JPS6239145B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improved process for the production of 3-phenoxybenzaldehyde, a valuable intermediate in the production of pyrethroid insecticides. Such insecticides include 3-phenoxybenzyl and alpha-cyano-3-phenoxybenzyl esters of substituted cyclopropane carboxylic acids and of chlorophenylacetic acids.

Alpha of substituted cyclopropanecarboxylic acids
One route to cyano-3-phenoxybenzyl esters is to use water, a water-soluble cyanide, a substantially water-immiscible aprotic solvent, and a phase as described in Dutch Patent Application No. 7702022. It involves the reaction of 3-phenoxybenzaldehyde with a substituted acyl halide in the presence of a transferred catalyst. This reaction is a modification of the so-called "Francis reaction" and produces alpha-cyanobenzyl esters in high yields if the starting material 3-phenoxybenzaldehyde is pure, and thus Alpha-cyanobenzyl esters can be easily isolated in high purity from the reaction mixture, for example as a residue by washing the reaction mixture with water and evaporating the aprotic solvent from the washed liquid.

3-Phenoxybenzaldehyde is produced by a modified Sommelet reaction on a mixture of 3-phenoxybenzyl halide and 3-phenoxybenzyl halide, as described in Dutch Patent Application No. 7701128. It can be obtained by This mixture is reacted with hexamethylenetetramine in the presence of aqueous ethanol or aqueous acetic acid, and the resulting reaction mixture is acidified with an aqueous mineral acid;
3-phenoxybenzaldehyde is then isolated from the acidified mixture by standard laboratory procedures such as extraction or steam distillation. Pure 3-phenoxybenzaldehyde can be obtained by distillation of the crude material, and this pure 3-phenoxybenzaldehyde can be successfully used for the Francis reaction.

A disadvantage of the above isolation of pure 3-phenoxybenzaldehyde is that the crude 3-phenoxybenzaldehyde must be distilled at very low pressures (e.g. 120-130°C).
This means that it must be carried out at a pressure of 6.7 Pa). To avoid this extremely low pressure,
Applicants carried out the Francis reaction with the crude (undistilled) 3-phenoxybenzaldehyde, but the 3-phenoxybenzyl ester was obtained in low yield and some of the substituted acyl halides were was found to be converted to a dicyano compound of general formula Q according to the overall formula: Here, R ¹ represents a substituted cyclopropyl or benzyl group.

It has been found that improved purity of undistilled 3-phenoxybenzaldehyde can be obtained that is sufficiently pure to be used directly in the Francis reaction to give high yields of alpha-cyano-benzyl esters.

Therefore, the present invention provides the following steps: (a) treating a mixture of 3-phenoxybenzyl halide and 3-phenoxybenzyl halide in the presence of hexamethylenetetramine and a solvent, and the resulting product (b) removing the solvent from the reaction mixture obtained in step (a); (c) one or more alkanes and/or one or more alkanes; Treating the residue of step (b) with a hydrocarbon solvent consisting essentially of more than 3-
A method for producing 3-phenoxybenzaldehyde is provided, comprising the steps of: producing a hydrocarbon extract phase comprising phenoxybenzaldehyde; and (d) washing the hydrocarbon extract phase with an aqueous solution of a strong acid.

The process according to the invention provides a solution of 3-phenoxybenzaldehyde in a hydrocarbon solvent, and such solution can be used directly in the Francis reaction.

By using an aromatic hydrocarbon solvent in step (c) without using a hydrocarbon solvent consisting essentially of one or more alkanes and/or one or more cycloalkanes, the process yields 3-phenoxybenzaldehyde of poor commercial purity, and if such impure product is used in the preparation of alpha-cyano-benzyl esters, undesirable amounts of dicyano compounds of formula Q are formed. .

The expression "a hydrocarbon solvent consisting essentially of one or more alkanes and/or one or more cycloalkanes" means that the hydrocarbon solvent contains at least 50% by weight of (a) (b) one or more cycloalkanes; or (c) one or more alkanes and one or more cycloalkanes;
It means that. Among the alkanes and cycloalkanes used in step (c), cycloalkanes are more preferred because they have the most favorable effect on the purity of the resulting 3-phenoxybenzaldehyde. Examples of suitable cycloalkanes are cyclopentane, cyclohexane,
Methylcyclohexane, cycloheptane and cyclooctane. The highest purity aromatic aldehydes were obtained in cyclohexane. Examples of mixtures of cycloalkanes are mixtures of cyclohexane and methylcyclohexane and mixtures of cyclooctane and methylcyclooctane. Examples of suitable alkanes are hexane, heptane, octane and nonane and their isomers. An example of a mixture of alkanes is 82°C or more at atmospheric pressure.
It has a boiling point range of 108°C or 107°C to 138°C.

The hydrocarbon solvent used in step (c) is preferably used in an amount ranging from 300 to 1500 ml per mole of benzyl halide and benzal halide mixture.

The strong acid used in step (d) preferably has a dissociation constant in aqueous solution (at 25° C.) of at least 1×10 ⁻⁴ . Examples of suitable strong acids are hydrochloric acid, sulfuric acid and o-phosphoric acid. Very good results were obtained using hydrochloric acid. Appropriately,
At least a 4N aqueous solution is used. The strength of hydrochloric acid is therefore suitably at least 15% by weight
For example, 30% to 40% by weight.

The mixture of 3-phenoxybenzyl halide and 3-phenoxybenzyl halide is conveniently a mixture of chlorides or bromides, but other halides may also be used.

In step (a) of the method according to the invention, the solvent used can be aqueous or non-aqueous. A reaction time of about 2.5 to 3.5 hours is usually required when water is used as the solvent, but non-acidic solvents, especially
If non-acidic solvents containing alkanols with up to 4 carbon atoms per molecule are used, the reaction time is reduced to, for example, 0.5 to 2.5 hours. The alkanol is preferably ethanol. Examples of other suitable alkanols are methanol, propanol, 2-propanol, butanol and 2-methylpropanol. The solvent used in step (a) is preferably an aqueous solvent, since aqueous solvents result in a satisfactory reaction between the halide mixture and hexamethylenetetramine;
This is also because water needs to be present in the reaction mixture so that the hydrolysis step can proceed without interruption.

Together with 3-phenoxybenzal halide, 3
- The reaction of phenoxybenzyl halide with hexamethylenetetramine and the simultaneous transformation of the products of this reaction proceed smoothly and efficiently when carried out in the presence of a non-acidic solvent. Good results have been obtained with alkanols having up to 4 carbon atoms per molecule, preferably from 40% to 80% by volume.
Alkanol containing 60% to 70% by volume/
This is accomplished using a mixture of water.

The reaction in step (a) of the process according to the invention is exothermic and generally no heating is required to initiate the reaction;
It is carried out at a temperature in the range of 150°C. The hydrolysis step may be carried out at temperatures ranging from 40 to 200°C, preferably at 50°C.
It can be carried out at temperatures ranging from 120°C to 120°C. Short reaction times, e.g. 2 to 8 hours,
It is sufficient if the reaction is carried out at a temperature of e.g. 100 to 200°C, and relatively long reaction times, e.g. 8 to 25 hours, are carried out at temperatures of e.g.
required at a temperature of The reaction can be carried out under automatic overpressure.

Instead of hexamethylenetetramine, ammonia and formaldehyde can be used in step (a) of the method of the invention and similar results are obtained due to the chemical equilibrium between hexamethylenetetramine and ammonia and formaldehyde. That is clear. Thus, ammonia and formaldehyde can be considered precursors to hexamethylenetetramine.

Although mixtures of benzyl and benzal halides may be obtained by any convenient means, it is believed that such mixtures may be readily prepared by halogenation of appropriate 3-phenoxytoluenes. I found out. For example, it can be halogenated with gaseous halogen or sulfuryl chloride at elevated temperatures in the presence of a free radical initiator. The temperature of the halogenation reaction is highly dependent on the nature of the halogen used and the need to avoid ring halogenation of the 3-phenoxytoluene. Typical temperature ranges for halogenation reactions are:
The temperature is between 50 and 250°C.

As far as the chlorination of 3-phenoxytoluene is concerned, better results are obtained by contacting 3-phenoxytoluene with gaseous chlorine or sulfuryl chloride in a non-polar solvent at temperatures ranging from 40 to 100°C. As a result, the free radical initiator is preferably a peroxide initiator or an azo initiator such as benzoyl peroxide or azoisobutyronitrile (AIBN). Generally speaking, halogenated hydrocarbons such as carbon tetrachloride and perchlorethylene are suitable solvents for this reaction. Excellent results were obtained using carbon tetrachloride as the solvent. Benzene is also a suitable solvent. To favor side chain chlorination of toluene and suppress ring chlorination, prevent chlorination of 3-phenoxytoluene that occurs at high concentrations, e.g., concentrations of 3-phenoxytoluene exceeding 60% by weight in the solvent. I found that this is preferable.
It has been found that concentrations of up to 50% by weight are generally preferred.

An important feature of the process of the invention is that a mixture of 3-phenoxybenzyl halide and 3-phenoxybenzyl halide in any proportion (i.e.
Mixtures of mono- and dihalides) are flexible and can be converted into the desired aldehydes.

When the undistilled 3-phenoxybenzaldehyde obtained according to the invention is used in the manner described above for the preparation of alpha-cyano-3-phenoxybenzyl esters, the esters can be prepared in high yields. and in the substantial absence of dicyano compounds of general formula Q.

Commercially useful esters, given their importance as pyrethroids, have the formula [In the formula, ^R2 is 1-(4-chlorophenyl)-2-methylpropyl group, 2,2,3,3-tetramethylcyclopropyl group, 2-(2,2-dichlorovinyl)-3,3- dimethylcyclopropyl group or 2
-(2,2-dibromovinyl)-3,3-dimethylcyclopropyl group]. The acyl halides from which these esters are derived may exist as a single stereoisomer or as a mixture of one or more of these stereoisomers. Therefore, the present invention
In the preparation of esters of pyrethroids by combining 3-phenoxybenzaldehyde with an acid chloride of a pyrethroid, e.g. a compound of the formula R ² -CO-halide, in the presence of cyanide ions, the method according to the invention 3-phenoxybenzaldehyde.

The invention is further illustrated by the following examples. Yields and purities shown below were determined by gas-liquid chromatography. The yield of 3-phenoxybenzaldehyde is calculated based on the total amount of starting 3-phenoxybenzyl chloride and 3-phenoxybenzyl chloride and is calculated based on the total amount of starting 3-phenoxybenzyl chloride and 3-phenoxybenzaldehyde and alpha-cyano-3-phenoxybenzyl 2-( 2,2-dichlorovinyl)-3,3-dimethylcyclopropanecarboxylate (hereinafter referred to as "pyrethroid compound A") and formula Q (where R ¹ is 2-(2,2-dichlorovinyl) )-3,3-dimethylcyclopropyl group) The yield of the dicyano compound (hereinafter referred to as "Compound B") was calculated based on the starting 3-phenoxybenzaldehyde.

The mixture of 3-phenoxybenzyl chloride and 3-phenoxybenzyl chloride used in the examples and comparative experiments was produced by the following typical operation.

Gaseous chlorine (1.1 mol, 39 g) was added to a solution of 3-phenoxytoluene (0.70 mol) and azoisobutyronitrile (5% m based on 3-phenoxytoluene) in carbon tetrachloride (700 ml). The solution was allowed to pass for 4 hours; the solution was kept under reflux (78°C). At the end of this period, the conversion of 3-phenoxytoluene was 99%. Evaporation of the solvent from the reaction mixture left a residue containing 3-phenoxybenzyl chloride and 3-phenoxydinazal chloride in an overall yield of 97% calculated based on the starting 3-phenoxytoluene. I remained there.

Example 3 using cyclohexane as the hydrocarbon solvent
- Preparation of phenoxybenzaldehyde hexamethylenetetramine (1 mol, 140 g),
60%w/40%w ethanol/water mixture (1300
ml) and a mixture of 3-phenoxybenzyl chloride (0.6 mol, 131 g) and 3-phenoxybenzyl chloride (0.43 mol, 109 g) was heated in a glass autoclave with a stirrer to 105 ml in 1 hour. ℃ (3 bar pressure). After stirring at this temperature for 5 hours, add 80% ethanol.
Distillation at atmospheric pressure as a mixture of %v/20%v ethanol/water (bottom temperature 78-104°C) yielded a residue, which was then divided into two equal parts and these parts were described below. They will be described as "part a" and "part b." Part a was dissolved in cyclohexane (211 ml, i.e. 1 of the starting 3-phenoxybenzyl chloride and 3-phenoxybenzyl chloride).
410 ml per mole) and the resulting cyclohexane phase was extracted with concentrated aqueous hydrochloric acid (36 wt%
HCl) twice, first with 140 ml and then with 80 ml, then with water (45 ml), with a 5% by weight aqueous solution of sodium bicarbonate (45 ml), then with water (45 ml).
Washed with. Thereafter, cyclohexane was removed by evaporation at a pressure lower than atmospheric pressure to obtain a residue containing 3-phenoxybenzaldehyde (yield 89%, purity 92%).

Example: Production of pyrethroid compound A. Equipped with a turbine stirrer (960 revolutions per minute, input 0.7 KW/m ³ ) and maintained at a temperature of 10°C.
In a 500 ml cylindrical reactor were added the example 3-phenoxybenzaldehyde (0.35 mol), 2-(2,2-dichlorovinyl)-3,3-dimethylcyclopropanecarbonyl chloride (0.37 mol) and xylene (300 ml). Loaded. A solution of sodium cyanide (0.42 mol) and tetra-n-butylammonium bromide (35 x 10 ^-6 mol) in water (103 g)
was gradually added to the reactor over a period of 3 hours. The mixture thus formed was stirred for 20 hours and then mixed with a 10% by weight aqueous solution of sodium carbonate (140 g) containing 5% by weight of sodium carbonate and 5% by weight of sodium chloride (140 g).
and with a 5% by weight aqueous solution of sodium chloride (140 g). Xylene was evaporated from the washed organic liquid at a final temperature of 90 °C and a pressure of 13 KPa to obtain a residue containing compound A (94% yield,
90% purity, no undesired dicyano compound B could be detected).

Comparative Experiment Preparation of 3-phenoxybenzaldehyde using toluene Part b of the example was extracted with toluene (211 ml) and the 3-phenoxybenzaldehyde was extracted with
The cyclohexane phase obtained from part a was isolated from the toluene extract phase as described in the example. 3-Phenoxybenzaldehyde was obtained in 89% yield and 89% purity.

Comparative Experiment Preparation of Compound A The 3-phenoxybenzaldehyde obtained in the comparative experiment was converted to Compound A in the manner of the example. At the end of 3 hours of stirring after all of the sodium cyanide solution has been added, 35% 3-phenoxybenzaldehyde and 2% 2-(2,2-dichlorovinyl)-3,3-dimethylcyclopropanecarbonyl Chloride was still present, indicating that the conversion of 3-phenoxybenzaldehyde to Compound A (37% at this point) could hardly be increased. Additionally, 10% of this carbonyl chloride was converted to dicyano compound B.

Example Preparation of 3-phenoxybenzaldehyde using cyclohexane Hexamethylenetetramine (1 mol, 140 g),
60%w/40%w ethanol/water mixture (917
ml) and a mixture of 3-phenoxybenzyl chloride (0.40 mol, 87.4 g) and 3-phenoxybenzyl chloride (0.29 mol, 73.4 g) in a glass autoclave equipped with a stirrer for 1 hour. and warmed to 105°C (3 bar pressure).
After stirring at this temperature for 5 hours, add ethanol.
Distilled as a mixture of 80% v/20% v ethanol/water at atmospheric pressure (bottom temperature 78-104 °C) to obtain a residue;
The residue is then divided into two equal parts, which parts are referred to below as "part a" and "part b". Part a was dissolved in cyclohexane (140 ml, i.e. 1 of the starting 3-phenoxybenzyl chloride and 3-phenoxybenzyl chloride).
410 ml per mole) and the resulting cyclohexane phase was extracted with concentrated aqueous hydrochloric acid (36% by weight)
HCl) twice, first with 40 ml and then with 25 ml, and with water (15 ml), with a 5% by weight aqueous solution of sodium bicarbonate (15 ml) and then with water (15 ml). Thereafter, cyclohexane was removed by evaporation at a pressure lower than atmospheric pressure to obtain a residue containing 3-phenoxybenzaldehyde (yield 89%, purity 92%).

Example Preparation of pyrethroid compound A The 3-phenoxybenzaldehyde obtained in the example was converted to compound A in the manner of the example. The yield of compound A was 94%, the purity was 90%, and the content of dicyano compound B was 0.4%.

Comparative Experiment Preparation of 3-phenoxybenzaldehyde using toluene Part b of the example was extracted with toluene (140 ml) and 3-phenoxybenzaldehyde was extracted with
The cyclohexane phase obtained from example a was isolated from the toluene extract phase as described in the example. 3-Phenoxybenzaldehyde was obtained with a yield of 89% and a purity of 89%.

Comparative Experiment Preparation of Pyrethroid Compound A The 3-phenoxybenzaldehyde obtained in the comparative experiment was converted to Compound A in the manner of the example. At the end of 3 hours of stirring after all of the sodium cyanide solution was added, the same results as in the comparative experiment were obtained.

Example Preparation of 3-phenoxybenzaldehyde using cyclohexane The example experiment was repeated, but instead of 140 ml
250 ml of cyclohexane are used for the extraction of part a, corresponding to 724 ml of cyclohexane per mole of starting 3-phenoxybenzyl chloride and 3-phenoxybenzyl chloride. Yield of 3-phenoxybenzaldehyde: 89
% and purity 92%.

Example Preparation of pyrethroid compound A 3-phenoxybenzaldehyde obtained in the example was converted to compound A in the manner of the example. Compound A
The yield was 94%, the purity was 90%, and the content of dicyano compound B was 0.4%.

Example Preparation of 3-phenoxybenzaldehyde using n-heptane Hexamethylenetetramine (1 mol, 140 g),
60%w/40%w ethanol/water mixture (917
ml) and a mixture of 3-phenoxybenzyl chloride (0.50 mol, 109 g) and 3-phenoxybenzyl chloride (0.43 mol, 109 g) was heated in a glass autoclave with a stirrer to 105 ml in 1 hour. ℃ (3 bar pressure). After stirring at this temperature for 5 hours, add 80% ethanol.
Distillation at atmospheric pressure as a mixture of %v/20%v ethanol/water (bottom temperature 78-104°C) yielded a residue, which was then divided into two equal parts and these parts were described below. They will be described as "part a" and "part b." Part a is n-heptane (215
ml of starting 3-phenoxybenzyl chloride and 430 ml per mole of 3-phenoxybenzyl chloride) and the resulting heptane phase was extracted with concentrated aqueous hydrochloric acid (36% by weight HCl). It was washed twice, first with 50 ml and then with 34 ml, and with water (25 ml), with a 5% by weight aqueous solution of sodium bicarbonate (25 ml) and then with water (25 ml). Thereafter, n-heptane was removed by evaporation at a pressure lower than atmospheric pressure to obtain a residue containing 3-phenoxybenzaldehyde (89% yield, 91% purity).

Example Preparation of pyrethroid compound A The 3-phenoxybenzaldehyde obtained in the example was converted to compound A in the manner of the example. The yield of compound A was 94%, the purity was 90%, and the content of dicyano compound B was 0.4%.

Comparative Experiment Preparation of 3-phenoxybenzaldehyde using toluene Part b of the example was extracted with toluene (215 ml) and 3-phenoxybenzaldehyde was extracted with
The heptane phase obtained from part a was isolated from the toluene extract phase as described in the example.
3-Phenoxybenzaldehyde was obtained with a yield of 89% and a purity of 89%.

Comparative Experiment Preparation of Pyrethroid Compound A The 3-phenoxybenzaldehyde obtained in the comparative experiment was converted to Compound A in the manner of the example. At the end of 3 hours of stirring after all of the sodium cyanide solution was added, the same results as in the comparative experiment were obtained.

EXAMPLE Preparation of 3-phenoxybenzaldehyde using a mixture of alkanes The experiment of the example was repeated using a mixture of alkanes having a boiling range of 107°C to 138°C. 3-
Phenoxybenzaldehyde was obtained in 89% yield and 91% purity.

Example Preparation of pyrethroid compound A 3-phenoxybenzaldehyde obtained in the example was converted to compound A in the manner of the example. Compound A
The yield was 94%, the purity was 90%, and the content of dicyano compound B was 0.4%.

Claims (1)

[Claims] 1. Steps: (a) treating a mixture of 3-phenoxybenzyl halide and 3-phenoxybenzyl halide in the presence of hexamethylenetetramine and a solvent, and the resulting product; (b) removing the solvent from the reaction mixture obtained in step (a); (c) one or more alkanes and/or one or more alkanes; Treating the residue of step (b) with a hydrocarbon solvent consisting essentially of more than 3-
A method for producing 3-phenoxybenzaldehyde, comprising the steps of: producing a hydrocarbon extract phase containing phenoxybenzaldehyde; and (d) washing the hydrocarbon extract phase with an aqueous solution of a strong acid. 2. A method according to claim 1, characterized in that the hydrocarbon solvent in step (c) is a solvent consisting essentially of one or more cycloalkanes. 3. The method according to claim 1 or 2, wherein the hydrocarbon solvent is cyclohexane. 4 In step (c), 300 to 1 mole of the mixture of benzyl halide and benzal halide
4. Process according to claim 1, characterized in that the hydrocarbon solvent is used in an amount in the range 1500 ml. 5. The method according to any one of claims 1 to 4, characterized in that the strong acid used in step (d) is hydrochloric acid. 6. Process according to claim 5, characterized in that in step (d) the aqueous solution contains at least 15% by weight of hydrogen chloride. 7. Process according to claim 6, characterized in that the solvent used in step (a) comprises an alkanol having up to 4 carbon atoms per molecule. 8. The method according to claim 7, characterized in that the alkanol is ethanol. 9. Claim 9, characterized in that the solvent used in step (a) is an alkanol-water mixture containing from 40% to 80% by volume of alkanols having up to 4 carbon atoms per molecule. The method described in item 7 or 8.