CA1118455A - Dehydrohalogenation of (polyhaloalkyl) benzenes - Google Patents
Dehydrohalogenation of (polyhaloalkyl) benzenesInfo
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- CA1118455A CA1118455A CA000336836A CA336836A CA1118455A CA 1118455 A CA1118455 A CA 1118455A CA 000336836 A CA000336836 A CA 000336836A CA 336836 A CA336836 A CA 336836A CA 1118455 A CA1118455 A CA 1118455A
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- polyhaloalkyl
- benzene
- arene
- alkyl
- ticl4
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Abstract
Abstract A process for the dehydrohalogenation of a (polyhaloalkyl)benzene containing a benzylic halogen such as 1,3-dichloro-5-(1,3,3,3-tetrachloro-1-methyl-propyl)benzene by contacting the (polyhaloalkyl)benzene with a suitably active Lewis acid catalyst such as SbCl5 or TiCl4, under conditions sufficient to catalyze the dehydrohalogenation to form a (polyhaloalkenyl)-benzene such as 3,5-dichloro-a-(2,2,2-trichloroethyl)-styrene.
26,164-F
26,164-F
Description
1~845S
PROCESS FOR ~EHYDROHALOGENATING (POLYHALOALI~YL)BENZENES
This invention relates to processes for pre-paring (haloalkenyl)benzenes including (polyhaloalkenyl)-S benzenes.
~ Haloalkyl)styrenes are useful as para~
siticides and insecticides. They are also useful intermediates in the manufacture of other biologically active compounds. Such compounds are conventionally prepared by reacting a halogenated organic compound with an a-methylstyrene in the presence of a free--radical initiator which usually comprises an organic amine and a copper-containing material. These known methods for preparing haloalkenylber.z2nes require long reaction times and undesirably high reaction temperatures and give somewhat low yields of product.
In accordance with the present invention, (haloalkenyl)benzenes and other (haloalkenyl)arenes are advantageously obtained by a dehydrohalogenation process, which comprises contacting a (polyhaloalkyl)arene in which polyhaloalkyl has a benzylic halogen and at least 26,16~-~
~L
ll~B4S5 one non-benzylic aliphatic halogen with a catalytic amount of a halide of titanium which has been treated with water and is in neat form or a halide of antimony in neat form in the liquid phase at temperatures below 100C. Surprisingly, the benzylic halogen of the poly-haloalkyl group is selectively eliminated to form the desired (haloalkenyl)arene while the non-benzylic aliphatic halogen(s) are left undisturbe~. The ~haio-alkenyl)benzenes produced in the practice of this invention are useful as biologically active compounds as described hereinbefore and as intermediates in the preparation of other biologically active compounds.
By a (polyhaloalkyl)arene is meant an aromatic compound in which an aromatic ring bears at least one polyhaloalkyl substituent. In the polyhaloalkyl substi-tuent, one halogen is bonded to the alkyl carbon bonded to the aromatic ring (hereinafter called a benzylic halogen) and at least one halogen is bonded to one other alkyl carbon (hereinafter called a non-benzylic halogen).
By "arene" is meant an aromatic compound having one or more aromatic rings such as benzene, naphthalene, anthracene as well as substituted arenes. The substi-tuents include halo, nitro, alkyl, alkoxy, alkylthio, axyl, aryloxy, sulfo, carboxy, carboxylate ester, --haloalkyl including polyhaloalkyl, haloaryl and other substituent groups that do not interfere with dehydro-halogenation reactions that are catalyzed by Lewis acids. Such substituents are inert in the dehydro-halogenation reactions.
. Preferred (polyhaloalkyl)arenes are repre-sented by Formula I:
26,164-F -2-111~34~i;~ii CH3-C~Y
Ar (R)n wherein Ar is arene, preferably benzene, each R is indi-vidually halo, alkyl, haloalkyl .ncluding pol~haloa'X-Yl Y .
such as -CX3 (e.g., -CF3) and CH3-C-X wherein X and Y
are as defined herein, aryl, haloaryl, nitro, alkoxy, and other inert monovalent organic radicals, X is halo, Y is haloalkyl or substituted haloalkyl wherein alkyl has from 2 to 3 carbons and the non-halogen substituent or substituents may be, for example, nitro or alkoxy, and n is 0 to the maximum number of remaining available ring positions on Ar. Preferably n is from 0 to 2 when Ar is benzene. More preferably, each ~ is individually halo such as Cl, Br, or F; alkyl having 1 to 4 carbons such as -CH3; alkoxy such as -OCH3 and others having 1 to 4 carbons; and -NO2. Most preferably each R is individually Cl, Br or -N02. X is more preferably Cl or Br, most preferably Cl. Y is more preferably halo-alkyl represented by the formula:
-CH2-C-R ' R' wherein X' is Cl or Br, each R' is individually H, halo such as Cl, Br or F, lower alkyl or -NO2. Most preferably Y is -CH2CCl2R' wherein R' is H, Cl, Br, 26,164-F -3--CH3 or -C2H5. For example, Y is most preferably -CH2CC13, -CH2CCl2Br, -CH2CHCl2 and -CH2CH2Cl.
Examples of especially preferred poly(halo-alkyl)arenes include 1,3-dichloro-5-(1,3,3,3-tetra-chloro-1-methylpropyl)benzene, 1,3-dichloro-5-(1,3,3--trichloro-1-methylpropyl)benzene and similar 1,3--dihalo-5-~polyhalobutyl)benzenes. vther prefei-L-ed (polyhaloalkyl)arenes include 3-chloro-1-(1,3,3,3--tetrachloro-l-methylpxopyl)benzene and similar 3-halo-1-(polyhalobutyl)benzenes.
(Polyhaloalkyl)arenes may be prepared by known methods. For example, ~methylstyrene or ar--substituted methylstyrene is reacted with a poly-haloalkane such as carbon tetrachloride, bromotri-chloromethane, methylene chloride or dichloroni-tromethane in the presence of an amine and cuprous chloride to produce a desired (polyhaloalkyl)benzene.
Lewis acids which are suitably employed in the practice of this invention are the Lewis acids which catalyze the elimination of the benzylic halogen from the (polyhaloalkyl)arene via a dehydrohalogenation reaction while essentially all of the non-benzylic halo- -gen substituent(s) of the (polyhaloalkyl)arene remain bonded to the (polyhaloalkyl)arene. Such Lewis acids are stated herein to be suitably active if, during the preferential dehydrohalogenation of essentially all (>95 mole percent) of benzylic halogen of the (poly-haloalkyl)arene, less than lO, preferably less than 5, mole percent of non-benzylic halogen is eliminated.
26,164-F -4-~1184~;5 Examples of Lewis acids which, in neat (undiluted) form, are suitably active include (1) the halides of titanium, preferably TiC14, which have been treated with water and (2) the halides of antimony, preferably antimony pentachloride. of the neat forms, the titanium tetrahalides which have been treated with from 0.1 to 2 moles of water per mole of the titanium tetrahalide are more preferred, with Ti~14 beir,g treated from 0.25 to 1.75 moles of water per mole of TiC14 being most preferred.
In the practice of this invention, the (polyhaloalkyl)arene is contacted with a catalytic amount of a suitably active Lewis acid under dehy-drohalogenation conditions. A catalytic amount is any amount of suitably active Lewis acid which catalyzes the selective dehyd~ohalogenation of the (polyhaloalkyl)arene such that substantially all of the benzylic halogen thereof is eliminated. Advan-tageously, such catalytic amounts are within the range from 0.1 to 20 weight percent of suitably active Lewis acid based on the weight of (polyhalo-alkyl)arene, preferably from 0.1 to 10 weight percent of the Lewis acid, most preferably from 0.2 to 3 weight percent of the Lewis acid.
In addition to the aforementioned starting ingredients, a solvent such as carbon tetrachloride, ethylene dichloride or similar halohydrocarbons is optionally employed. When used, the solvent is present in an amount between 0.5 and 3 liters of solvent per mole of the (polyhaloalkyl)arene.
26,164 F -5-- ~118A~5 While the temperature of the dehydrohalo-genation reaction is not particularly critical, the reaction is advantageously conducted in the liquid phase at a temperature below 100C, preferably between 25C and 80C, and most preferably between 55C and 80C. Preferably, the suitably active Lewis acid catalyst is added to a stirred mixture of the (poly-haloalkyl)arene and the optior.al solvent. It is sometimes desirable to add the (polyhaloalkyl)arene diluted with solvent to a stirred solution of the catalyst in solvent. Thus, the rate of hydrogen halide evolution is controlled by the slow addition of reactant.
After the (polyhaloalkyl)arene is contacted with catalyst, the reac~ion begins immediately, as evidenced by evolution of hydrogen halide gas. The reaction is allowed to proceed to completion while agitating the reaction mixture sufficiently to keep the catalyst in suspension. The reaction pressure is not critical and is conveniently atmospheric.
The product of the dehydrohalogenation reaction is primarily a (polyhaloalkenyl~arene wherein the benzylic halogen and hydrogen on an adjacent carbon are eliminated. In embodiments of particular interest, the (polyhaloalkenyl)arene is represented by formula II:
CH2=C-Y
Ar II
( R) n 26,164-F -6-P~
111~345~i wherein R, Y and n are ~s defined hereinbefore. In preferred embodiments of this invention, the dehydro-halogenation is sufficiently selective such that more than 95 mole percent of benzylic halogen is eliminated, most preferably more than 99 mole percent, and less than 5 mole percent of non-benzylic halogen is elimi-nated most preferably less than 2 mole percent.
The following examples are given to further illustrate the invention. All percentages in the examples are by weight unless otherwise indicated.
Example 1 Preparation of 3,5-dlchloro-~-methylstyrene Chlorine gas is bubbled through 129 g of 3,5-dichlorotoluene in the presence o~ light until no further adsorption occurs. An increase in weight of 83 g results. To the product, weighing 212 g, is added dropwise 400 g of 8 percent fuming sulfuric acid. After being stirred for 30 hours the mixture is poured over cracked ice. The 3,5-dichlorobenzoic acid which precipitated is washed well with water and dried. It weighs 145 g, or 95 percent yield based on the dichlorotoluene. The acid is converted to 3,5-dichlorobenzoyl chloride in 95 percent yield by treating with 125 g thionyl chloride. The chloride, weighing 151 g, is then allowed to react with 150 ml of methyl alcohol and the resulting methyl 3,5-di--chlorobenzoate, which when distilled at 120C-125C
at 7 mm weighs 133 g, or 90 percent of theory. The ester is treated with 2 equivalents of methyl magnesium chloride (125 g), the Grignard complex hydrolyzed, and the product then dehydrated by refluxing with NaHSO4.
26,164-F -7-.
4 ~ 5 The 3,5-dichloro-~-methylstyrene obtained weighs 88 g, or 72 percent of theory based on the ester used, and boiled at 109C-111C at 12 mm. Its specific gravity is 1.196 and its refractive index is 1.5660, both measured at 25C.
Addition of CC14 The 3,5-dichloro-~-methylstyrene is placed in a 250 ml vessel equipped with stirring means and a heating means. A mixture including 18.7 g (0.1 mole) of 3,5-dichloro-~-methylstyrene, as well as 46.2 g (0.3 mole) of CC14 and 0.4 g of cuprous chloride is formed with stirring. To the mixture is added 1.6 g (0.016 mole) of cyclohexylamine. The mixture is heated to the reflux temperature of CC14 and main-tained at reflux temperature until completion of the reaction in 30 minutes. The reaction mixture is cooled and filtered, and the solvent is removed under vacuum leaving 31.2 g (91.5 percent yield) of residual product. This residue is recrystallized from hexane to yield essentially pure 1,3-dichloro--5-(1,3,3,3-tetrachloro-1-methylpropyl)benzene exhibiting a melting point of 44.5-46.5C.
Dehvdrohaloqenation with SbC15 -A mixture composed of a 137 g (0.40 mole) portion of the 1,3-dichloro-5-(1,3,3,3-tetrachloro--l-methylpropyl)benzene (DCTCB) obtained above and 250 ml of CC14 is formed in a 500 ml flask equipped with a stirring and a heating means. With stirring, a 7 g portion (0.023 mole) of SbC15 is added to the flask and dehydrochlorination (as evidenced by HCl gas) to form a crude product mixture occurs at room 26,164-F -8-g temperature. The crude product mixture is heated to reflux (82~C), is held at this temperature for 30 minutes, and is then allowed to cool to a tem-perature near ambient. To the crude product mixture a 150-ml portion of CCl4 is added and then a 200-ml portion of 3N HCl is added with stirring. An aqueous and an organic layer are formed. The organic and a~ueous layers are separated and 200 ml of water is added to the organic layer with stirring. The organic layer is stirred over Na2S04 to remo~e any water remaining. The carbon tetrachloride present in the organic layer is removed under a vacuum leaving 115.8 g of a crude product. Distillation of the crude product yields 100.2 g (0.33 mole) of product containing at least 95 percent of 3,5-dichloro-~-(2,2,2-trichloro-ethyl)styrene (DCTCS) represented by the structure:
H2C=C-CH2-CCl3 Cl ~ Cl and less than 5 percent of diene represented by the structure:
H2C=C-CH=CC12 I
Cl ~ Cl Example 2 Dehydrohaloqenation with H20 Treated TiCl4 A mixture consisting of 5 g (0.0147 mole) of the DCTCB produced according to Example 1, 50 ml of CCl4 and 0.020 ml of water is placed in a 100 ml 26,164-F -9-flask. The mixture is heated to reflux (about 90C) and 0.173 g (0.000911 mole) of TiC14 is added to the mixture. Evolution of HCl is noted as the reflux continues for 2 hours. The mixture is cooled to 45C and 25 ml of concentrated hydrochloric acid is added. An organic layer and an aqueous layer are formed and separated. The organic layer is washed with wateî. The solvent is then removed from the organic layer in vacuum. The remaining residue which weighs 4.0~ g ~0.0133 mole) for a 91 percent yield is identified as DCTCS as prepared in Example 1.
Analysis by gas-liquid chromatography (GLC) shows the residue to contain 97.5 percent of the afore-mentioned styrene (DCTCS) and less than 2.5 percent of the diene.
26,164-F -10-1. A process for the dehydrohalogenation of a (polyhaloalkyl)arene wherein in the polyhaloalkyl one halogen is a benzylic halogen and at least one halogen is a non-ben~ylic halogen characterized by contacting the (polyhaloalkyl)arene with a catalytic amount of a halide of titanium which has been treated with water and is in neat form or a halide of antimony in neat form in the li~uid phase at temperatures below 100C to form a (haloalkenyl)arene.
PROCESS FOR ~EHYDROHALOGENATING (POLYHALOALI~YL)BENZENES
This invention relates to processes for pre-paring (haloalkenyl)benzenes including (polyhaloalkenyl)-S benzenes.
~ Haloalkyl)styrenes are useful as para~
siticides and insecticides. They are also useful intermediates in the manufacture of other biologically active compounds. Such compounds are conventionally prepared by reacting a halogenated organic compound with an a-methylstyrene in the presence of a free--radical initiator which usually comprises an organic amine and a copper-containing material. These known methods for preparing haloalkenylber.z2nes require long reaction times and undesirably high reaction temperatures and give somewhat low yields of product.
In accordance with the present invention, (haloalkenyl)benzenes and other (haloalkenyl)arenes are advantageously obtained by a dehydrohalogenation process, which comprises contacting a (polyhaloalkyl)arene in which polyhaloalkyl has a benzylic halogen and at least 26,16~-~
~L
ll~B4S5 one non-benzylic aliphatic halogen with a catalytic amount of a halide of titanium which has been treated with water and is in neat form or a halide of antimony in neat form in the liquid phase at temperatures below 100C. Surprisingly, the benzylic halogen of the poly-haloalkyl group is selectively eliminated to form the desired (haloalkenyl)arene while the non-benzylic aliphatic halogen(s) are left undisturbe~. The ~haio-alkenyl)benzenes produced in the practice of this invention are useful as biologically active compounds as described hereinbefore and as intermediates in the preparation of other biologically active compounds.
By a (polyhaloalkyl)arene is meant an aromatic compound in which an aromatic ring bears at least one polyhaloalkyl substituent. In the polyhaloalkyl substi-tuent, one halogen is bonded to the alkyl carbon bonded to the aromatic ring (hereinafter called a benzylic halogen) and at least one halogen is bonded to one other alkyl carbon (hereinafter called a non-benzylic halogen).
By "arene" is meant an aromatic compound having one or more aromatic rings such as benzene, naphthalene, anthracene as well as substituted arenes. The substi-tuents include halo, nitro, alkyl, alkoxy, alkylthio, axyl, aryloxy, sulfo, carboxy, carboxylate ester, --haloalkyl including polyhaloalkyl, haloaryl and other substituent groups that do not interfere with dehydro-halogenation reactions that are catalyzed by Lewis acids. Such substituents are inert in the dehydro-halogenation reactions.
. Preferred (polyhaloalkyl)arenes are repre-sented by Formula I:
26,164-F -2-111~34~i;~ii CH3-C~Y
Ar (R)n wherein Ar is arene, preferably benzene, each R is indi-vidually halo, alkyl, haloalkyl .ncluding pol~haloa'X-Yl Y .
such as -CX3 (e.g., -CF3) and CH3-C-X wherein X and Y
are as defined herein, aryl, haloaryl, nitro, alkoxy, and other inert monovalent organic radicals, X is halo, Y is haloalkyl or substituted haloalkyl wherein alkyl has from 2 to 3 carbons and the non-halogen substituent or substituents may be, for example, nitro or alkoxy, and n is 0 to the maximum number of remaining available ring positions on Ar. Preferably n is from 0 to 2 when Ar is benzene. More preferably, each ~ is individually halo such as Cl, Br, or F; alkyl having 1 to 4 carbons such as -CH3; alkoxy such as -OCH3 and others having 1 to 4 carbons; and -NO2. Most preferably each R is individually Cl, Br or -N02. X is more preferably Cl or Br, most preferably Cl. Y is more preferably halo-alkyl represented by the formula:
-CH2-C-R ' R' wherein X' is Cl or Br, each R' is individually H, halo such as Cl, Br or F, lower alkyl or -NO2. Most preferably Y is -CH2CCl2R' wherein R' is H, Cl, Br, 26,164-F -3--CH3 or -C2H5. For example, Y is most preferably -CH2CC13, -CH2CCl2Br, -CH2CHCl2 and -CH2CH2Cl.
Examples of especially preferred poly(halo-alkyl)arenes include 1,3-dichloro-5-(1,3,3,3-tetra-chloro-1-methylpropyl)benzene, 1,3-dichloro-5-(1,3,3--trichloro-1-methylpropyl)benzene and similar 1,3--dihalo-5-~polyhalobutyl)benzenes. vther prefei-L-ed (polyhaloalkyl)arenes include 3-chloro-1-(1,3,3,3--tetrachloro-l-methylpxopyl)benzene and similar 3-halo-1-(polyhalobutyl)benzenes.
(Polyhaloalkyl)arenes may be prepared by known methods. For example, ~methylstyrene or ar--substituted methylstyrene is reacted with a poly-haloalkane such as carbon tetrachloride, bromotri-chloromethane, methylene chloride or dichloroni-tromethane in the presence of an amine and cuprous chloride to produce a desired (polyhaloalkyl)benzene.
Lewis acids which are suitably employed in the practice of this invention are the Lewis acids which catalyze the elimination of the benzylic halogen from the (polyhaloalkyl)arene via a dehydrohalogenation reaction while essentially all of the non-benzylic halo- -gen substituent(s) of the (polyhaloalkyl)arene remain bonded to the (polyhaloalkyl)arene. Such Lewis acids are stated herein to be suitably active if, during the preferential dehydrohalogenation of essentially all (>95 mole percent) of benzylic halogen of the (poly-haloalkyl)arene, less than lO, preferably less than 5, mole percent of non-benzylic halogen is eliminated.
26,164-F -4-~1184~;5 Examples of Lewis acids which, in neat (undiluted) form, are suitably active include (1) the halides of titanium, preferably TiC14, which have been treated with water and (2) the halides of antimony, preferably antimony pentachloride. of the neat forms, the titanium tetrahalides which have been treated with from 0.1 to 2 moles of water per mole of the titanium tetrahalide are more preferred, with Ti~14 beir,g treated from 0.25 to 1.75 moles of water per mole of TiC14 being most preferred.
In the practice of this invention, the (polyhaloalkyl)arene is contacted with a catalytic amount of a suitably active Lewis acid under dehy-drohalogenation conditions. A catalytic amount is any amount of suitably active Lewis acid which catalyzes the selective dehyd~ohalogenation of the (polyhaloalkyl)arene such that substantially all of the benzylic halogen thereof is eliminated. Advan-tageously, such catalytic amounts are within the range from 0.1 to 20 weight percent of suitably active Lewis acid based on the weight of (polyhalo-alkyl)arene, preferably from 0.1 to 10 weight percent of the Lewis acid, most preferably from 0.2 to 3 weight percent of the Lewis acid.
In addition to the aforementioned starting ingredients, a solvent such as carbon tetrachloride, ethylene dichloride or similar halohydrocarbons is optionally employed. When used, the solvent is present in an amount between 0.5 and 3 liters of solvent per mole of the (polyhaloalkyl)arene.
26,164 F -5-- ~118A~5 While the temperature of the dehydrohalo-genation reaction is not particularly critical, the reaction is advantageously conducted in the liquid phase at a temperature below 100C, preferably between 25C and 80C, and most preferably between 55C and 80C. Preferably, the suitably active Lewis acid catalyst is added to a stirred mixture of the (poly-haloalkyl)arene and the optior.al solvent. It is sometimes desirable to add the (polyhaloalkyl)arene diluted with solvent to a stirred solution of the catalyst in solvent. Thus, the rate of hydrogen halide evolution is controlled by the slow addition of reactant.
After the (polyhaloalkyl)arene is contacted with catalyst, the reac~ion begins immediately, as evidenced by evolution of hydrogen halide gas. The reaction is allowed to proceed to completion while agitating the reaction mixture sufficiently to keep the catalyst in suspension. The reaction pressure is not critical and is conveniently atmospheric.
The product of the dehydrohalogenation reaction is primarily a (polyhaloalkenyl~arene wherein the benzylic halogen and hydrogen on an adjacent carbon are eliminated. In embodiments of particular interest, the (polyhaloalkenyl)arene is represented by formula II:
CH2=C-Y
Ar II
( R) n 26,164-F -6-P~
111~345~i wherein R, Y and n are ~s defined hereinbefore. In preferred embodiments of this invention, the dehydro-halogenation is sufficiently selective such that more than 95 mole percent of benzylic halogen is eliminated, most preferably more than 99 mole percent, and less than 5 mole percent of non-benzylic halogen is elimi-nated most preferably less than 2 mole percent.
The following examples are given to further illustrate the invention. All percentages in the examples are by weight unless otherwise indicated.
Example 1 Preparation of 3,5-dlchloro-~-methylstyrene Chlorine gas is bubbled through 129 g of 3,5-dichlorotoluene in the presence o~ light until no further adsorption occurs. An increase in weight of 83 g results. To the product, weighing 212 g, is added dropwise 400 g of 8 percent fuming sulfuric acid. After being stirred for 30 hours the mixture is poured over cracked ice. The 3,5-dichlorobenzoic acid which precipitated is washed well with water and dried. It weighs 145 g, or 95 percent yield based on the dichlorotoluene. The acid is converted to 3,5-dichlorobenzoyl chloride in 95 percent yield by treating with 125 g thionyl chloride. The chloride, weighing 151 g, is then allowed to react with 150 ml of methyl alcohol and the resulting methyl 3,5-di--chlorobenzoate, which when distilled at 120C-125C
at 7 mm weighs 133 g, or 90 percent of theory. The ester is treated with 2 equivalents of methyl magnesium chloride (125 g), the Grignard complex hydrolyzed, and the product then dehydrated by refluxing with NaHSO4.
26,164-F -7-.
4 ~ 5 The 3,5-dichloro-~-methylstyrene obtained weighs 88 g, or 72 percent of theory based on the ester used, and boiled at 109C-111C at 12 mm. Its specific gravity is 1.196 and its refractive index is 1.5660, both measured at 25C.
Addition of CC14 The 3,5-dichloro-~-methylstyrene is placed in a 250 ml vessel equipped with stirring means and a heating means. A mixture including 18.7 g (0.1 mole) of 3,5-dichloro-~-methylstyrene, as well as 46.2 g (0.3 mole) of CC14 and 0.4 g of cuprous chloride is formed with stirring. To the mixture is added 1.6 g (0.016 mole) of cyclohexylamine. The mixture is heated to the reflux temperature of CC14 and main-tained at reflux temperature until completion of the reaction in 30 minutes. The reaction mixture is cooled and filtered, and the solvent is removed under vacuum leaving 31.2 g (91.5 percent yield) of residual product. This residue is recrystallized from hexane to yield essentially pure 1,3-dichloro--5-(1,3,3,3-tetrachloro-1-methylpropyl)benzene exhibiting a melting point of 44.5-46.5C.
Dehvdrohaloqenation with SbC15 -A mixture composed of a 137 g (0.40 mole) portion of the 1,3-dichloro-5-(1,3,3,3-tetrachloro--l-methylpropyl)benzene (DCTCB) obtained above and 250 ml of CC14 is formed in a 500 ml flask equipped with a stirring and a heating means. With stirring, a 7 g portion (0.023 mole) of SbC15 is added to the flask and dehydrochlorination (as evidenced by HCl gas) to form a crude product mixture occurs at room 26,164-F -8-g temperature. The crude product mixture is heated to reflux (82~C), is held at this temperature for 30 minutes, and is then allowed to cool to a tem-perature near ambient. To the crude product mixture a 150-ml portion of CCl4 is added and then a 200-ml portion of 3N HCl is added with stirring. An aqueous and an organic layer are formed. The organic and a~ueous layers are separated and 200 ml of water is added to the organic layer with stirring. The organic layer is stirred over Na2S04 to remo~e any water remaining. The carbon tetrachloride present in the organic layer is removed under a vacuum leaving 115.8 g of a crude product. Distillation of the crude product yields 100.2 g (0.33 mole) of product containing at least 95 percent of 3,5-dichloro-~-(2,2,2-trichloro-ethyl)styrene (DCTCS) represented by the structure:
H2C=C-CH2-CCl3 Cl ~ Cl and less than 5 percent of diene represented by the structure:
H2C=C-CH=CC12 I
Cl ~ Cl Example 2 Dehydrohaloqenation with H20 Treated TiCl4 A mixture consisting of 5 g (0.0147 mole) of the DCTCB produced according to Example 1, 50 ml of CCl4 and 0.020 ml of water is placed in a 100 ml 26,164-F -9-flask. The mixture is heated to reflux (about 90C) and 0.173 g (0.000911 mole) of TiC14 is added to the mixture. Evolution of HCl is noted as the reflux continues for 2 hours. The mixture is cooled to 45C and 25 ml of concentrated hydrochloric acid is added. An organic layer and an aqueous layer are formed and separated. The organic layer is washed with wateî. The solvent is then removed from the organic layer in vacuum. The remaining residue which weighs 4.0~ g ~0.0133 mole) for a 91 percent yield is identified as DCTCS as prepared in Example 1.
Analysis by gas-liquid chromatography (GLC) shows the residue to contain 97.5 percent of the afore-mentioned styrene (DCTCS) and less than 2.5 percent of the diene.
26,164-F -10-1. A process for the dehydrohalogenation of a (polyhaloalkyl)arene wherein in the polyhaloalkyl one halogen is a benzylic halogen and at least one halogen is a non-ben~ylic halogen characterized by contacting the (polyhaloalkyl)arene with a catalytic amount of a halide of titanium which has been treated with water and is in neat form or a halide of antimony in neat form in the li~uid phase at temperatures below 100C to form a (haloalkenyl)arene.
2. Process of Claim 1 characterized in that the (polyhaloalkyl)arene employed is represented by the formula:
Ar (R)n wherein Ar is arene, each R is individually halo, nitro or an inert monovalent, organic radical, X is halo, Y is haloalkyl or substituted haloalkyl wherein alkyl has 2 or 3 carbons and the non-halogen substi-tuent or substituents are nitro or alkoxy; and n is 0 26,164-F
Ar (R)n wherein Ar is arene, each R is individually halo, nitro or an inert monovalent, organic radical, X is halo, Y is haloalkyl or substituted haloalkyl wherein alkyl has 2 or 3 carbons and the non-halogen substi-tuent or substituents are nitro or alkoxy; and n is 0 26,164-F
Claims
or a whole number from 1 to the maximum number of remaining available ring positions on Ar and the (haloalkenyl)arene is represented by the formula:
in which Y, Ar, R and n are as defined herein.
3. Process of Claim 2 characterized in that each R is individually halo, nitro, alkoxy, alkyl, haloalkyl, aryl or haloaryl, Y is polyhalo-alkyl and n is 0, 1 or 2.
4. Process of Claim 2 characterized in that the (polyhaloalkyl)arene is (polyhaloalkyl)benzene represented by the structural formula:
wherein X is chloro or bromo; R is Cl, Br, F, -NO2, alkyl having 1 to 4 carbons, or alkoxy having 1 to 4 carbons; Y is haloalkyl represented by the formula:
26,164-F
wherein X' is Cl or Br, each R' is individually H, Cl or Br; and n is 0 to 2.
5. Process of Claim 3 characterized in that the Lewis acid is SbCl5 or TiCl4 combined with from 0.25 to 1.75 moles of water per mole of TiCl4.
6. Process of Claim 5 characterized in that the (polyhaloalkyl)benzene is 1,3-dichloro-5--(1,3,3,3-tetrachloro-1-methylpropyl)benzene and the dehydrohalogenation is carried out in the presence of from 1.5 to 5 weight percent of TiCl4 based on (polyhaloalkyl)benzene and from 0.25 to 1.75 moles of water per mole of TiCl4 at a reaction temperature in the range from 25° to 80°C.
26,164-F
in which Y, Ar, R and n are as defined herein.
3. Process of Claim 2 characterized in that each R is individually halo, nitro, alkoxy, alkyl, haloalkyl, aryl or haloaryl, Y is polyhalo-alkyl and n is 0, 1 or 2.
4. Process of Claim 2 characterized in that the (polyhaloalkyl)arene is (polyhaloalkyl)benzene represented by the structural formula:
wherein X is chloro or bromo; R is Cl, Br, F, -NO2, alkyl having 1 to 4 carbons, or alkoxy having 1 to 4 carbons; Y is haloalkyl represented by the formula:
26,164-F
wherein X' is Cl or Br, each R' is individually H, Cl or Br; and n is 0 to 2.
5. Process of Claim 3 characterized in that the Lewis acid is SbCl5 or TiCl4 combined with from 0.25 to 1.75 moles of water per mole of TiCl4.
6. Process of Claim 5 characterized in that the (polyhaloalkyl)benzene is 1,3-dichloro-5--(1,3,3,3-tetrachloro-1-methylpropyl)benzene and the dehydrohalogenation is carried out in the presence of from 1.5 to 5 weight percent of TiCl4 based on (polyhaloalkyl)benzene and from 0.25 to 1.75 moles of water per mole of TiCl4 at a reaction temperature in the range from 25° to 80°C.
26,164-F
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000336836A CA1118455A (en) | 1979-10-02 | 1979-10-02 | Dehydrohalogenation of (polyhaloalkyl) benzenes |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000336836A CA1118455A (en) | 1979-10-02 | 1979-10-02 | Dehydrohalogenation of (polyhaloalkyl) benzenes |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1118455A true CA1118455A (en) | 1982-02-16 |
Family
ID=4115265
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000336836A Expired CA1118455A (en) | 1979-10-02 | 1979-10-02 | Dehydrohalogenation of (polyhaloalkyl) benzenes |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1118455A (en) |
-
1979
- 1979-10-02 CA CA000336836A patent/CA1118455A/en not_active Expired
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