CS196211B2 - Process for preparing phenoxybenzylalcohols - Google Patents

Description

The present invention relates to a process for the preparation of novel phenoxybenzyl alcohols useful as intermediates for the preparation of novel substituted phenoxybenzyloxycarbonyl derivatives having insecticidal and acaricidal activity.

New substituted phenoxybenzyl alcohols corresponding to formula I

in which

R ¹ and R ¹ are different from each other and are hydrogen, fluorine or bromine.

The phenoxybenzyl alcohols of formula (I) according to the present invention are prepared by producing phenoxybenzaldehydes of formula (I). II in which

R and R ¹ have the abovementioned meaning, are reacted with alkali cyanide, * metal, e.g., sodium cyanide or potassium cyanide, in the presence of acid, optionally with the addition of a solvent.

If, for example, 3- (2-fluorophenoxy) benzaldehyde and potassium cyanide are used as starting materials in the process according to the invention, the reaction scheme can be illustrated as follows:

CH 2 CO-OH 4

-C ^ COOK *

The starting materials used are unambiguously defined by formula II. In this formula, the general symbols have the following preferred meanings:

196211 3

R is fluorine or bromine,

R ¹ represents hydrogen or fluorine ·.

Alkali metal cyanides are described in the literature.

The phenoxybenzaldehydes of formula (II) can be prepared by generally conventional processes, for example by reacting the corresponding phenoxybenzyl halides of Formula IV, which are prepared by conventional methods from the corresponding denoxytoluenes, with hexamethylenetetraminein according to the following reaction scheme:

(II) where. '

R and R ¹ have the abovementioned meaning and

Hal is halogen. -...........

Examples of phenoxybenzaldehydes used in the reaction according to the invention are:

3- (4-fluorophenoxy) benzaldehyde,

3- (3-fluorophenoxy) benzaldehyde,

3- (2-fluorophenoxy) benzaldehyde,

3- (4-bromophenoxy) benzaldehyde,

3- (3-bromophenoxy) benzaldehyde,

3- (2-bromophenoxy) benzaldehyde,

3-Phenoxy-6-fluorobenzaldehyde.

The process for the preparation of the compounds of the invention is preferably carried out using suitable solvents and diluents.

Suitable solvents are preferably water, alcohols such as methanol, ethanol or ethers such as diethyl ether, or nitriles such as acetonitrile.

Acids which can be used in the process according to the invention are inorganic acids such as hydrochloric acid or sulfuric acid, or organic acids such as acetic acid or formic acid.

The reaction temperature can be varied within a wide range. Generally the reaction is carried out at temperatures from -10 to 110 ° C, preferably at -5-to ^20? C.

The reaction is usually avoided under atmospheric conditions. pressure.

The reaction is carried out using cyanide at 100 to 100

150% and surplus. The reaction is preferably carried out in one of the above-mentioned solvents or diluents at the indicated mixing temperatures. After a reaction time of one to several hours, usually at elevated temperature, the reaction mixture is worked up by generally conventional methods.

The novel compounds are obtained in the form of oils which can either be distilled or, by so-called "distillation", i.e., longer heating under reduced pressure and slightly elevated temperatures, free of the last volatiles "and thus purified. refractive index or boiling temperature.

Examples of novel phenoxybenzyl alcohols which are useful in the production of phenoxybenzyloxycarbonyl derivatives are:

3- (4-fluorophenoxy) -α-cyanobenzyl alcohol,

3- (3-fluorophenoxy) -α-cyanobenzyl alcohol,

3- (4-bromophenoxy) -α-cyanobenzyl alcohol.

3- (3-bromophenoxy) -α-cyanobenzyl alcohol,

3- (2-fluorophenoxy) -α-cyanobenzyl alcohol,

3- (2-bromophenoxy) -α-cyanobenzyl alcohol.

Phenoxybenzyl alcohols can be prepared by the following procedures.

Example 1

g (0445 mol) of 3- (3-fluorophenoxy) toluene are dissolved in 300 ml of anhydrous tetrachloride.

The methane and the solution is heated ,, et al, _us79? 3 g of N-bromosuccinimide to _V under reflux. After reaching a temperature of 70 ° C, 5 g of azodiisobutyric acid nitrile is added, after about 10 to 20 minutes the reaction develops under heat and, after the exothermic reaction has subsided, the reaction mixture is refluxed for 4 hours. The reaction mixture is then cooled to 10 ° C, the succinimide is filtered off and the carbon tetrachloride is distilled off in vacuo. · The residual oil, distilling at _t te fence 143 to 150 ° C / 133 mbar. 72.9 g (58.2% of theory) of 3- (3-fluorophenoxy) benzyl bromide are obtained.

The following compounds can be prepared in an analogous manner:

Boiling point: 145-150 ° C / 133 Pa Yield: 61%

Cni-Br boiling point: 160 to 165 ^o C / 400 Pa yield: '54; 5 ^: % * theory 'Example 2 ⁴⁸

g (0.17 mol) of 3- (3-fluorophenoxy) benzyl bromide and 47.8 g of hexamethylenetetramine in 250 ml of methylene chloride are heated at reflux for 3 hours, then the mixture is cooled to 5-10 ° C and the precipitate formed is filtered off. The precipitate was washed with 100 ml of methylene chloride, dried by filtration and then heated to reflux in 100 ml of 50% aqueous acetic acid for 5 hours. Then 25 ml of concentrated hydrochloric acid are added,

B mixture. The mixture was heated to reflux for 30 minutes and then cooled to 10-20 ° C. 200 ml of water are added to the reaction mixture and extraction is carried out twice with 150 ml of ether each time, and the combined ether phases are then washed with sodium bicarbonate solution and dried over sodium sulphate. The ether was distilled off in vacuo. Yield: 3- (3-fluorophenoxy) benzaldehyde, b.p. 142-148 ° C / 1 mmHg, in 31% yield.

The following compounds can be prepared in an analogous manner.

CHO melting point: 48 DEG C. yield; j © 2 '%: theory

refractive index: n _D ^22; 1.6109 yield: 67% of theory

Example 3

AND

CH-OH

21.6 g (0.1 mol) of 3- (4-fluorophenoxy) benzaldehyde are dissolved in 25 ml of glacial acetic acid, and 10.2 g of sodium cyanide dissolved in 25 ml of water are added dropwise at 5 DEG C. with stirring. After stirring at 20 ° C for 8 hours, the reaction mixture is poured into 100 ml of water, extracted with 200 ml of ether, and the ether phase is separated. After distilling off the ether in vacuo, 17 g (70% of theory) of 3- (4-fluorophenoxy) -α-cyanobenzylalcohol with a refractive index n _{D of} ²³ : 1.5643 are obtained.

The following compounds can be prepared in an analogous manner:

⁸ refractive index n _D ²² = 1.5700 yield: 69% of theory

yield: 93% of theory

refractive index n _D ²² yield: 88% of theory

Claims (1)

A process for the preparation of phenoxybenzyl alcohols of the general formula I CN 'in which R ¹ and R ¹ are different from each other and are hydrogen, fluoro or bromo, YNALEZU characterized in that the phenoxybenzaldehydes of the general formula II in which: R and R ¹ have the abovementioned meanings, are reacted with alkali metal cyanide, for example sodium cyanide or potassium cyanide, in the presence of acid and optionally with the addition of a solvent. imroirafla, n. p. 7, Mom.