JPH0251414B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a novel method for producing 1-phenyl-2-alkoxyalkenes. 1-phenyl-2-alkoxyalkenes are
It has many industrial uses as an intermediate raw material for various agricultural chemicals, fragrances, and pharmaceuticals. The present inventors conducted extensive research with the aim of establishing a new method for producing 1-phenyl-2-alkoxyalkenes. As a result, the general formula (); (However, X, Y, and Z each represent a substituent selected from the group consisting of a hydrogen atom, a hydroxyl group, a halogen atom, a lower alkyl group, and a lower alkoxy group,
X, Y, and Z may be the same or different; It may form a 7-membered heterocycle. Moreover, R represents a lower alkyl group. ) is reacted with alcohol in the presence of an acid and a dehydrating agent,
General formula (); (However, X, Y, Z and R have the same meanings as above, and R' represents the alkyl residue of the alcohol used.)
- It has been discovered that alkoxyalkenes can be produced industrially advantageously, and the present invention has been completed. In the benzyl-alkyl-ketones represented by the general formula () which are the raw materials of the present invention,
Among the substituents represented by X, Y and Z, halogen atoms include chlorine, bromine, fluorine and iodine, and lower alkyl groups have 1 to 4 carbon atoms such as methyl, ethyl, propyl and butyl. Alkyl groups can be mentioned,
Furthermore, examples of lower alkoxy groups include methoxy, ethoxy, propoxy, and butoxy having a carbon number of 1.
Mention may be made of alkoxy groups having ˜4. Examples of the lower alkyl group represented by R include alkyl groups having 1 to 4 carbon atoms such as methyl, ethyl, propyl, and butyl. These benzyl-alkyl-ketones are easily obtained, for example, by reacting phenyl alkenes with alkyl nitrite esters in the presence of alcohol and palladium salt catalysts, and then hydrolyzing the reaction product with water. be able to. This reaction uses about 2 to about 5 moles of alkyl nitrite and about 1 to about 10 alcohols per mole of phenyl alkene, and optionally acetic acid in the presence of a palladium salt such as palladium chloride. In a solvent such as an ester, at a temperature of about 5 to about 150°C, normal pressure to
It can be carried out at a pressure of about 20 kg/cm ² (gauge). Alcohols that can be used in the present invention include methanol, ethanol, propanol,
Mention may be made of aliphatic alcohols having 1 to 6 carbon atoms, such as butanol, amyl alcohol and hexanol. The amount of alcohol to be used is 1 to 50 mol, preferably 2 to 10 mol, per 1 mol of the raw material benzyl-alkyl-ketone. Examples of the acid used as a catalyst in the present invention include sulfonic acids such as para-toluenesulfonic acid, and mineral acids such as hydrochloric acid and sulfuric acid. These acids are based on the benzyl-alkyl-
The amount used is usually 0.0001 to 0.02 mol, preferably 0.0003 to 0.01 mol, per 1 mol of ketones. Further, examples of the dehydrating agent that can be used in the present invention include acetone dimethyl acetal, orthoformic acid ester, and acetic anhydride. When these dehydrating agents are used in too small an amount, the reaction proceeds insufficiently, and on the other hand, even when used in a large amount, the reaction is not adversely affected, but it is uneconomical to use more than the necessary amount. In view of these, 1 to 10 mol of dehydrating agent, preferably 1.05 mol, of the dehydrating agent is added to 1 mol of benzyl-alkyl-ketones as raw materials.
It is preferable to use ~3 mol. The solvents used in the present invention include:
Any material may be used as long as it dissolves the raw material benzyl-alkyl-ketone well and is substantially inert to the reaction. Specific examples of such substances include aromatic hydrocarbons such as benzene, toluene, and xylene, lower fatty acid esters such as ethyl acetate and butyl acetate, ethers such as tetrahydrofuran and dioxane, and mixed solvents thereof. . These solvents are usually used in an amount of about 5 to 50 parts by weight per 1 part by weight of the raw material benzyl-alkyl-ketone. In addition, the reaction in the present invention is usually about 60 to about
The process is carried out at a temperature of 150° C. and under normal pressure for about 1 to 5 hours. After the completion of the reaction, the target product 1-
Phenyl-2-alkoxyalkenes can be isolated and obtained. Next, examples of the present invention will be given. Note that the benzyl-alkyl-ketones used as raw materials in each example were all manufactured according to the following synthesis example. In addition, the reaction rate and yield of the target product in each example were calculated using the following formula. Reaction rate (%) = (Number of moles of reacted benzyl-alkyl-ketones/Number of moles of benzyl-alkyl-ketones charged) x 100 Yield (%) = (1-phenyl-2-alkoxyalkenes produced (number of moles of benzyl-alkyl-ketones charged) x 100 Synthesis example 3-(4-methoxyphenyl)propylene 0.10
mole, methyl nitrite 0.25 mole, methyl alcohol
0.5, and 0.006 mol of palladium chloride as a catalyst were charged into a reaction vessel, the reaction temperature was 20°C, and the reaction time was 1.5.
After the reaction was carried out under the conditions of 1 hour, 0.1 hour of water was added and hydrolysis was carried out at about 20°C for 0.5 hour. After hydrolysis,
The reaction solution was vapor-deposited to obtain 4-methoxyphenylacetone with a yield of 90%. Examples 1 to 7 After dissolving 0.1 mol of benzyl-alkyl-ketones as shown in Table 1 in 0.3 mol of benzene, 0.12 mol of acetone dimethyl acetal and methanol were added.
0.24 mol and catalyst para-toluenesulfonic acid
0.0005 mol was added and the reaction was carried out at 80°C for 3 hours.
After the reaction was completed, the unreacted raw materials in the reaction solution and the produced target product, 1-phenyl-2-alkoxyalkenes, were quantitatively analyzed by gas chromatography. The results are shown in Table 1.

【table】

[Table] Example 8 After dissolving 0.10 mol of 3,4-dimethoxyphenylacetone in 0.3 mol of toluene, 24 mol of methanol
0.0005 mol of p-toluenesulfonic acid and 0.12 mol of methyl orthoformate were added, and the reaction was carried out at 80°C for 3 hours. After the reaction was completed, unreacted raw materials and products in the reaction solution were quantitatively analyzed by gas chromatography. As a result, the reaction rate of the raw material 3,4-dimethoxyphenylacetone was 93%, and the target product 1-
The yield of (3,4-dimethoxyphenyl)-2-methoxypropylene was 81%. Example 9 An experiment was carried out in the same manner as in Example 8, except that 0.12 mol of acetic anhydride was used instead of orthoformate as a dehydrating agent. As a result, the reaction rate of the raw material 3,4-dimethoxyphenylacetone was 71%, and the target product 1-
The yield of (3,4-dimethoxyphenyl)-2-methoxypropylene was 51%.

Claims (1)

[Claims] 1 General formula (); (However, X, Y, and Z each represent a substituent selected from the group consisting of a hydrogen atom, a hydroxyl group, a halogen atom, a lower alkyl group, and a lower alkoxy group,
X, Y, and Z may be the same or different; It may form a 7-membered heterocycle. Moreover, R represents a lower alkyl group. General formula (), characterized by reacting benzyl-alkyl-ketones represented by ) with alcohol in the presence of an acid and a dehydrating agent: (However, X, Y, Z and R have the same meanings as above, and R' represents the alkyl residue of the alcohol used.)
-Production method of alkoxyalkenes.