JPS583035B2 - Method of oxidizing paraphenoxytoluene - Google Patents

Description

Detailed Description of the Invention The present invention relates to a method for oxidizing paraphenoxytoluene, and more specifically, paraphenoxytoluene is electrolytically oxidized in acetic acid to produce paraphenoxybenzaldehyde and/or paraphenoxybenzaldehyde.
The present invention relates to a method for oxidizing paraphenoxytoluene, which is characterized by obtaining paraphenoxybenzyl acetate.

Many studies have been conducted to oxidize either side chains or aromatic nuclei by acting various high-valent metal salts on alkyl-substituted benzenes, but these studies are not always satisfactory in terms of yield, selectivity, etc. No results have been obtained.

As a result of research on the electrolytic oxidation of metaphenoxytoluene and paraphenoxytoluene, the present inventors found that it is difficult to increase the conversion rate when metaphenoxytoluene is electrolytically oxidized in acetic acid. As a product, a nuclear acetoxide and a small amount of metaphenoxybenzaldehyde are obtained, whereas electrolytic oxidation of paraphenoxytoluene in acetic acid easily achieves a high conversion rate and produces oxidation products of side chain methyl groups. It was discovered that (paraphenoxybenzaldehyde and/or paraphenoxybenzyl acetate) can be obtained with good selectivity, leading to the present invention.

The method of the present invention can be expressed by the following equation.

That is, when paraphenoxytoluene (■) is electrolytically oxidized in acetic acid, paraphenoxybenzyl acetate (■) is first produced, and this paraphenoxybenzyl acetate (■) is further oxidized to form paraphenoxybenzaldehyde (III). is generated.

Normally, the oxidation of paraphenoxybenzyl acetate generated before the conversion rate of paraphenoxytoluene becomes sufficiently high occurs, and even when the reaction time is relatively short, paraphenoxybenzyl acetate and paraphenoxybenzaldehyde are As the reaction time increases, the conversion rate of paraphenoxytoluene increases and the amount of paraphenoquine benzaldehyde in the product increases.

For this reason, the process of the invention is particularly suitable for the production of paraphenoxybenzaldehyde.

The electrolytic oxidation according to the present invention uses, for example, a platinum electrode as an electrode, in acetic acid, (C2H5)4NC104, (
C2H5)4NNO3, and CH3COONa, and can be carried out at about 20 DEG C. to about 50 DEG C. (usually at ambient temperature).

The supporting electrolyte concentration in acetic acid is typically about 10 per liter of acetic acid.
A suitable amount is about 15 g to about 15 g.

The concentration of paraphenoxytoluene is approximately 10g per liter of acetic acid.
~about 30g is preferred.

If the terminal voltage is too high, the nuclear acetoxylation reaction will take priority, so the terminal voltage is preferably about 15 volts or less, preferably 5 to 10 volts.

In addition to containing the above-mentioned components, the electrolyte may contain other components as long as they do not cause any harm.

After the electrolytic oxidation reaction, for example, acetic acid is distilled off under reduced pressure, an appropriate amount of water is added to the residue, this is extracted with a benzene-ether mixed medium, etc., and the extract is treated by a commonly used separation method. By doing so, the desired product can be separated and obtained.

Paraphenoxybenzyl acetate and paraphenoxybenzaltehyde obtained by the method of the present invention are both industrially useful substances, such as paraphenoxybenzyl acetate itself, hydrolysis of paraphenoxybenzyl acetate, and paraphenoxybenzaltehyde. Paraphenoxybenzyl alcohol obtained by reduction of sibenzaldehyde is used as the alcohol component of pyrethroid insecticidal compounds.

The present invention will be explained below using examples.

Example 1 184 mg of paraphenoxytoluene, 115 mg of (CH2)4NCl and C
41 mg of H3COONa was weighed out and dissolved in 13 ml of acetic acid (distilled acetic acid).

Two platinum plates (1.5 x 2 cm2) were used as electrodes, and while stirring with a magnetic stirrer, the voltage was 3 volts (V), and the current direction was changed every 30 seconds at 25°C for 24 hours or 48 hours. Constant current electrolysis was performed.

After electrolysis, remove as much acetic acid as possible using a rotary evaporator, add a small amount of water, and add 5ml of benzene-ether (1:1) mixed solvent using a 50ml separating funnel.
Extracted 3 times with l.

After separating the organic layer and washing it three times with saturated saline,
Drying over Na2SO4 and evaporation of the medium in vacuo yielded approximately 195-200 mg of crude product as an oil.

This product was purified using a silica gel column as follows.

First, unreacted paraphenoxytoluene was removed using hexane, and then the developing solvent was changed to hexane-ethyl acetate (20:1
) When the fraction with Rf0.4 was separated instead of the mixture, paraphenoxybenzyl acetate and paraphenoxybenzaldehyde were obtained.

The amount of recovered unreacted paraphenoxytoluene and the amount of isolated reaction product were as shown in the following table when the reaction time was 24 hours and when the reaction time was 24 hours.

The infrared absorption spectrum and nuclear magnetic resonance spectrum of the obtained paraphenoxybenzyl acetate and paraphenoxybenzaldehyde were as follows.

Paraphenoxybenzyl acetate Examples 2 to 3 and Reference Examples 1 to 4 Using two platinum plates (3 cm2) as electrodes, metaphenoxytoluene and paraphenyl Enoxytoluene was electrolytically oxidized and post-treated in the same manner as in Example 1 to obtain the results shown in the following table.

Solvent: 13 ml of acetic acid, current: 0.05 to 0.1 A In Table 2, raw materials ■ and ■ and products ■, ■,
■, ■ and ■ respectively mean the following compounds, Et
represents an ethyl group, and Ac represents an acetyl group.

Claims (1)

[Claims] 1. A method for oxidizing paraphenoxytoluene, which comprises electrolytically oxidizing paraphenoxytoluene in acetic acid to obtain paraphenoxybenzaldehyde and (c) paraphenoxybenzyl acetate.