CA1269674A - Process for preparation of 3-phenoxybenzyl 2-(4- alkoxyphenyl)-2-methylpropyl ethers - Google Patents

Abstract

Abstract of the Disclosure Disclosed is a process for preparing 3-phenoxybenzyl 2-(4-alkoxyphenyl)-2-methylpropyl ethers represented by the following formula (I):

(I) wherein R stands for a lower alkyl group, and X1 and X2 stand for a hydrogen atom or fluorine atom, which comprises subjecting a 3-phenoxybenzyl 2-(4-alkoxy-3-halogenophenyl)-2-methylpropyl ether or 3-phenoxybenzyl -2-(4-alkoxy-3,5-dihalogenophenyl)-2-methylpropyl ether represented by the following formula (II):

(II) wherein R stands for a lower alkyl group, X1 and X2 stand for a hydrogen atom or fluorine atom, and Y1 and Y2 stand for a hydrogen atom, chlorine atom, bromine atom or iodine atom, with the proviso that at least one of Y1 and Y2 is a chlorine atom, bromine atom or iodine atom, to dechlorination, debromination or deiodination by hydrogenation, wherein the dechlorination, debromi-nation or deiodination is carried out in the presence of a hydrogenation catalyst by using as a hydrogenative reducing agent a lower aliphatic alcohol and an alkali compound selected from the group comprising alkali metal hydroxides and alkaline earth metal hydroxides.
According to this process, compounds of the formula (I) can be obtained in high yields with safety without using hydrogen.

Description

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Field of Industrial Application The present invention relates to a process for the preparation of 3-phenoxybenzyl 2-~4-alkoxyphenyl)-2-methyl-propyl ethers represented by the following ~ormula (I)~

CH3 /--~,<
RO~ CHz OCHz--@< g2 ( I ) CH3 ~L

S wherein R stands for a lower alkyl group, and X1 and X2 stand for a hydrogen atom or fluorine atom.
A 3-phenoxybenzyl ether type derivative represented by the formula (I) is an excellent pest-controlling agent having very high insecticidal and acaricidal activities, being excellent in the immediate effect and residual effect of being less koxic to not only men and domestic animals but als:o fish.
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prior Art A process for the preparation of a compound of ~he formula (I) having an alkoxy group on the benzene nucleus of the neophyl group is disclosed in Japanese Pate.nt 5 Application Laid-Open Specification No. 1~4427/81, and it is taught that the neophyl derivative can be prepared by condensing a compound represented by the following formula (III):

~ - ¢ -C H~O H (m) R O C Hl with a 3-phenoxybenzyl halide or alcohol or by condensing a compound represented by the following formula (IV):

~ C H2g t~) .
wherein X stands for a halogen atom, with a 3-phenoxybenzyl alcohol~
The reaction path for the synthesis of the compound of the formula (III) is long, and the process for preparing the compound of the formula (I) from the compound of the formula ~ as the starting material is disadvantageous from the industrial viewpoint.
As the process for preparing the compound of the ; formula (IY), for example, the above-mentioned laid-open specification discloses a process represented by the following reaction formulas:

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7~k (1) CH3 sul rurylC Hl chloride ~ ~--¢--CH2C Q

RO CH, RO C}I3

(2) C~:-2 CX3 ~ + C ~ C ~,2 C Q e ~>--C--C ~I. Ç Q
RO CH~ RO CH3 However, in the case where the 4-position is substituted with a lower alkoxy group, acco~ding to the process of the reaction for~ula (1), a nuclear chlorina~ion reaction is preferentially advanced, and the intended 4-alko~yneophyl chloride is in only a very poor yield obtained. Further-more, according to ~he proces~ o~ the react~on ~orm~la (2), an alXylation re~c~ion ~t the ortho-posi~ion to the ~lkoxy group is pr~erentlally advanced and a large quan-tity cf an oratho-~so~er is ~ormed as a by-product, and since effective separation of the i~omers is difficult, the intended 4-alkoxyn~ophyl chloride having a high purity can be obtained only in a very low yield.
Moreover, the obtained 4-alkoxyneophyl chloride is `.
an unstable compound, and storage and han~ling thereof on an industrial scale involve various difficulties.
As the improved process for overcoming the foregoing disadvantages, Japanese Patent Application Laid-Open Specification No. 73535/84 proposes a process in which a 4-alkoxyhalogenoneophyl halide having at leas~ one chlorine or bromine atom substitu~ed at the ortho-position to the alkoxy group is used and ~his compound is reaated with a

3-phenoxybenzyl alcohol to obtain a compound of the formula (II) and a compound of ~he formula (I) is obtained from this compound of the formula tII).
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Y~, C~ ~o-~
R ( ) ~ <~--C--C H2 O C H~ z Yl CH, ~:1 wherein R stands for a lower alkyl group, X1 and X2 stand for a hydrogen atom or ~luorine atom, and Y1 and Y2 stand for a hydrogen atom, chlorine atom or bromine atom, wi~h the proviso that at least one of Y1 and Y2 is a chlorin~
atom or bromine atom.

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In this laid-opPn speci~ication, it is taught that the compound of the ~ormula (I) is obtained by subjecting the compound of the formula (II~ to catalytic hydrodehalo-genation using hydrogen in a solvent such as methanol in the presence of a hydrogenation catalyst ~uch as palladium and a base as the dehydrohalogenating agent.
The fatal defect of this process i8 that hydrogen gas is used at the dehalogenating step. Namely, in the case where this process is worked on an industrial scale, special care should be taken to maintain safety and the location is limited because hydrogen gas-supplying equip-ment is necessary. Moreover, large equipment expenses are necessary and hence the process is disadvantageous also from the economical viewpoint.
In the catalytic hydrogenation reaction using hydrogen, cleaving is readily cau~ed in a compound having an 0 benzyl group and a fluorine atom, such as the compound of the ~ormula (II), unless the hydrogenation conditions are strictly controlled. It has been found that this tendency is especially prominent when a palladium type catalyst, which i~ know~ to be preferred as a dehalogen-ation catalyst, is used.
As the process not using hydrogen, there may be considered a process in which a known reducing agent such as sodium formate is used. However, it has been found that even if the compound of the formula (II) used in the present invention is reacted with sodium formate as the reducing agent, the unreacted substance and the by-product formed by cleaving of the ether linkage are contained in large quantities in the dehalogenation reaction liquid.
Means for Solvinq the Problems We made research on the process for obtaining the compound of the formula (I) by removing chlorine, bromine , . . : .
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or iodine from the compound of the formula (II) by hydro-dehalogenation reaction, and as the result, it was found that if an alkali compound and an alcohol are present in amounts larger than the stoichiometrically necessary amounts in the presence of a hydrogenation catalyst, hydrogen gas need not indispensably be added to the re~
action and the reaction can be advanced only by hydrogen generated from the alkali and alcohol, and to our great surprise it also was found that the dechlorination or debromination reaction can be carried out in a yield comparable to or higher than the yield attained in thP
process using hydrogen gas supplied from outside of the reaction system, disslosed in the above-mentioned laid-open specification. We have now completed the present invention based on these findings.
Since hydrogen gas supplied from outside of the reaction system is not used, the process of the present invention is much safer and is advantageous from the eco-nomical viewpoi~t over the process using hydrogen gas supplied from outside of the reaction system. By dint of this advantage and high functional utili~y of compounds prepared according to the process of ~he present invention, the process of the present invention has a very high industrial value.
In the hydrodehalogenative reduction reaction of the present invention, in order to obtain the intended compound of the formula (1) in a high yield without using hydrogen gas supplied from outside of the reaction system, an alkali metal or alkaline earth metal hydroxide and a lower ali-phatic alcohol should be used in combination besides a hydrogenation catalyst and a customarily used dehydrohalo~
genating agent as a base. The reason is presumed to be as follows:
For example, when sodium hydroxide is used as the alkall metal hydroxide and methanol is used as the lower ..
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aliphatic alcohol, sodium hydroxide i5 reacted with methanol in ~he presence o~ a hydrogenation ca~alyst to form formic acid and this formic acid is decomposed to sodium formate and finally to sodium carbonate. At this time, stoichiometrically speaking, by using 2 moles of sodium hydroxide per mole of methanol, 3 moles of hydrogen is finally formed, and this hydrogen acts efficiently on the dehalogenation reaction of the compound of the formula ~II) under the influence of the catalyst.
lo Accordingly, in the process of the present inven-tion, an alkali compound for generating hydrogen should be present in addition to a base acting as the dehalogenating agent. As the alkali compound, there can be mentioned, for example, sodium hydroxide, potassium hydroxide and calcium hydroxide.
The ~lkali compound may be u~ed singly in a large amount so that it also acts as the neutralizing agent for the formed hydrohalogenic acid, but, of course, a different base may be used as the dehydrohalogenating agent in combination with the alkali compound.
As the base that can be used as the dehydro-halogenating agent in combination with the alkali compound, there can be mentioned inorganic and oryanic bases such as potassium carbonate, sodium carbonate and sodium acetate, and aliphatic, aromatic and hsterocyclic amines such as triethylamine, ethylenediamine, diethylaniline and py-ridine. Single use of an inorganic base is preferred, and single use af an alkali metal hydroxide, particularly sodium hydraxide, is especially advantageous from the economical viewpoint.
In the present invention, when the alkali metal hydroxide alone is used, hydrogen is generated by reacting the alkali in an amount of at least two moles with the !

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stoichiometric amou~t of methanol, and consequently, in order to give the dehalogenated product, the alkali should be used in an amoun~ of at least 0.~6 mole per mole of the starting c~mpound of the formula ~II), ~or example, a 3-phenoxybenzyl 2~(4-alkoxy-3-halogenoph~nyl)-2 mPthylpropyl ether.
When the action of the alkali as the dehydro-halogenating agent is also intended, it is preferred that the alkali be used in an amount of 1.0 to 10 moles per lo mole of the compound of the formula (II), for example, a 3-phenoxybenzyl 2-(4-alkoxy-3-halogenophenyl~-2-methyl-propyl ether.
Therefore, the amount of the alkali is preferably 1.66 to 10.7 moles per halogen atom at Yl and Y2 in the compound of the formula (II) in a~l, gi~en by summing up "at least 0.66 mole for hydrogen formation for dehalogenat-ing agent" and "at least 1 mole as dehydroh~logenating agent (neutralizing agent for the formed hydrohalogenic acid)".
As the alcohol used as the reducing ag~nt in com-bination with the alkali in the process of the present invention, there can be mentioned lowsr aliphatic monools and diols such as methanol, ethanol, isopropanol, n-pro-panol, n-butanol, isobutanol, ethylene glycol and propylene glycol. Monools, especially methanol, are preferred.
These alcohols may be used in the form of mixtures of two or more of them. When an alkali metal hydroxide is used as the alkali and a monool is used as the alcohol, it is necessary that the alcohol should be used in an amount of at least about 0.3 mole of the stoichiometric amount, preferably 0.4 to 30 moles, per mole of the compound of the formula (II), for example, a 3-phenoxybenzyl 2-(4-alkoxy-3-halogenophenyl)-2-methylpropyl ether, and when the alcohol is used also as the reaction medium described ;, 35 below, the amount of alcohol is appropriately selected .

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while taking the amount of the alcohol used as the reaction medium into consideration.
In the hydrodehalogenation step, addition of water is not ab~olutely n~cessary. Howev~r, in order to increase 5 the reaction rate, it is prePerred that water be added and the reaction be carried out in a water-containing organic solvent. Various organic solvents, for example, alcohols such as methanol, polyhydric alcohols such as ethylene glycol, acetic acid and acetic acid esters may be used as the organic solvent. However, it is preferred that the same alcohol as used in the reducing reaction be used.
When the organic solvent is used, it is preferred that the concentration be adjusted to 20 to 80%. When an alcohol and water are used as the reaction medium, the concentra-tion of the alcohol is selected within the above-mentioned range while taking the amount of the alcohol used in the reducing reaction into consideration.
The amount o~ the reaction medium used can be selected within a broad range, but in view of the reaction rate and the volume efficiency of the reaction vessel, it is preferred that the reaction medium be used in an amount of 2 to 10 parts by volume per part by volume of the compound of the formula (II).
As the catalyst, there can be used a nickel catalyst such as Raney nickel, a palladium catalyst such as pal-ladium-carbon or palladium-alumina, and a platinum cata-lyst. Palladium-carbon is especially advantageous. The catalyst is used in an amount of 0.1 to 20% by weight, preferably 1 to 6% by weight, based on the compound repre-sented by the formula (II).
As the 4-alkoxyneophyl ether derivative o the formula (I) prepared according to the process oP the present invention, there can be mentioned 3-phenoxybenzyl 2-(4-methoxyphenyl)-2-methylpropyl ether, 3 phenoxy-4-., . . . .

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fluorobenzyl 2-(4-methoxyphenyl)~2-methylpropyl ether, 3-~4-fluorophenoxy)benzyl 2-~4-methoxyphenyl)-2-methylpropyl ether, 3-(4-fluorophenoxy)-4-fluoroben2yl 2-(4-methoxy-phenyl)-2-methylpropyl ether, 3-phenoxybenzyl 2 (4-ethoxy-phenyl)-2-methylpropyl ether, 3-phenoxy-4-~luorobenzyl 2-(4-ethoxyphenyl)-2-methylpropyl ether, 3-(4-fluorophenoxy) benzyl 2-(4-ethoxyphenyl)-2-methylpropyl ether, 3-(4-fluorophenoxy)-4-fluorobenzyl 2-(4-ethoxyphenyl)-2-methyl-propyl ether, 3-phenoxy-6-fluorobenzyl 2-(~-ethoxyphenyl)-2-methylpropyl ether, 3-(2-fluorophenoxy)benzyl 2-(4-ethoxyphenyl)-2-methylpropyl ether, 3-phenoxybenzyl 2-(4-(i-propoxy)phenyl)-2-methylpropyl ether, 3-phenoxy-4-fluorobenzyl 2-(4-(i-propoxy ? phenyl)-2-methylpropyl ether, 3-phenoxybenzyl 2-(4-(1-methylpropoxy)phenyl)-2-methyl-propyl ether, 3-phenoxybenzyl 2-(4-(n-butoxy)phenyl)-2-methylpropyl ether, 3-phenoxybenzyl 2-(4-(t-butoxy)phenyl)-2-methylpropyl ether and 3-phenoxybenzyl 2-(4-(n-penty-loxy)-phenyl)-~-methylpropyl ether.
A general ~mbodiment of the present invention will now be described. The dehalogenation reaction of the present invention may be carried out under atmospheric pressure according to the amounts of the hydrogenation catalyst, the alkali compound and the lower alcohol used.
However, it is generally preferred that the reaction be carried out under an elevated pressure.
A reaction vessel is charged with predetermined amounts of a 3-phenoxybenzyl 2-(4-alkoxy-3-halogenophenyl)-2-methylpropyl ether or 3-phenoxybenzyl 2-(4-alkoxy-3,5-dihalogenophenyl)-2-methylpropyl ether represented by the general formula (II), an alcohol and alkali as the reducing agent and a hydrogenation catalyst, and the mixture is heated at 50 to 220C, preferably 80 to 150C, and stirred at this temperature for 0.5 to 50 hours, preferably 3 to 30 hours. The reaction mixture is cooled to room tempera-ture, and if necessary, in order to form a homogeneoussolution, a nonpolar solvent such as water or benzene is ,~.
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added, and the catalyst is separated by filtration under reduced pressure. The mother liquor is subjected to phase separation, and the oil layer is washed with water and dehydrated and the solvent is removed to give a 3-pheno~y-benzyl 2-(4-alkoxyphenyl)-2-methylpropyl ether represented by the general fo~nula (I) as the intended product.
The obtained product can be satisfactorily used as such as an insecticidal and acaricidal agent, but according to need, the product may be purified by reduced pressure distillation, column chromatography or recrystalliæation.
The present invention will now be described in detail more with reference to the following examples.
Example 1 An autoclave having a capacity of 500 m~ was charged with 60.0 g (0.146 mole) of 3-phenoxybenzyl 2-(3-chloro-4-ethoxyphenyl)-2-methylpropyl ether, 18.8g (0.47 mole~ of flaky sodium hdyroxide, 2.4 g of 5%-palladium-carbon (50%
wet), 85.3 g (2~66 moles) of methanol and 36 g of water.
The autoclave was sealed and the inner atmosphere was replaced by nitrogen, and the mixture was heated with stirring at an inner temperature of 1~0C for 12 hours to complete reaction.
The reaction was cooled to 50C and the residual pressure as released, and 100 m~ of benzene was added into the autoclave to dissolve the oil layer. Then, the cata-lyst was removed by filtration, and the filtrate was allowed to stand still to cause phase separation, and the benzene layer was recovered and washed with 120 m~ of water three times, and benzene was removed by distillation under reduced pressure to give an oily product. From the results of the analysis of the oily product by gas chroma-tography according to the internal standard method, it was found that the oily product comprised 98.8~ of 3-phenoxybenæyl 2-(4-ethoxyphenyl)-2-methylpropyl ether and ~, `. - ' ' ' ' : .

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0.3~ of unreac~ed starting 3-phenoxybenzyl 2-(3-chloro-4-ethoxyphenyl)-2-methylpropyl ether, and that the content of aach of 3-phenoxytoluene and 4-ethoxyneophyl alcohol formed by cleaving of the ether linkage was lower than 0.3%. The amount of the obtained oil product was 53.8 g, and the yield was 96.7%.
Example 2 An autoclave having a capacity of 300 m~ was charged with 60.0 g (0.140 mole) of 3-phenoxy-4-*luorobenzyl 2-(3-lo chloro-4-ethoxyphenyl)-2-methylpropyl ether, 18.8 g (0.47 mole) of flaXy sodium hydroxide, 2.4 g of 5~-palladium carbon (50% wet), 56.9 g (1.77 moles) of methanol and 54.0 g of water~ The autoclave was sealed and the inner atmosphere was replaced by nitrogen, and the mixutre was heated with stirring at an inner temperature of 120C for 10 hours to complete reaction.
The reaction mixture was cooled to room temperature and the residual pressure was released, and 100 m~ of benzene was added into the autoclave to dissolve the oily portion. Then, the catalyst was removed by filtration, and the filtrate was sufficiently shaken and allowed to stand still to cause phase separation. Then, the obtained benzene la~er was washed with 100 m~ of water three times and benzene was removed by distillation under reduced pressure to give an oily product. From the results of the analysis of the oily product by gas chromatography accord-ing to the internal standard method, it was found that the oily product comprises 98.2% of 3-phenoxy-4-fluorobenzyl 2-(4-ethoxyphenyl)-2-methylpropyl ether and 0.7% of start-ing 3 phenoxy-4-fluorobenzyl 2-(3-chloro-4-ethoxyphenyl)-2-methylpropyl ether, and that the content of each of 3-phenoxy-4-fluorotoluene and 4-ethoxyneophyl alcohol formed by cleaving of the ether linkage was lower than 0.2%.
Moreover, 0.8% of 3-phenoxybenzyl 2-(4-ethoxyphenyl)-2-methylpropyl ether presumed to have been formed by reduc-tion of the fluorine atom was contained.
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The amount of the obtained oily product was 54.0 g and the yield was 96.0%.
Example 3 A four-necked glass ~lask having a capacity of 300 m~ was charged with 60.0 g (0.146 mole) of 3-phenoxybenzyl 2-(3-chloro-4-ethoxyphenyl)-2-methylpropyl ether, 18.8 g (0.47 mole) of flaky sodium hydroxide, 4.8 g of 5%-pal-ladium-carbon (50~ wet), 86.2 g (1.87 moles) of ethanol and 36 g of water, and the mixture was heated with stirring at the boiling point (81C) for 6 hours to complete reac-tion.
The reaction mixture was cooled to 50C, and 50 m~
of benzene was added into the reaction vessel to dissolve the oily portion. The catalyst was removed by filtration and the *iltrate was allowed to stand still to cause phase separation. The benzene layer was recovered and washed with 100 m~ of water three times. Benzene was removed by distilla~ionn under reduced pressure to give an oil pro-duct.
From the results of the analysis of the oily productby gas chromatography according to the internal standard method, it was found that the oily product comprises 96.2%
of 3-phenoxybenzyl 2-(4-ethoxyphenyl)-2-methylpropyl ether and 1.5% of unreacted starting 3-phenoxybenzyl 2-(3-chloro-

4-ethoxyphenyl)-2-methylpropyl ether, and that the oily product contained 0~5% of 3-phenoxytoluene and 0.2% of 4-ethoxyneophyl alcohol, each being formed by cleaving of the ether linkage. The amount of the obtained oily product was 54.0 g and the yield was 94.5~.
Example 4 A four-necked glass flask having a capacity of 300 m~ was charged with 60.0 g (0.146 mole) of 3-phenoxy-benzyl 2 (3-chloro-4-ethoxyphenyl)-2-methylpropyl ether, : .
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23.5 g (0.588 mole) of flaky sodium hydroxide, 4.8 g of

5%-palladium-carbon (50% wet), 18 g (0.290 mole) of ethy-lene glycol and 144 g of w~ter, and the mixture was heated with stirring at the boiliny point (104C) for 12 hours to complete reaction.
The reaction mixture was cooled to 50C and 50 m of benzene was added into the reaction vessel to dissolve the oily portion. The catalyst was removed by filtration and the filtrate was allowed to stand still to cause phase separation. The benzene layer was washed with 100 m~ of water three times. Benzene was removed by distillation under reduced pressure to give an oily product.
From the results of the analysis of the oily product by gas chromatography according to the internal standard method, it was found that the oily product comprised 95.3~
of 3-phenoxybenzyl 2~ ethoxyphenyl~-2-methylpropyl ether and 2.2% of unreacted starting 3-phenoxybenzyl 2-(3-chloro-4-ethoxyphanyl)-2-methy~propyl ether, and that the oily product contained 0.6% of 3-phenoxytoluene and 0.4% of 4-ethoxyneophyl alcohol, each being formed by cleaving ofthe ether linkage. The amount of the obtained oily product was 54.3 g and the yield was 94.1%.
Referential~Exa~ple An autoclave having a capacity of 500 m~ was charged with 60.0 g (0.146 mole) of 3-phenoxybenzyl 2-(3-chloro-4-ethoxyphenyl)-2-methylpropyl ether, 7.5 g (0.188 mole) of flaky sodium hydroxide, 7.2 g of 5~-palladium-carbon (50%
wet), 83.5 g of methanol and 36 m~ of water, and the autoclave was sealed and the inner atmosphere was replaced by nitrogen. Hydrogen was filled in the autoclave so that the pressure was 8 kg/cm2G. The mixture was heated with stirring at an inner temperature of 110C for 12 hours while supplying hydrogen so that the pressure was 8 to 10 kg~cm2G, to complete reaction.

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The reaction mixture was cooled to room temperature and the residual pressure was released, and 120 m~ of benzene was added into the autoclave to dissolve the oily layer. Then, the insoluble substance was removed by filtration, and the mother liquid was washe~ with 30 mC of benzene, sufficiently shaken and allowed to stand still to cause phase separation and give a benzene layer. The benzene layer was washed with 120 m of water three times and benzene was removed by distillation under pressure to give an oily product. From the results of the analysis of the oily product by gas chromatography according to the internal standard method, it was found that the oily product comprised 98.5% of 3-phenoxybenzyl 2-(4-ethoxy-phenyl~-2-methylpropyl ether and 0.5% of unreacted starting 3-phenoxybenzyl 2-(3-chloro-4-ethoxyphenyl)-2-methylpropyl ether, and that the content of each of 3-phenoxytoluene and 4-ethoxyneophyl alcohol formed by cleaving of the ether linkage was lower than 0.3%. The amount of the obtained oily product was 53.6 g and the yield was 96.0%.
Example 5 An autoclave having a capacity of 300 m~ was charged with 30.0 g (0.066 mole) of 3-phenoxybenzyl 2-(3-bromo-4-ethoxyphenyl)-2-methylpropyl ether, 8.5 g of flaky sodium hydroxide, 0.9 g of 5%-palladium-carbon (50% wet), 42.7 g (2.3 moles) of methanol and 18 g of water, and the autoc-lave was sealed and the inner atmosphere was replaced by nitrogen. The mixture was heated with stirring at an inner temperature of 110C for 10 hours to complete reac-tion.
The xeaction mixture was cooled to 50C and the residual pressure was released, and 70 m~ of benzene was added into the autoclave to dissolve the oil layer. The catalyst was removed by filtration, and the filtrate was allowed to stand still to cause phase separation to give a ~ 35 benzene layer. Then, the benzene layer was washed with y~ lO0 m~ of water three times, and benzene was removed by -, -. . : . ............ . .
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distillation under reduced pressure to yive an oily pro-duct. ~rom the results of the analysis of the oily product by gas chromatography according to the internal standard method, it was found that the oily product comprised 98.6%
of 3-phenoxybenzyl 2-(4-ethoxyphenyl~-2-methylpropyl ether and 0.~% of unreacted ~tarting 3-phenoxybenzyl 2-~3-bromo-4-ethoxyphenyl)-2-methylpropyl ether, and that the content of each of 3-phenoxytoluene and 4-ethoxyneophyl alcohol formed by cleaving of the ether linkage was lower than 0.3%. The amount of the obtained oily product was 23.8 g and the yield was 94.4%.
Example 6 An autoclave having a capacity of 300 m~ was charged with 40.0 g (0.072 mole) of 3-phenoxybenzyl 2-(3-iodo-4-ethoxyphenyl)-2-methylpropyl ether, 9.3 g (0.23 mole) of flaky sodium hydroxide, 1~2 g of 5%-palladium carbon (50 wet), 64.0 g (2.0 moles) of methanol and 27 g of water, and the autoclave was sealed and the inner atmosphere was replaced by nitrogen. The mixture was heated with stirring at ~n inner temperature of 110C ~or 10 hours to complete reaction.
An oily product was obtained by carrying out the post-treatment in the same manner as in Example 5. From the results of the analysis of the oily product by gas chromatography according to the internal standard method, it was found that the oily product comprises 99.2% of 3-phenoxybenzyl 2-(4-ethoxyphenyl~-2-methylpropyl ether and 0.1% of unreacted starting 3-phenoxybenzyl 2-(3-iodo-4-ethoxyphenyl)-2-methylpropyl ether, and that the content of each of 3-phenoxytoluene and 4-ethoxyneophyl alcohol formed by cleaving of the ether linkage was lower than 0.3~. The amount of the obtained oily product was 26.0 g and the yield was 95.1%.

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The dechlorination reaction was carried out in the same manner as in Example 1 except that 1.44 g of 1~%-palladium-alumina (100% dry) was used instead of the 5%-palladium-carbon used as the hydrogena$ion catalyst in Example l, and an oily product was o~tained by carrying out the post-treatment in th~ same manner as in Example 1.
From the results of the analysis of the oily product by gas chromatography according to the internal standard method, it was found that the oily product comprised 97~4%
of 3-phenoxybenzyl 2-~4-ethoxyphenyl)-2-methylpropyl ether and 0.5~ of unreacted starting 3-phenoxybenzyl 2-(3-chloro-4-ethoxyphenyl)-2-methylpropyl ether, and that the content of each of 3-phenoxytoluene and 4-ethoxyneophyl alcohol formed by ~leaving of the ether linkage was lower than 0.7%. The amount of ~he obtained oily product was 52.0 g and the yield was 93.2~.
Comparati~e Example An autoclave having a capacity of 300 m~ was charged with 60.0 g (0.145 mole~ of 3-phenoxybenzyl 2-(3-chloro-4-ethoxyphenyl)-2~methylpropyl ether, 29.8 g (0.438 mole) of sodium formate, 4.8 g of 5~-palladium-carbon (50% wet) and 144 m~ of water, and the mixture was heated with stirring at an inner temperature of 110 G C for 12 hours to complete 25 reaction.
The reaction mixture was cooled to room temperature, and 100 m~ of benzene was added into the reaction vessel to dissol~e the oily portion. Then, the catalyst was removed by filtration and the filtrate was allowed to ~0 stand still to cause phase separation to obtain a benzene layer. The benzene layer was washed with 100 m~ of water three times, and benzene was removed by distillation under reduced pressure to give an oil product. From the results of the analysis of the oily product by gas chromatography 35 according to the internal standard method, it was found r that the oil product comprised 65.8% of 3-phenoxybenzyl 2-' .

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(4-ethoxyphenyl)-2-methylpropyl ether, 21.~ of unreacted starting 3-phenoxybenzyl 2-(3-chloro-4-ethoxyphenyl)-2-methylpropyl ether, and 4.4% of 3-phenoxytoluene and 2.9%
of 4-ethoxyneophyl alcohol as by-products formed by cleav-ing of the ether linkage. The amount of the obtained oilyproduct was 57.4 g and the yield was 68.7%.

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Claims (6)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A process for the preparation of 3-phenoxy-benzyl 2-(4-alkoxyphenyl)-2-methylpropyl ethers represented by the following formula (I):

(I) wherein R stands for a lower alkyl group, and X1 and X2 stand for a hydrogen atom or fluorine atom, which comprises subjecting a 3-phenoxybenzyl 2-(4-alkoxy-3-halogenophenyl)-2-methylpropyl ether or 3-phenoxybenzyl 2-(4-alkoxy-3,5-dihalogenophenyl)-2-methylpropyl ether represented by the following formula (II):

(II) wherein R stands for a lower alkyl group, X1 and X2 stand for a hydrogen atom or fluorine atom, and Y1 and Y2 stand for a hydrogen atom, chlorine atom, bromine atom or iodine atom, with the proviso that at least one of Y1 and Y2 is a chlorine atom, bromine atom or iodine atom, to dechlorination, debromination or deiodination by hydrogenation in the presence of a dehydrohalogenating base in an amount of 1 to 10 moles per mole of the compound of formula (II), wherein the dechlorination, debromination or deiodination is carried out in the presence of a hydro-genation catalyst by using as a hydrogenative reducing agent a lower aliphatic alcohol in an amount of at least 0.4 mole of the stoichiometric amount per mole of the compound of formula (II) and an alkali compound selected from alkali metal hydroxides in an amount of at least 0.7 mole of the stoichiometric amount per mole of the compound of formula (II), without introducing hydrogen from outside of the reaction system.

2. A process according to claim 1, wherein said alkali compound is sodium hydroxide.

3. A process according to claim 1, wherein both said dehydrohalogenating base and said alkali compound are sodium hydroxide.

4. A process according to claim 1, wherein said lower aliphatic alcohol is methanol.

5. A process according to claim 1, wherein said hydrogenation catalyst is a palladium catalyst.

6. A process according to claim 1, wherein said dechlorination, debromination or deiodination by hydrogenation is performed in the presence of an aqueous phase.