JPH0215548B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an improvement in a method for producing 2,3-dihydro-2,2-dimethyl-7-hydroxybenzofuran using ortho-methallyloxyphenol as a raw material. 2,3-Dihydro-dimethyl-7-hydroxybenzofuran is a compound known as a raw material for carbofuran insecticides, and it is known that carbofuran is produced by methyl carbamate conversion of this compound. Conventionally, 2,3-dihydro-2,2-dimethyl-7- which is made from ortho-methallyloxyphenol (hereinafter referred to as monoether)
Various methods for producing hydroxybenzofuran (hereinafter referred to as benzofuranol) have been developed. In general, benzofuranol is, for example,
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 investigated, and JP-A-55-76870 proposed a method of heating a monoether in the presence of water and, if necessary, an organic solvent;
JP-A-56-16484 describes a method of heating isobutenylpyrocatechol in the presence of sulfonic acid,
No. 56-29584, a method has been developed in which the etherification, rearrangement, and cyclization reactions of pyrocatechol are carried out in the presence of a specific polyhydroxyalkyl ether. The inventors of the present invention have thoroughly studied the above-mentioned conventional methods, and have also conducted intensive studies aimed at further improving the overall yield from monoether to benzofuranol. Using one or more selected from aliphatic hydrocarbons,
We discovered that benzofuranol can be obtained in high yield by using a halide as a catalyst, and established an economically superior method. That is, the present invention uses one or more selected from water, aromatic hydrocarbons and aliphatic hydrocarbons as a solvent, and ammonia, magnesium, calcium, 2,3-dihydro-2,2- characterized by using a halide of zinc, iron, cobalt or nickel
The present invention relates to a method for producing dimethyl-7-hydroxybenzofuran. The above rearrangement and cyclization reaction of the present invention is shown by the following reaction formula. The solvent in the present invention is one or more selected from water, aromatic hydrocarbons, and aliphatic hydrocarbons. Specific examples of aromatic hydrocarbons and aliphatic hydrocarbons include benzene, toluene, xylene,
Examples include ethylbenzene, cymene, cymene, hexane, 3-methyl-pentane, heptane, octane, nonane, decane, undecane, dodecane, tridecane, cyclohexane, cycloheptane, cyclooctane, cyclononane, decalin, tetralin, naphthalene, and the like. In the present invention, no effect was observed in organic solvents such as acetic acid, N,N-dimethylformamide, alcohols, and nitrophenol used in place of the hydrocarbon. In addition, when using a catalyst in the absence of a solvent, or in the presence of the hydrocarbon and water,
When no catalyst was used, the yield remained low compared to the method of the present invention. Although the hydrocarbon and water can be used alone, it is more preferable to use both in combination. In particular, it is preferable to use both hydrocarbons together in a range where the volume ratio of hydrocarbon to water exceeds 3, and it is particularly preferable to use water at a mixing ratio of 10 to 20% (by volume). The amount of the solvent used in the present invention is preferably about 1 to 50 parts by weight, particularly preferably about 3 to 20 parts by weight, per 1 part by weight of the monoether. In the present invention, halides are used as catalysts. Examples of halides include chlorides and bromides, with chlorides being particularly preferred; specific examples include chlorides of ammonia, magnesium, calcium, zinc, iron (divalent and trivalent), cobalt, and nickel; Among these, chlorides with water of crystallization are effective whether or not they have water of crystallization, and there is no discernible difference. The amount of the catalyst used in the present invention is about 0.01 to 2% by weight, preferably about 0.05 to 0.9% by weight, based on the total amount of the reaction solution. The present invention is generally about 150 to 250°C, preferably about
It is carried out in a temperature range of 190-210 °C. Moreover, either a batch method or a continuous method can be used. Furthermore, the present invention provides intermediate rearrangement products from monoethers, such as 3-methallyl-1,2-dihydroxybenzene and 3-isobutenyl-
Although benzofuranol is produced through 1,2-dihydroxybenzene, benzofuranol is produced directly from monoether in a simple and high yield in a one-step process without any purification process for these intermediates. This provides a method to do so. Next, embodiments of the present invention will be specifically described. The monoether, the solvent, and the catalyst may be added in any order and then heated, or the monoether or the mixture of the monoether and the solvent may be added to the heated mixture of the solvent and the catalyst. The reaction rate of the present invention is fast, and the reaction is usually completed in about 30 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 also be directly subjected to the reaction without isolation. On the other hand, the catalyst can be separated into the aqueous phase. It is possible to use it repeatedly. Next, the present invention will be explained with reference to Examples. Example 1 Monoether was placed in a 300 ml glass-lined autoclave equipped with a thermometer and a stirring device.
16.4g (100mmol), toluene 164ml, water 40ml
Add 0.2 g of calcium chloride dihydrate and replace the air in the system with nitrogen gas. Next, the mixture was heated at 200° C. for 2 hours with stirring and cooled. As a result of high performance liquid chromatography analysis of this reaction solution,
13.12 g (80 mmol) of benzofuranol were obtained (yield 80%). Further, the nuclear magnetic resonance spectrum and mass spectrum of the fraction obtained by distilling the oil layer of this reaction solution under reduced pressure completely matched the spectrum of benzofuranol, which was synthesized separately, and the identity was confirmed. Examples 2 to 5 The reaction was carried out in the same manner as in Example 1 except for changing the type of catalyst. The results are shown in Table 1. Note that the yield represents the mol% of the produced benzofuranol relative to the monoether used.

[Table] Example 6 Monoether 16.4g (100 mmol), dodecane
The same procedure as in Example 1 was conducted using 164 ml, 20 ml of water, and 0.2 g of zinc chloride. As a result of the reaction, the yield of benzofuranol was 81%. Example 7 The same procedure as in Example 1 was carried out using 16.4 g (100 mmol) of monoether, 48 ml of water, and 0.2 g of zinc chloride. As a result of heating at 200°C for 1 hour, the yield of benzofuranol was 77%. Example 8 16.4 g (100 mmol) of monoether, 164 ml of tetrahydronaphthalene and ferric chloride hexahydrate
The same procedure as in Example 1 was carried out using 0.2 g. As a result of the reaction, the yield of benzofuranol was 76%.

Claims (1)

[Claims] 1. 2,3-dihydro-2,2 by rearrangement and cyclization reaction of ortho-methallyloxyphenol
- When obtaining dimethyl-7-hydroxybenzofuran, the solvent is water, one or more selected from aromatic hydrocarbons and aliphatic hydrocarbons, and the catalyst is ammonia, magnesium, calcium, zinc, iron, cobalt, or a halogen of nickel. 1. A method for producing 2,3-dihydro-2,2-dimethyl-7-hydroxybenzofuran, characterized by using a compound. 2 Using a mixed solvent of water and hydrocarbon as a solvent,
The method according to claim 1, characterized in that the volume ratio of hydrocarbon to water exceeds 3.