JPS6160835B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing 2,3-dihydro-2,2-dimethyl-7-hydroxybenzofuran using ortho-methallyloxyphenol as a raw material. 2,3-dihydro-2,2-dimethyl-7-
Hydroxybenzofuran is a compound known as a raw material for carbofuran insecticides, and it is known that carbofuran is produced by converting this compound into methyl carbamate. Conventionally, 2,3-dihydro-2,2-dimethyl-7 is produced from ortho-methallyloxyphenol (hereinafter also referred to as monoether).
- Various methods for producing hydroxybenzofuran (hereinafter also referred to as benzofuranol) have been developed. Generally, benzofuranol is
7223 and Special Publication No. 42-12263,
It has been synthesized by heating monoether to about 200°C, but the yield in this case was low and did not reach 50%. Subsequently, these improved methods were studied, and JP-A-55-76,870 proposed a method in which monoether was heated to 170-230°C in the presence of water and an organic solvent if necessary, and JP-A-56-16,484 proposed an iso- Butenylpyrocatechol in the presence of sulfonic acid from 60 to
A method of heating to 200 DEG C. and a method of carrying out etherification, rearrangement and cyclization reactions of pyrocatechol in the presence of a specific polyhydroxyalkyl ether have been developed in JP-A-56-29584. The inventors of the present invention have thoroughly investigated the above-mentioned conventional method, and as a result of intensive studies aimed at further improving the overall yield from monoether to benzofuranol, they have found that aluminum iodide or aluminum chloride can be used as a catalyst. We have established a method for economically producing benzofuranol in high yield by using an N-substituted aniline derivative or a complex of both compounds. That is, the present invention provides for obtaining 2,3-dihydro-2,2-dimethyl-7-hydroxybenzofuran by rearrangement and cyclization reaction of ortho-methallyloxyphenol, using aluminum iodide or aluminum chloride as a catalyst and the general formula (In the formula, R ¹ and R ² are alkyl groups having 1 to 6 carbon atoms,
Phenyl group or R ¹ and R ² are bonded and have 5 carbon atoms
-7 alkylene group, R ³ is hydrogen or carbon number 1
2,3-dihydro-2,3-dihydro-
This invention relates to a method for producing 2,2-dimethyl-7-hydroxybenzofuran. The above rearrangement and cyclization reaction of the present invention is shown by the following reaction formula. In the present invention, aluminum iodide or aluminum chloride, an N-substituted aniline derivative represented by the general formula (1), or a complex of these two compounds are used as a catalyst. As the above complex, aluminum iodide or aluminum chloride and an N-substituted aniline derivative may be added separately to form a complex in the system, or a complex of both compounds synthesized in advance may be used. good. A complex of aluminum iodide or aluminum chloride and an N-substituted aniline derivative is usually formed by using the latter in a ratio of about 1 mol or more per 1 mol of the former. Aluminum iodide is preferably used in a proportion of about 0.001 to 0.8 parts by weight, particularly preferably about 0.008 to 0.08 parts by weight, per part by weight of monoether. Aluminum chloride is preferably used in an amount of about 0.001 to 0.5 per part by weight of monoether.
Parts by weight are used, particularly preferably from about 0.005 to 0.05 parts by weight. Aluminum iodide and aluminum chloride can be used even in the presence of water of crystallization, but anhydrous forms are preferred. Suitable examples of the N-substituted aniline derivative represented by general formula (1) include N,N-dimethylaniline, N,N-diethylaniline, N-methyl-diphenylamine, N,N-
-dimethyl-p-toluidine, N-phenylpiperidine, and the like. In the present invention, the reaction can preferably be carried out using a solvent. The solvent used is not particularly limited, but suitable solvents include N-substituted aniline derivatives represented by the above general formula (1), aromatic hydrocarbons, aliphatic hydrocarbons, aromatic ethers,
Mention may be made of aliphatic ethers, aromatic ketones, and aliphatic ketones. Specific examples of the aromatic hydrocarbons mentioned above include benzene, toluene, xylene, diethylbenzene, triethylbenzene, mesitylene, kyumene, cymene, amylbenzene, naphthalene, tetralin, diphenylethane, etc., and specific examples of the aliphatic hydrocarbons include hexane and heptane. Examples of aromatic or aliphatic ethers include diphenyl ether, anisole, butyl phenyl ether, etc. Specific examples of group or aliphatic ketones include benzophenone, acetophenone, p
- Hydroxyacetophenone, acetone, methyl isobutyl ketone, cyclohexanone, etc. can be mentioned. Such solvents can be used alone or in combination, and are usually about 1 to 50 parts by weight, preferably about 5 to 25 parts by weight, per 1 part by weight of monoether.
Used in parts by weight. The present invention is generally about 60 to 250°C, preferably about 100°C.
Performed in a temperature range of ~210°C. Moreover, either a batch method or a continuous method can be used. In the present invention, benzofuranol is produced from a monoether through an intermediate rearrangement product, that is, 3-methallyl-1,2-dihydroxybenzene or 3-isobutenyl-1,2-dihydroxybenzene. However, the present invention provides a method for producing benzofuranol directly from monoether in a simple and high yield in a one-step process without providing a purification step for these intermediates. Furthermore, a major feature of the present invention is that although either normal pressure or pressurized methods can be adopted in the present invention, performing the reaction at normal pressure allows the equipment to be simplified and is economical. Benzofuranol can be produced in a high yield. Next, embodiments of the present invention will be specifically described. Monoether, catalyst, and solvent may be added in any order and then heated, or aluminum iodide or aluminum chloride and general formula (1)
After the N-substituted aniline derivatives represented by are mixed to form a complex, a solvent and a monoether may be added and heated. The reaction rate of the present invention is fast, and the reaction is usually completed in several tens of minutes to several hours. After the reaction, the obtained benzofuranol can be isolated by distillation or the like, and when another compound is further synthesized using benzofuranol as a raw material, it can be directly subjected to the reaction without isolation. The present invention will be explained below with reference to Examples. Example 1 Capacity with thermometer, stirrer and reflux condenser
200 g of N,N-dimethylaniline is placed in a 300 ml glass reactor, and the air in the system is replaced with nitrogen gas. Then aluminum iodide
Add 0.6g and stir. Monoether 16.4 to this
g (100 mmol) and heated at reflux temperature for 1 hour with stirring. As a result of high performance liquid chromatography analysis of this reaction solution, 13.8 g (84 mmol) of benzofuranol was obtained. Further, as a result of measurement of the nuclear magnetic resonance spectrum and mass spectrum of the fraction obtained by distilling this reaction solution under reduced pressure, the spectrum completely matched that of a separately synthesized standard benzofuranol, and the identity was confirmed. Examples 2 to 6 Using the same reactor as in Example 1, the system was placed under a nitrogen gas atmosphere, and 16.4 g (100 mmol) of monoether, an N-substituted aniline derivative, and aluminum iodide or aluminum chloride were sequentially added. Stir. This mixture was heated and the results in Table 1 were obtained.

【table】

[Table] Comparative Example 1 When the same procedure as in Example 1 was carried out except that aluminum iodide was not used, the yield of benzofuranol was extremely low at 5%. Examples 7 to 10 Using the same reactor as in Example 1, 16.4 g (100 mmol) of monoether, N,N-dimethylaniline, a solvent, and aluminum iodide or aluminum chloride were added in sequence under a nitrogen gas atmosphere. Stir. This mixture was heated and Table 2
The results were obtained.

[Table] Example 11 A glass-lined autoclave with a capacity of 300 ml equipped with a thermometer and a stirring device was placed under a nitrogen gas atmosphere, and 16.4 g (100 mmol) of monoether, 1.0 g of N,N-dimethylaniline, 100 g of mesitylene and 0.5 g of aluminum iodide are sequentially added and stirred. When this mixture was heated at 200°C for 2 hours, the yield of benzofuranol was 78%. Example 12 Toluene was used instead of mesitylene in Example 11.
The same procedure was carried out except that 100 g was used, and the yield of benzofuranol was 78%.

Claims (1)

[Claims] 1. 2,3-dihydro-2,2 by rearrangement and cyclization reaction of ortho-methallyloxyphenol
- When obtaining dimethyl-7-hydroxybenzofuran, aluminum iodide or aluminum chloride and the general formula (In the formula, R ¹ and R ² are alkyl groups having 1 to 6 carbon atoms,
Phenyl group or R ¹ and R ² are bonded and have 5 carbon atoms
-7 alkylene group, R ³ is hydrogen or carbon number 1
2,3-dihydro-2, characterized in that it uses an N-substituted aniline derivative represented by (indicating an alkyl group of ~3) or a complex of both of these compounds.
Method for producing 2-dimethyl-7-hydroxybenzofuran. 2. Claim 1 in which one or more selected from aniline derivatives represented by the above general formula (1), aromatic hydrocarbons, aliphatic hydrocarbons, aromatic ethers, and aliphatic ethers are used as a solvent Manufacturing method described. 3. The process according to claim 1, wherein the reaction is carried out at a temperature range of about 60-250°C.