CA1248969A - Trifluoromethyl benzal chlorides and process for the preparation thereof - Google Patents
Trifluoromethyl benzal chlorides and process for the preparation thereofInfo
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- CA1248969A CA1248969A CA000389124A CA389124A CA1248969A CA 1248969 A CA1248969 A CA 1248969A CA 000389124 A CA000389124 A CA 000389124A CA 389124 A CA389124 A CA 389124A CA 1248969 A CA1248969 A CA 1248969A
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- trifluoromethyl
- benzal
- trichloromethyl
- xylene
- benzal chloride
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Abstract
NOVEL TRIFLUOROMETHYL BENZAL CHLORIDES
AND PROCESS FOR THE PREPARATION THEREOF
ABSTRACT
Novel meta- and para-trifluoromethyl benzal chlorides and ring-halogenated derivatives are useful chemical intermediates for the preparation of meta- and para-trifluoromethyl benzaldehydes and various other useful end products. The novel compounds can be prepared from readily-available xylene starting materials in a process comprising (a) chlorinating meta- or para-xylene, or a ring-halogenated meta- or para-xylene, to form a trichloromethyl benzal chloride product and (B) reacting the trichloromethyl benzal chloride product with about 3 moles or less of anhydrous hydrogen fluoride in the presence of a halogen exchange catalyst.
AND PROCESS FOR THE PREPARATION THEREOF
ABSTRACT
Novel meta- and para-trifluoromethyl benzal chlorides and ring-halogenated derivatives are useful chemical intermediates for the preparation of meta- and para-trifluoromethyl benzaldehydes and various other useful end products. The novel compounds can be prepared from readily-available xylene starting materials in a process comprising (a) chlorinating meta- or para-xylene, or a ring-halogenated meta- or para-xylene, to form a trichloromethyl benzal chloride product and (B) reacting the trichloromethyl benzal chloride product with about 3 moles or less of anhydrous hydrogen fluoride in the presence of a halogen exchange catalyst.
Description
~ ~41~9~9 Case 4308 ASC/lm 10/9/~30 NOVEL TRIFLUOROMETHYL BENZAL CHLORIDES
AND PROCESS FOR THE PREPARATION THEREOF
BACKGROUND OF THE INVENTION
This invention relates to novel compounds, in particular, meta- and para-trifluoromethyl benzal chlorides, and to a method for the preparation thereof. The meta- and para-trifluororllethyl benzal chlorides and ring-halogenated derivatives thereof useful as chemical intermediates for the production oF pesticides and various other useful end products.
It is known from the chemical literature (Balanos et al, J. Chem.
Soc., 4003, 1960; and Belcher et al, Anal. Chim. Acta, 10, 34, 1954) that o-trichloromethyl benzal chloride may be reacted with anhydrous hydrogen fluoride at elevated temperatures under high pressure, -in the absence of a catalyst, to yield o-trifluoromethyl benzal chloride.
SUMMARY OF THE I_IVENTION
It has now been found that meta- or para-trifluoromethyl benzal chlorides of the formula CHCl 1 i ~ J 1 3 ~herein Rl and R2 are independently selected from the group consisting o-f hydrogen, Fluorine, chlorine and bromine are particularly advanta-geous chemical intermediates, for use in the preparation of m- or p-trifluoromethyl benzaldehyde, and various other useful end products.
These novel and useful compounds may be prepared by contacting a meta- or para-trichloromethyl benzal chloride of the formula h~
~4~ ,g Rl _ _ ~ __ CC13 R '~
wherein Rl and R2 are as defined above, with anhydrous hydrogen fluoride in the presence of Q hàloyen transfer catalyst.
It is a particular advantage of the process of this invention that meta- and para-trifluoromethyl benzal chlorides may be readily prepared in high yields at moderate temperatures and wit.hout the need for high pressures.
Various trichloromethyl benzal chlorides and substituted trichloro-methyl benzal chlorides may be employed as reactants in the process of this invention to prepare correspondingly substituted or unsubstituted trifluoromethyl benzal chlorides. The preferred reactants for the process are the meta- and para-trichloromethyl benzal chlorides and the ring halogenated derivatives of these coMpounds, including, for example,
AND PROCESS FOR THE PREPARATION THEREOF
BACKGROUND OF THE INVENTION
This invention relates to novel compounds, in particular, meta- and para-trifluoromethyl benzal chlorides, and to a method for the preparation thereof. The meta- and para-trifluororllethyl benzal chlorides and ring-halogenated derivatives thereof useful as chemical intermediates for the production oF pesticides and various other useful end products.
It is known from the chemical literature (Balanos et al, J. Chem.
Soc., 4003, 1960; and Belcher et al, Anal. Chim. Acta, 10, 34, 1954) that o-trichloromethyl benzal chloride may be reacted with anhydrous hydrogen fluoride at elevated temperatures under high pressure, -in the absence of a catalyst, to yield o-trifluoromethyl benzal chloride.
SUMMARY OF THE I_IVENTION
It has now been found that meta- or para-trifluoromethyl benzal chlorides of the formula CHCl 1 i ~ J 1 3 ~herein Rl and R2 are independently selected from the group consisting o-f hydrogen, Fluorine, chlorine and bromine are particularly advanta-geous chemical intermediates, for use in the preparation of m- or p-trifluoromethyl benzaldehyde, and various other useful end products.
These novel and useful compounds may be prepared by contacting a meta- or para-trichloromethyl benzal chloride of the formula h~
~4~ ,g Rl _ _ ~ __ CC13 R '~
wherein Rl and R2 are as defined above, with anhydrous hydrogen fluoride in the presence of Q hàloyen transfer catalyst.
It is a particular advantage of the process of this invention that meta- and para-trifluoromethyl benzal chlorides may be readily prepared in high yields at moderate temperatures and wit.hout the need for high pressures.
Various trichloromethyl benzal chlorides and substituted trichloro-methyl benzal chlorides may be employed as reactants in the process of this invention to prepare correspondingly substituted or unsubstituted trifluoromethyl benzal chlorides. The preferred reactants for the process are the meta- and para-trichloromethyl benzal chlorides and the ring halogenated derivatives of these coMpounds, including, for example,
2-chloro-3-trichloromethyl benzal chloride; 2-chloro-5-trichloromethyl benzal chloride; 3-trichloromethvl-4-chloro benzal chloride; 3-chloro-5-trichloromethyl benzal chloride; 2,5-dichloro-3-trichloromethyl benzal chloride; 2,4-dichloro-3-trichloromethyl benzal chloride; 2,6-dichloro-
3-trichloromethyl benzal chloride; 2-fluoro-3-trichloromethyl benzal chloride; 2-fluoro-5-trichloromethyl benzal chloride; 3-trichloromethyl-Z0 4-fluoro benzal chloride; 3-fluoro-5-trichloromethyl benzal chloride;
2,5-difluoro-3-trichloromethyl benzal chloride; 2-bromo-3-trichloromethyl benzal chloride; 2-bromo-5-trichloronnethyl benzal chloride; 3-bromo-5-trichloromethyl benzal chloride; 2-chloro-4-trichloromethyl benzal chloride; 3-chloro-4-trichloromethyl benzal chloride; 2,5-dichloro-4-trichloromethyl benzal chloridei 2-fluoro-4-trichloromethyl benzal chloride; 3-fluoro-4-trichloromethyl benzal chloride; 2,5-difluoro-3-trichloromethyl benzal chloride; 2-bromo-4-trichloromethyl benzal chloride; 3-bromo-4-trichloromethyl benzal chloride and the like.
~2~L~9~i9 The fluorirlation is carrieci out in the presence of a halogen transfer catalyst. Such catalysts are well known in literature and inclucle for example ferric chloride, aluminum chloride, molyb-denum pentachloride, titanium tetrachloride, antimony pentafluoride, antimony pentachloride, antimony-V-chloride-fluoride, and the like.
The preferred catalyst is antimony pentachloride. Typically, fihe catalyst is employed in amoun-ts of about 0.1 to about 10 percent by weight and preferably about 0.5 to about 5 percent by weight based on the weight of trichloromethyl benzal chloride starting material. To assure completion of the reaction and maximum yield of the desired trifluoromethyl benzal chloride, it has been found advantageous to add more halogen transfer catalyst, such as about 0.1 to about 10 percent by weight based on the weight of the reaction mixture, after the addition of hydrogen fluoride is completed, and to maintain a temperature of about 40 to about 150 Celsius for an additional period of time, such as up to about two hours.
The fluorination may be carried out over a wide range of condi-tions. The process may be carried out at atmospheric pressure or at superatmospheric pressures, preferably in the range o-F up to about 3 atmospheres. The suitability of atmospheric pressure is a particu-lar advantage and a preferred mode of the process of this invention.
Process temperatures may vary considerably but are preferably in the range of about 40 to about 150 Celsius.
Although it is preferred to carry out the process neat, a suitable inert solvent, such as nitrobenzene, carbon disulfide and the like may be employed if desired.
The novel meta- and para-trifluoromethyl benzal chlorides of this invention may be economically prepared from readily available, inexpensive starting materials in a simple, direct manner, requiring relatively few process steps. Thus, for example, xylene may be chlorinated in a known manner such as photochlorination at tempera-tures in the range of about 20 to about 200 Celsius in the presence of actinic light, such as ultra violet light, while con-~2~L~39~
trolling the amount o-f chlorine reacted to yield a reaction pro-duct containing trichloromethyl benzal chloride as the major com-ponent. Over chlorinated components may be readily removed by physical separation means, such as distillation. Alternatively the crude reaction product may be employed in the fluorination step and unwanted components may be removed, if desired, following the fluorination step. The trichloromethyl benzal chloride is reacted with about three moles of anhydrous hydrogen fluoride in the pre-sence of a halogen transfer catalyst in the manner described herein-lo above to yield trifluoromethyl benzal chloride. Thus, in a simple direct method, meta- or para-trifluoromethyl benzal chloride may be synthesized from a readily available commodity chemical, such as meta- or para-xylene. In a similar manner, various ring-halogenated meta- or para-xylenes may be employed as starting materials to produce correspondingly substituted trifluoromethyl benzal chlorides.
In a particula~ embodiment, the present invention provides a process for the preparation of novel meta- or para-trifluoro-methyl benzal chlorides comprising the steps of (A) chlorinating meta- or para-xylene, or a rins-halogenated meta- or para-xylene to form a trichloromethyl benzal chloride product, (B) reacting the trichloromethyl benzal chloride with about three moles or less of anhydrous hydrogen fluoride in the presence of a halogen transfer catalyst.
The meta- and para-trifluoromethyl benzal chloride, in accor-dance with this invention, are particularly useful as intermediates in the further preparation of meta- and para-trifluoromethyl benzal-dehydes. ~uch preparation is readily accomplished by hydrolysis of the selected m- or p-trifluoromethyl benzal chloride. The hydrolysis reaction is carried out in the presence of about 0.1 to about 10 parts by weight of ferric chloride, based on the weight of benzal chloride, and is typically carried out at a temperature of about 75 to about 100 and preferably about ~0 to about 100 Celsius.
~L248~
Thus, in another aspect the present invention provides a process for the preparation of meta- or para-trifluoromethyl benzaldehydes from meta- or para-xylenes comprising the steps of (A) chlorinating meta- or para-xylene or a ring-halogenated meta- or para-xylene, to form a trichloromethyl benzal chloride product, (B) reacting the trichloromethyl benzal chloride with about 3 moles or less of anhydrous hydrogen fluoride in the presence of a halogen transfer catalyst to form the corresponding t-rifluoromethyl benzal chloride, and (C) hydrolysis of the latter to 2Orm the corresponding meta- or para-trifluoromethyl benzaldehyde.
The following specific examples are provided to further illus-trate the invention in a manner in which they be carried out. It will be understood, however, that the specific details given in the examples have been chosen for purposes of illustration and are not to be construed as a limitation on the invention. In the examples, uniess otherwise indica-ted, all parts and percentages are by weight and all temperatures are in degrees Celsius.
EXAMPLE I
A mixture of 99.5 parts of p-trichloromethyl benzal chloride and about 1.5 parts of antimony pentachloride was heated and maintained at a temperature oF 75-77C with stirring while 22 parts of hydrogen fluoride was added slowly over a period about 11 minutes. The reaction mixture was maintained at about that temperature, with stirring, for an additional hour, then purged with nitrogen and cooled to room tempera-ture. The reaction product was treated with methylene chloride and with sodium carbonate, filtered to remove the sodium carbonate and catalyst, then distilled to remove methylene chloride. The remain-ing reaction product, 620 parts, was analyzed by gas chromatographic techniques and found to contain about 85.6,~ of p-trifluoromethyl benzal chloride, representing a yield of about 65% based on the p-trichioromethyl benzal chloride reactan-t.
~2~ 69 The procedure of Example 1 is repeated except that in place of the p-trichloromethyl benzal chloride reactant, there is substitut-ed an approximately equimolar amount of 2-chloro-4-trichloromethyl benzal chloride. The fluorination reaction product contains aS a major component thereof, 2-chloro-4-trifluoromethyl benzal chloride.
Following the general procedure of Example 1, a mixture o-f 100 pa~ts of p-trichloromethyl benzal chloride and about 1.5 parts of lo antinlony pentachloride was heated and maintained at about 89-99C
while 26 parts of hydrogen fluoride was added slowly with stirring over a period of about 13 minutes. The temperature was maintained, and stirring continued for an additional 1.5 hours. The reaction mixture was then cooled to room temperature, purged with nitrogen;
treated with methylene chloride and with sodium carbonate; filtered;
and the methylene chloride removed by distillation. The remaining crude reaction product (36 parts by weight) was analyzed by gas chromatography and found to contain approximately 76% of p-tri-fluoromethyl benzal chloride.
P-xylene was heated to 150C and irradiated with an ultraviolet light source while chlorine gas was bubbled in. The photochlorination was continued until pentachloroxylene (i.e. p-trichloromethyl benzal chloride) constituted greater than 50% of the reaction mixture. The reaction mixture was then distilled using a packed column at a pressure of 5 torr and a pot temperature of 180C. A major fraction comprising about 70.~0 of p-trichloromethyl benzal chloride, taken at a head temperature of about 145 to 149C was separated from the reaction mixture. A mixture of 127 parts of this major fraction and 1.33 parts of antimony pentachloride was heated to 110C and maintained at that temperature while 34 parts of anhydrous hydrogen fluoride was added over a 3 hour period. The mixture was cooled -to L8~3~i9 about 50C. The excess hydrogen fluoride was removed and an addi-tional 1.33 parts of antimony pentachloride added. After two hours the reaction mixture was cooled to about 25C, slurried with sodium carbonate, filtered, washed with 6N hydrochloric acid, and dried.
Distillation at 5 torr, 98C, yielded 32 parts of p-trifluoromethyl benzal chloride.
Following the procedure of Example 4, m-xylene is heated to about 150C and irradia-ted with ultraviolet light while chlorine gas is bubbled in until pentachloroxylene (i.e. m-trichloromethyl benzal chloride constitutes greater than 50% of the reaction mixture.
The reaction mixture is distilled to separate a fraction thereof having a higher concentration of the m-trichloromethyl benzal chloride. This fraction is then mixed with 1 to 2 parts of antimony pentachloride and the mixture heated to about 110C and maintained thereat while about 34 parts of hydrogen fluoride is added over about a 3 hour period. The reaction product includes m-trifluoro-methyl benzal chloride as a major component thereof.
The procedure of Example 1 is repeated except that in place of the p-trichloromethyl benzal chloride reactant there is substituted an approxinlately equimolar amount of 2,5-dichloro-3-trichloromethyl benzal chloride, and the temperature of the reaction is increased to about 115C. Following the fluorination reaction the product 2,5-dichloro-3-trifluoromethyl benzal chloride is recovered from the reaction mixture.
A mixture of 128 parts of p-trifluoromethyl benzal chloride and 0.5 parts of ferric chloride was heated -to about 95-100C, and maintained at that temperature, with stirring, while 10 parts of water was added slowly, over a period of 3 hours. The reaction mixture was retained at temperature, with stirring, for an additional hour, then distilled to separate 80 parts of p-trifluoromethyl benzaldehyde (b.p. 72 at 15 torr), having a purity of 97%, based on analysis by gas chromatographic techniques. The yield of p-trifluoro-methyl benzaldehyde was about 85%, based on p-trifluoromethyl benzal chloride reactant.
2,5-difluoro-3-trichloromethyl benzal chloride; 2-bromo-3-trichloromethyl benzal chloride; 2-bromo-5-trichloronnethyl benzal chloride; 3-bromo-5-trichloromethyl benzal chloride; 2-chloro-4-trichloromethyl benzal chloride; 3-chloro-4-trichloromethyl benzal chloride; 2,5-dichloro-4-trichloromethyl benzal chloridei 2-fluoro-4-trichloromethyl benzal chloride; 3-fluoro-4-trichloromethyl benzal chloride; 2,5-difluoro-3-trichloromethyl benzal chloride; 2-bromo-4-trichloromethyl benzal chloride; 3-bromo-4-trichloromethyl benzal chloride and the like.
~2~L~9~i9 The fluorirlation is carrieci out in the presence of a halogen transfer catalyst. Such catalysts are well known in literature and inclucle for example ferric chloride, aluminum chloride, molyb-denum pentachloride, titanium tetrachloride, antimony pentafluoride, antimony pentachloride, antimony-V-chloride-fluoride, and the like.
The preferred catalyst is antimony pentachloride. Typically, fihe catalyst is employed in amoun-ts of about 0.1 to about 10 percent by weight and preferably about 0.5 to about 5 percent by weight based on the weight of trichloromethyl benzal chloride starting material. To assure completion of the reaction and maximum yield of the desired trifluoromethyl benzal chloride, it has been found advantageous to add more halogen transfer catalyst, such as about 0.1 to about 10 percent by weight based on the weight of the reaction mixture, after the addition of hydrogen fluoride is completed, and to maintain a temperature of about 40 to about 150 Celsius for an additional period of time, such as up to about two hours.
The fluorination may be carried out over a wide range of condi-tions. The process may be carried out at atmospheric pressure or at superatmospheric pressures, preferably in the range o-F up to about 3 atmospheres. The suitability of atmospheric pressure is a particu-lar advantage and a preferred mode of the process of this invention.
Process temperatures may vary considerably but are preferably in the range of about 40 to about 150 Celsius.
Although it is preferred to carry out the process neat, a suitable inert solvent, such as nitrobenzene, carbon disulfide and the like may be employed if desired.
The novel meta- and para-trifluoromethyl benzal chlorides of this invention may be economically prepared from readily available, inexpensive starting materials in a simple, direct manner, requiring relatively few process steps. Thus, for example, xylene may be chlorinated in a known manner such as photochlorination at tempera-tures in the range of about 20 to about 200 Celsius in the presence of actinic light, such as ultra violet light, while con-~2~L~39~
trolling the amount o-f chlorine reacted to yield a reaction pro-duct containing trichloromethyl benzal chloride as the major com-ponent. Over chlorinated components may be readily removed by physical separation means, such as distillation. Alternatively the crude reaction product may be employed in the fluorination step and unwanted components may be removed, if desired, following the fluorination step. The trichloromethyl benzal chloride is reacted with about three moles of anhydrous hydrogen fluoride in the pre-sence of a halogen transfer catalyst in the manner described herein-lo above to yield trifluoromethyl benzal chloride. Thus, in a simple direct method, meta- or para-trifluoromethyl benzal chloride may be synthesized from a readily available commodity chemical, such as meta- or para-xylene. In a similar manner, various ring-halogenated meta- or para-xylenes may be employed as starting materials to produce correspondingly substituted trifluoromethyl benzal chlorides.
In a particula~ embodiment, the present invention provides a process for the preparation of novel meta- or para-trifluoro-methyl benzal chlorides comprising the steps of (A) chlorinating meta- or para-xylene, or a rins-halogenated meta- or para-xylene to form a trichloromethyl benzal chloride product, (B) reacting the trichloromethyl benzal chloride with about three moles or less of anhydrous hydrogen fluoride in the presence of a halogen transfer catalyst.
The meta- and para-trifluoromethyl benzal chloride, in accor-dance with this invention, are particularly useful as intermediates in the further preparation of meta- and para-trifluoromethyl benzal-dehydes. ~uch preparation is readily accomplished by hydrolysis of the selected m- or p-trifluoromethyl benzal chloride. The hydrolysis reaction is carried out in the presence of about 0.1 to about 10 parts by weight of ferric chloride, based on the weight of benzal chloride, and is typically carried out at a temperature of about 75 to about 100 and preferably about ~0 to about 100 Celsius.
~L248~
Thus, in another aspect the present invention provides a process for the preparation of meta- or para-trifluoromethyl benzaldehydes from meta- or para-xylenes comprising the steps of (A) chlorinating meta- or para-xylene or a ring-halogenated meta- or para-xylene, to form a trichloromethyl benzal chloride product, (B) reacting the trichloromethyl benzal chloride with about 3 moles or less of anhydrous hydrogen fluoride in the presence of a halogen transfer catalyst to form the corresponding t-rifluoromethyl benzal chloride, and (C) hydrolysis of the latter to 2Orm the corresponding meta- or para-trifluoromethyl benzaldehyde.
The following specific examples are provided to further illus-trate the invention in a manner in which they be carried out. It will be understood, however, that the specific details given in the examples have been chosen for purposes of illustration and are not to be construed as a limitation on the invention. In the examples, uniess otherwise indica-ted, all parts and percentages are by weight and all temperatures are in degrees Celsius.
EXAMPLE I
A mixture of 99.5 parts of p-trichloromethyl benzal chloride and about 1.5 parts of antimony pentachloride was heated and maintained at a temperature oF 75-77C with stirring while 22 parts of hydrogen fluoride was added slowly over a period about 11 minutes. The reaction mixture was maintained at about that temperature, with stirring, for an additional hour, then purged with nitrogen and cooled to room tempera-ture. The reaction product was treated with methylene chloride and with sodium carbonate, filtered to remove the sodium carbonate and catalyst, then distilled to remove methylene chloride. The remain-ing reaction product, 620 parts, was analyzed by gas chromatographic techniques and found to contain about 85.6,~ of p-trifluoromethyl benzal chloride, representing a yield of about 65% based on the p-trichioromethyl benzal chloride reactan-t.
~2~ 69 The procedure of Example 1 is repeated except that in place of the p-trichloromethyl benzal chloride reactant, there is substitut-ed an approximately equimolar amount of 2-chloro-4-trichloromethyl benzal chloride. The fluorination reaction product contains aS a major component thereof, 2-chloro-4-trifluoromethyl benzal chloride.
Following the general procedure of Example 1, a mixture o-f 100 pa~ts of p-trichloromethyl benzal chloride and about 1.5 parts of lo antinlony pentachloride was heated and maintained at about 89-99C
while 26 parts of hydrogen fluoride was added slowly with stirring over a period of about 13 minutes. The temperature was maintained, and stirring continued for an additional 1.5 hours. The reaction mixture was then cooled to room temperature, purged with nitrogen;
treated with methylene chloride and with sodium carbonate; filtered;
and the methylene chloride removed by distillation. The remaining crude reaction product (36 parts by weight) was analyzed by gas chromatography and found to contain approximately 76% of p-tri-fluoromethyl benzal chloride.
P-xylene was heated to 150C and irradiated with an ultraviolet light source while chlorine gas was bubbled in. The photochlorination was continued until pentachloroxylene (i.e. p-trichloromethyl benzal chloride) constituted greater than 50% of the reaction mixture. The reaction mixture was then distilled using a packed column at a pressure of 5 torr and a pot temperature of 180C. A major fraction comprising about 70.~0 of p-trichloromethyl benzal chloride, taken at a head temperature of about 145 to 149C was separated from the reaction mixture. A mixture of 127 parts of this major fraction and 1.33 parts of antimony pentachloride was heated to 110C and maintained at that temperature while 34 parts of anhydrous hydrogen fluoride was added over a 3 hour period. The mixture was cooled -to L8~3~i9 about 50C. The excess hydrogen fluoride was removed and an addi-tional 1.33 parts of antimony pentachloride added. After two hours the reaction mixture was cooled to about 25C, slurried with sodium carbonate, filtered, washed with 6N hydrochloric acid, and dried.
Distillation at 5 torr, 98C, yielded 32 parts of p-trifluoromethyl benzal chloride.
Following the procedure of Example 4, m-xylene is heated to about 150C and irradia-ted with ultraviolet light while chlorine gas is bubbled in until pentachloroxylene (i.e. m-trichloromethyl benzal chloride constitutes greater than 50% of the reaction mixture.
The reaction mixture is distilled to separate a fraction thereof having a higher concentration of the m-trichloromethyl benzal chloride. This fraction is then mixed with 1 to 2 parts of antimony pentachloride and the mixture heated to about 110C and maintained thereat while about 34 parts of hydrogen fluoride is added over about a 3 hour period. The reaction product includes m-trifluoro-methyl benzal chloride as a major component thereof.
The procedure of Example 1 is repeated except that in place of the p-trichloromethyl benzal chloride reactant there is substituted an approxinlately equimolar amount of 2,5-dichloro-3-trichloromethyl benzal chloride, and the temperature of the reaction is increased to about 115C. Following the fluorination reaction the product 2,5-dichloro-3-trifluoromethyl benzal chloride is recovered from the reaction mixture.
A mixture of 128 parts of p-trifluoromethyl benzal chloride and 0.5 parts of ferric chloride was heated -to about 95-100C, and maintained at that temperature, with stirring, while 10 parts of water was added slowly, over a period of 3 hours. The reaction mixture was retained at temperature, with stirring, for an additional hour, then distilled to separate 80 parts of p-trifluoromethyl benzaldehyde (b.p. 72 at 15 torr), having a purity of 97%, based on analysis by gas chromatographic techniques. The yield of p-trifluoro-methyl benzaldehyde was about 85%, based on p-trifluoromethyl benzal chloride reactant.
Claims
The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:
m-trifluoromethyl benzal chloride.
p-trifluorornethyl benzal chloride.
A process for the preparation of meta- or para-trifluoromethyl benzal chlorides of the formula wherein R1 and R2 are independently selected from the group consisting of hydrogen, fluorine, chlorine and bromine, which comprises A) chlorinating meta- or para-xylene of the formula where R1 and R2 are as previously defined to form trichloromethyl benzal chloride of the formula where R1 and R2 are as previously defined; and B) reacting the trichloromethyl benzal chloride with about 3 moles or less of anhydrous hydrogen fluoride in the presence of a halogen transfer catalyst.
A process according to Claim 1 wherein the xylene of step (A) is m-xylene, and the product of step (B) is m-trifluoromethyl benzal chloride.
A process according to Claim 1 wherein the xylene of step (A) is p-xylene and the product of step (B) is p-trifluoromethyl benzal chloride.
A process according to Claim 5 wherein step (B) is carried out at a temperature of about 40° to about 150° Celsius.
A process according to Claim 6 wherein the halogen transfer catalyst is antimony pentachloride.
A process for the preparation of m- or p-trifluoromethyl benzal-dehyde of the formula wherein R1 and R2 are independently selected from the group consisting of hydrogen fluorine, chlorine and bromine, which comprises A) chlorinating meta- or para-xylene of the formula where R1 and R2 are as previously defined to form trichloromethyl benzal chloride of the formula where R1 and R2 are as previously defined; and B) reacting the trichloromethyl benzal chloride with about 3 moles or less of anhydrous hydrogen fluoride in the presence of a halogen transfer catalyst to form a trifluoromethyl benzal chloride of the formula where R1 and R2 are as previously defined; and C) hydrolyzing the trifluoromethyl benzal chloride to form a tri-fluoromethyl benzaldehyde product.
A process according to Claim 8 wherein the xylene of step A is m-xylene and the product of step (C) is m-trifluoromethyl benzaldehyde.
A process according to Claim 8 wherein the xylene of step (A) is p-xylene and the product of step (C) is p-trifluoromethyl benzaldehyde.
A process according to Claim 10 wherein the halogen transfer catalyst is antimony pentachloride.
m-trifluoromethyl benzal chloride.
p-trifluorornethyl benzal chloride.
A process for the preparation of meta- or para-trifluoromethyl benzal chlorides of the formula wherein R1 and R2 are independently selected from the group consisting of hydrogen, fluorine, chlorine and bromine, which comprises A) chlorinating meta- or para-xylene of the formula where R1 and R2 are as previously defined to form trichloromethyl benzal chloride of the formula where R1 and R2 are as previously defined; and B) reacting the trichloromethyl benzal chloride with about 3 moles or less of anhydrous hydrogen fluoride in the presence of a halogen transfer catalyst.
A process according to Claim 1 wherein the xylene of step (A) is m-xylene, and the product of step (B) is m-trifluoromethyl benzal chloride.
A process according to Claim 1 wherein the xylene of step (A) is p-xylene and the product of step (B) is p-trifluoromethyl benzal chloride.
A process according to Claim 5 wherein step (B) is carried out at a temperature of about 40° to about 150° Celsius.
A process according to Claim 6 wherein the halogen transfer catalyst is antimony pentachloride.
A process for the preparation of m- or p-trifluoromethyl benzal-dehyde of the formula wherein R1 and R2 are independently selected from the group consisting of hydrogen fluorine, chlorine and bromine, which comprises A) chlorinating meta- or para-xylene of the formula where R1 and R2 are as previously defined to form trichloromethyl benzal chloride of the formula where R1 and R2 are as previously defined; and B) reacting the trichloromethyl benzal chloride with about 3 moles or less of anhydrous hydrogen fluoride in the presence of a halogen transfer catalyst to form a trifluoromethyl benzal chloride of the formula where R1 and R2 are as previously defined; and C) hydrolyzing the trifluoromethyl benzal chloride to form a tri-fluoromethyl benzaldehyde product.
A process according to Claim 8 wherein the xylene of step A is m-xylene and the product of step (C) is m-trifluoromethyl benzaldehyde.
A process according to Claim 8 wherein the xylene of step (A) is p-xylene and the product of step (C) is p-trifluoromethyl benzaldehyde.
A process according to Claim 10 wherein the halogen transfer catalyst is antimony pentachloride.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000389124A CA1248969A (en) | 1981-10-30 | 1981-10-30 | Trifluoromethyl benzal chlorides and process for the preparation thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000389124A CA1248969A (en) | 1981-10-30 | 1981-10-30 | Trifluoromethyl benzal chlorides and process for the preparation thereof |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1248969A true CA1248969A (en) | 1989-01-17 |
Family
ID=4121306
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000389124A Expired CA1248969A (en) | 1981-10-30 | 1981-10-30 | Trifluoromethyl benzal chlorides and process for the preparation thereof |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1248969A (en) |
-
1981
- 1981-10-30 CA CA000389124A patent/CA1248969A/en not_active Expired
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |