very advantageous in terms of reducing raw material costs. The raw material that you want to completely consume can be arbitrarily selected by considering various requirements such as the influence on the subsequent process and the reaction equipment. There is no need to remove or recover the reacted magnesium, which is advantageous from an industrial perspective.

In this Grignard reaction, before simultaneously reacting the furfurals represented by the general formula (■) with allyl chloride or α-methylallyl chloride, the mixture of tetrahydrofuran and aromatic hydrocarbon to which magnesium has been added is added. It is desirable to add a small amount of allyl chloride or α-methylallyl chloride and, if necessary, iodine to the reaction mixture in advance to start the reaction.

The Grignard reaction product thus obtained is then hydrolyzed to give the desired general formula (1).
The furfuryl alcohol shown is obtained. The conditions for this hydrolysis are not particularly limited, and the hydrolysis can be easily carried out by a conventional method using an aqueous solution of ammonium chloride, hydrochloric acid, sulfuric acid, etc., or a mixture thereof, and the hydrolysis reaction product is can be purified by distillation etc. if necessary.

Thus, according to the method of the present invention, furfuryl alcohols represented by general formula (1) can be obtained in high yield and industrially very advantageously.

The present invention will be explained below using examples. Example 1 Magnesium shavings 13.5f were placed in a reaction vessel in a nitrogen stream.
I, Tetrahydrofuran (water concentration 300 ppm) 27
．． 5 g of toluene and 27.5 g of toluene were charged, and 2.8' of allyl chloride was added dropwise at room temperature while stirring, and the mixture was left for 5 minutes.

(The start of the reaction is confirmed by an exotherm). Next, a mixed solution consisting of 55.0f of 5-methylfurfural, 43.1f of allyl chloride, and 165.2f of toluene was added dropwise under stirring at a reaction temperature of 40°C over a period of 4 hours.
Holds time. After the reaction is completed, this reaction solution and 15.0WL
% sulfuric acid aqueous solution was poured into 211 f of water while stirring for 4 times to maintain the pH of 8 or higher, and then 30 f of Nofan% acetic acid aqueous solution was added dropwise to bring the pH to 5. The temperature was lowered to 100 ml and maintained at the same temperature for 1 hour. After the reaction was completed, the reaction solution was separated into an aqueous layer and an oil layer.

Extract the water layer with 150g of toluene, add the toluene layer to the previous oil layer, and add this oil layer to the oil layer. After pre-cleaning with a % aqueous sodium carbonate solution, the solvent was distilled off. Next, vacuum distillation (95-9TC/1
．． 33×1CPPa) and 2-(1-hydroxy-3-
74.6 fI of (butenyl)-5-methylfuran were obtained. 5
- The yield based on methylfurfural was 98.0%, and the yield based on magnesium was 88.2%. Example 2 Magnesium shavings 14.58 kg were placed in a reaction vessel in a nitrogen stream.
f, tetrahydrofuran (water concentration 300 ppm) 48
．． After 0f1 and 0.15g of iodine were charged, 3.26y of 3-chloro-1-butene was added dropwise at room temperature while stirring, and the mixture was allowed to stand for 5 minutes.

(The start of the reaction is confirmed when the color of iodine disappears and heat is generated)
. Next, a mixed solution consisting of 51.7 g of furfural 48.0f13-chloro-1-butene and 144.0f1 of toluene was added dropwise over 3 hours at a reaction temperature of 15°C with stirring, and then maintained at the same temperature for 2 hours. did.

After completion of the reaction, this reaction solution and 15.0 wt% sulfuric acid aqueous solution 1
47.1f in 211f of water at 20°C with stirring to pH 8.
It took 12 minutes to maintain the above amount, and then 20 wt.
% acetic acid aqueous solution was added dropwise to lower the pH to 5, and then the 4 powders were maintained at the same temperature.

After the reaction was completed, the reaction solution was separated into an oil layer and an aqueous layer.

The aqueous layer was extracted with 150y of toluene, the toluene layer was added to the oil layer, and the oil layer was washed with a 5 wt % aqueous sodium carbonate solution, and then the solvent was distilled off. Next, vacuum distillation (90-93.
5 soluble C/2.0 x 1 (PPa) and 2-(1-hydroxy-2-methyl-3-butenyl)-furan 75.1 gr
′ was obtained. The yield based on furfural was 98.7%, and the yield based on magnesium was 82.2%. Comparative Example 1 Magnesium shavings 13.5y were placed in a reaction vessel in a nitrogen stream.
1 Tetrahydrofuran (water concentration 300 ppm) 55.
1y and 0.15f of iodine were added, 2.8y of allyl chloride was added dropwise at room temperature while stirring, and the mixture was left to stand for 5 minutes.

(The start of the reaction is confirmed by the disappearance of the color of iodine and the generation of heat). Next, allyl chloride 43.1V and toluene 165.2V
A mixed solution consisting of f was added dropwise under stirring at a reaction temperature of 40C over a period of 4 hours.

Next, 55.0 f of 5-methylfurfural was added dropwise over 1 hour at a reaction temperature of 40 C while stirring, and then maintained at the same temperature for 1 hour. After the reaction is completed, this reaction solution and 15.0W
121f of t% sulfuric acid aqueous solution was added to 211f of water under stirring for 40 minutes.
It took three times to keep the pH at 8 or above at C, and then 5 f of a 20 wt% acetic acid aqueous solution was added dropwise to lower the pH to 5 and hold at the same temperature for 1 hour. After the reaction, 2-(1-hydroxy-3-butenyl)-5 was prepared in the same manner as in Example 1.
- 46.6f of methylfuran was obtained.

The yield based on 5-methylfurfural was 61.2%, the yield based on magnesium was 55.1%, and the conversion rate of the raw material 5-methylfurfural was 90%.

Claims (1)

[Claims] 1 Furfural represented by the general formula ▲ Numerical formula, chemical formula, table, etc. ▼ (in the formula, R_1 represents a hydrogen atom or a methyl group), magnesium and allyl chloride or α-methylallyl chloride After the reaction, it is hydrolyzed to form the general formula▲mathematical formula, chemical formula, table, etc.▼(In the formula, R_1 has the same meaning as above, R_
2 represents an allyl group or an α-methylallyl group), a mixed solvent of tetrahydrofuran and an aromatic hydrocarbon is used as a reaction solvent, and magnesium is added to the above mixed solvent. A method for producing furfuryl alcohols represented by the above general formula, which comprises simultaneously reacting furfural represented by the above general formula with allyl chloride or α-methylallyl chloride.