JPS61152637A - Production of p-methylphenacyul halide - Google Patents

Abstract

PURPOSE:To obtain advantageously the aimed compound in high selectivity and yield, by using a lower alcohol as a solvent in producing the titled compound useful as an intermediate for herficides through reaction of p- methylacetophenone with a halogenating agent in the solvent. CONSTITUTION:p-Methylacetophenone is reacted with a halogenating agent, preferably bromine or chlorine gas, in a lower alcohol such as methanol, ethanol, propanol and butanol (methanol and/or ethanol are preferred) at 0-50 deg.C, preferably 54n30 deg.C to obtain a p-methylphenacyl halide in extremely high selectivity and yield with supressing disproportionation reaction without using any troublesome operation such as recrystallization. The amount of the solvent to be used is 5-15mol, preferably 6.5-10mol and the amount of the halogenating agent to be used is 0.9-1.1mol, preferably equimolar, both based on 1mol p- methylacetophenone.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a method for producing p-methyl 7-enacylnolide.

According to the method of the present invention, the target p-methylphenacyl halide can be produced in extremely high yield.

The p-methylphenacyl halide obtained by the method of the present invention exhibits excellent effects as an active ingredient of herbicides.
It is an industrially useful compound, serving as a raw material for 3-dimethyl-4-(2,4-dichloro-3-methylbenzoyl 3-s-(4-methylphenacyloxy)pyrazole).

Sales technology The production method of p-methyl phenacyl halide is p-
A method in which methylacetophenone and a halogenating agent are reacted in a solvent such as acetic acid, a halogenated hydrocarbon, an aromatic hydrocarbon, etc. (for example, Fritz Krgnk
e Ber, 69 B, 921 (tsas)
), or a method in which an acid catalyst such as aluminum chloride is further added to this reaction system (for example, W, S, Nat
han and H-B-Watson J,
Chem-8oc, 1933.217-220, etc.) are known.

However, in the above method, the target product p-
Methyl phenacyl halide undergoes a disproportionation reaction in the reaction solution, producing raw materials p-methylacetophenone and cybaride. Therefore, for example, if 1 mole of halogenating agent is added to 1 mole of p-methylacetophenone, the reaction solution will be reduced to 0.0% of p-methylacetophenone in about 1 hour at room temperature.
．． 1 mol, p-methylphenacyl halide 0.8 mol,
The equilibrium composition is 0.1 mole of sybaride. As a result, the reaction yield was as low as 80% (1% p-methylacetophenone, 10% cybalide). For this reason, it was necessary to use operations such as recrystallization to further purify the target product, which became complicated and further reduced the yield (isolated yield 60%, purity 99.9%). ).

Therefore, there has been a need for a high-yield production method that suppresses the above-mentioned disproportionation reaction.

Summary of the Invention The present invention provides a method for producing p-methylphenacyl halide by reacting p-methylacetophenone and a halogenating agent in a solvent, characterized in that the solvent is a lower alcohol. - A method for producing methyl phenacyl halide is provided.

Effects of the Invention According to the method of the present invention, p-methylphenacyl halide does not undergo a disproportionation reaction in the reaction solution, so extremely high selectivity and yield can be achieved without complicated operations such as recrystallization. The desired p-methylphenacyl halide can be produced.

DETAILED DESCRIPTION OF THE INVENTION The method of the present invention is carried out by adding a halogenating agent to a mixed solution of p-methylacetophenone and a lower alcohol.

As the lower alcohol, Cl-4 alcohol,
For example, methanol, ethanol, propatool, butanol, etc. are used, and methanol and/or ethanol are particularly preferred from the viewpoint of yield.

The halogenating agent is not particularly limited, but bromine or chlorine gas is preferred from the standpoint of separation from the target product.

In the method of the invention, the reaction is carried out at a temperature range of 0 to 50°C, preferably 5 to 30°C.

The amount of the above solvent used is usually p-methylacetophenone 1
5 to 15 times the mole, preferably 6.5 to 10 times the mole
It is twice the mole. The amount of the halogenating agent used is 0.9 to 161 mol, preferably equimolar, relative to p-methylacetophenone, and the halogenating agent is added dropwise usually in 15 to 120 minutes. After the dropwise addition is complete, the reaction solution is poured into ice water and conventional separation operations such as crystallization and filtration are performed to obtain p-methylphenacyl halide, which is the target product with a purity of 991 or more.
% (in terms of p-methylacetophenone).

Experimental Examples Example 1 In a four-way flask equipped with a thermometer, reflux condenser, stirrer, and dropping funnel, p-methylacetophenone 21
．． i p (157.2 mmol) and methanol 47.
ap (14 os mmol) was added.

While stirring and keeping the temperature at 5-10°C, add 25% bromine.
2y (157.5 mmol) was added dropwise over about 60 minutes. Stirring was continued for about 60 minutes after the dropwise addition was completed. After the reaction was completed, analysis by gas chromatography revealed that this product contained 97.7% p-methylphenacylbromide and 2% other
．． It was found that it contains 31.

Further, when the reaction product was poured into 100 d of ice water, white crystals were precipitated. After separating the crystals from P, they were dried under reduced pressure at 25-30°C to obtain crystals a1.5sP (t4s, s mmol) (yield 94.5%, purity 99.11).

Example 2 Crude p-methylacetophenone (pure & 94.1%) as raw material
Example 1 except that 2.8% o-methylacetophenone and 3.0% m-methylacetophenone were used.
The reaction was carried out in the same manner as in the above case, and after the reaction was completed, analysis by gas chromatography revealed that p-methylphenacylbromide was 92%1.

- and m-methylphenacylpropa)' and 2.31% of others.

In addition, this reaction product was post-treated in the same manner as in Example 1, and recrystallized from n-hexane to give crystals 2s, sp
(1s 3.4 mmol) was obtained. (Yield 90.2cm,
Purity: 99.41) Example 3 The reaction was carried out in the same manner as in Example 1 except that the reaction temperature was 5 to 25°C, and the obtained reaction product was analyzed by gas chromatography. It was found that it contained 9λ1 of phenacylbromide and 6.9 of others.

Further, this reaction product was treated in the same manner as in Example 1 to obtain 30.97 y (t 4 a, a mmol) of crystals (yield 9x, s%, purity 99.0 t).

Example 4 The reaction was carried out in the same manner as in Example 1 except that methanol was replaced with ethanol, and the resulting reaction product was analyzed by gas chromatography. It was found that it contained 6.9 regrets.

Further, this reaction product was treated in the same manner as in Example 1 to obtain crystals a 1.2 F (144.9 mmol) (yield 92.2, purity 99.0).

Example 5 The reaction was carried out in the same manner as in Example 1 except that bromine gas was replaced with chlorine gas, and the obtained reaction product was analyzed by gas chromatography, and it was found that p-methylphenacyl chloride sin, p- Methylphenacyl dichloride 2
．． It was found that it contained 3% and 6.3 g of p-methylacetophenone. 9. This reaction product was treated in the same manner as in Example 1 to give 24.3 crystals (143°8 mmol).
(Yield: 90.5%, purity: 99.0%).

Comparative Example 1 In a four-way flask equipped with a thermometer, reflux condenser, stirrer, and dropping funnel, p-methylacetophenone 21
．． 11 (157,2 mmol) and 1,2- as solvent
Dichloroethane zxsy (2203 mmol) was added. While stirring and keeping the temperature at 3-6℃, add bromine 24
．． 9 F (155.6 mmol) was added dropwise over about 60 minutes. After the dropwise addition was completed, stirring was continued for 3 hours at room temperature.

After completion of the reaction, analysis by gas chromatography revealed that this product was p-methylphenacylbromide ys, t
l, o- and m-methylphenacylbromide s, z%,
It was found that it contained 8.9% of p-methylacetophenone, 7.19% of p-methylphenacyl chloride, and 2.7% of others.

Further, the reaction product was washed twice with 400 d of water, dried over magnesium sulfate, the solvent was distilled off, and this product was recrystallized with 42 wt 1 of n-hexane.

The crystals were separated from the furnace and dried under reduced pressure at 25-30°C to obtain yellow-green crystals 19F (yield: 56.6 yen, purity: 9 g, 9 ts).
.

Comparative Example 2 Anhydrous aluminum chloride 0.189 P(1
The reaction was carried out in the same manner as in Comparative Example 1, except that 1 mol of 4Z Mi) was used.

After completion of the reaction, analysis by gas chromatography revealed that p-methylphenacyl bromide was 79.9To, o-
It was found that it contained 4.4% of m-methylphenacyl bromide, 6.0% of p-methylacetophenone, 7.1% of p-methylphenacyl chloride, and 2.6% of others. Further, this reaction product was treated in the same manner as in Comparative Example 1 to obtain crystals of 20.3 f! (Yield s O, 4'4
, pure 1i99.9%).

Example 6 The reaction was carried out in the same manner as in Example 1 except that methanol was replaced with isopropyl alcohol, and the reaction product was analyzed by gas chromatography. - It was found that it contained 15.3 g of methylacetophenone and 2.25 g of others. Further, this reaction product was treated in the same manner as in Example 1 to obtain crystal 24y (112.6 mmol).
(yield: 70.2%, purity: 98%).

Example 7 The reaction was carried out in the same manner as in Example 1 except that methanol was replaced with n-butanol, and the reaction product was analyzed by gas chromatography. -Methylacetophenone5. +11. It turns out that it includes IZ and S Chi as well as So. In addition, this reaction product was treated in the same manner as in Example 1 to obtain crystal 2L1 (99 mmol) (yield: 61.7 mmol, purity: 98 mmol).

Claims (1)

[Claims] (1) A method for producing p-methylphenacyl halide by reacting p-methylacetophenone and a halogenating agent in a solvent, characterized in that the solvent is a lower alcohol. Halide production method.