WO2000037400A1 - Halogenation in ionic liquids - Google Patents

Halogenation in ionic liquids Download PDF

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Publication number
WO2000037400A1
WO2000037400A1 PCT/GB1999/003908 GB9903908W WO0037400A1 WO 2000037400 A1 WO2000037400 A1 WO 2000037400A1 GB 9903908 W GB9903908 W GB 9903908W WO 0037400 A1 WO0037400 A1 WO 0037400A1
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chlorinated
ionic liquid
cation
alkyl
salt
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PCT/GB1999/003908
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French (fr)
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Neil Winterton
Kenneth Richard Seddon
Yasmin Patell
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Ineos Chlor Limited
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Priority to AU12842/00A priority Critical patent/AU1284200A/en
Publication of WO2000037400A1 publication Critical patent/WO2000037400A1/en

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J31/00—Catalysts comprising hydrides, coordination complexes or organic compounds
    • B01J31/26—Catalysts comprising hydrides, coordination complexes or organic compounds containing in addition, inorganic metal compounds not provided for in groups B01J31/02 - B01J31/24
    • B01J31/28—Catalysts comprising hydrides, coordination complexes or organic compounds containing in addition, inorganic metal compounds not provided for in groups B01J31/02 - B01J31/24 of the platinum group metals, iron group metals or copper
    • B01J31/30—Halides
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J31/00—Catalysts comprising hydrides, coordination complexes or organic compounds
    • B01J31/02—Catalysts comprising hydrides, coordination complexes or organic compounds containing organic compounds or metal hydrides
    • B01J31/0231—Halogen-containing compounds
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J31/00—Catalysts comprising hydrides, coordination complexes or organic compounds
    • B01J31/02—Catalysts comprising hydrides, coordination complexes or organic compounds containing organic compounds or metal hydrides
    • B01J31/0277—Catalysts comprising hydrides, coordination complexes or organic compounds containing organic compounds or metal hydrides comprising ionic liquids, as components in catalyst systems or catalysts per se, the ionic liquid compounds being used in the molten state at the respective reaction temperature
    • B01J31/0278—Catalysts comprising hydrides, coordination complexes or organic compounds containing organic compounds or metal hydrides comprising ionic liquids, as components in catalyst systems or catalysts per se, the ionic liquid compounds being used in the molten state at the respective reaction temperature containing nitrogen as cationic centre
    • B01J31/0281—Catalysts comprising hydrides, coordination complexes or organic compounds containing organic compounds or metal hydrides comprising ionic liquids, as components in catalyst systems or catalysts per se, the ionic liquid compounds being used in the molten state at the respective reaction temperature containing nitrogen as cationic centre the nitrogen being a ring member
    • B01J31/0284—Catalysts comprising hydrides, coordination complexes or organic compounds containing organic compounds or metal hydrides comprising ionic liquids, as components in catalyst systems or catalysts per se, the ionic liquid compounds being used in the molten state at the respective reaction temperature containing nitrogen as cationic centre the nitrogen being a ring member of an aromatic ring, e.g. pyridinium
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J31/00—Catalysts comprising hydrides, coordination complexes or organic compounds
    • B01J31/02—Catalysts comprising hydrides, coordination complexes or organic compounds containing organic compounds or metal hydrides
    • B01J31/0277—Catalysts comprising hydrides, coordination complexes or organic compounds containing organic compounds or metal hydrides comprising ionic liquids, as components in catalyst systems or catalysts per se, the ionic liquid compounds being used in the molten state at the respective reaction temperature
    • B01J31/0287—Catalysts comprising hydrides, coordination complexes or organic compounds containing organic compounds or metal hydrides comprising ionic liquids, as components in catalyst systems or catalysts per se, the ionic liquid compounds being used in the molten state at the respective reaction temperature containing atoms other than nitrogen as cationic centre
    • B01J31/0288—Phosphorus
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J31/00—Catalysts comprising hydrides, coordination complexes or organic compounds
    • B01J31/02—Catalysts comprising hydrides, coordination complexes or organic compounds containing organic compounds or metal hydrides
    • B01J31/0277—Catalysts comprising hydrides, coordination complexes or organic compounds containing organic compounds or metal hydrides comprising ionic liquids, as components in catalyst systems or catalysts per se, the ionic liquid compounds being used in the molten state at the respective reaction temperature
    • B01J31/0287—Catalysts comprising hydrides, coordination complexes or organic compounds containing organic compounds or metal hydrides comprising ionic liquids, as components in catalyst systems or catalysts per se, the ionic liquid compounds being used in the molten state at the respective reaction temperature containing atoms other than nitrogen as cationic centre
    • B01J31/0289—Sulfur
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J31/00—Catalysts comprising hydrides, coordination complexes or organic compounds
    • B01J31/02—Catalysts comprising hydrides, coordination complexes or organic compounds containing organic compounds or metal hydrides
    • B01J31/0277—Catalysts comprising hydrides, coordination complexes or organic compounds containing organic compounds or metal hydrides comprising ionic liquids, as components in catalyst systems or catalysts per se, the ionic liquid compounds being used in the molten state at the respective reaction temperature
    • B01J31/0287—Catalysts comprising hydrides, coordination complexes or organic compounds containing organic compounds or metal hydrides comprising ionic liquids, as components in catalyst systems or catalysts per se, the ionic liquid compounds being used in the molten state at the respective reaction temperature containing atoms other than nitrogen as cationic centre
    • B01J31/0291—Catalysts comprising hydrides, coordination complexes or organic compounds containing organic compounds or metal hydrides comprising ionic liquids, as components in catalyst systems or catalysts per se, the ionic liquid compounds being used in the molten state at the respective reaction temperature containing atoms other than nitrogen as cationic centre also containing elements or functional groups covered by B01J31/0201 - B01J31/0274
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J31/00—Catalysts comprising hydrides, coordination complexes or organic compounds
    • B01J31/26—Catalysts comprising hydrides, coordination complexes or organic compounds containing in addition, inorganic metal compounds not provided for in groups B01J31/02 - B01J31/24
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07B—GENERAL METHODS OF ORGANIC CHEMISTRY; APPARATUS THEREFOR
    • C07B39/00—Halogenation
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C17/00—Preparation of halogenated hydrocarbons
    • C07C17/013—Preparation of halogenated hydrocarbons by addition of halogens
    • C07C17/02—Preparation of halogenated hydrocarbons by addition of halogens to unsaturated hydrocarbons
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07D—HETEROCYCLIC COMPOUNDS
    • C07D233/00—Heterocyclic compounds containing 1,3-diazole or hydrogenated 1,3-diazole rings, not condensed with other rings
    • C07D233/54—Heterocyclic compounds containing 1,3-diazole or hydrogenated 1,3-diazole rings, not condensed with other rings having two double bonds between ring members or between ring members and non-ring members
    • C07D233/66—Heterocyclic compounds containing 1,3-diazole or hydrogenated 1,3-diazole rings, not condensed with other rings having two double bonds between ring members or between ring members and non-ring members with hetero atoms or with carbon atoms having three bonds to hetero atoms with at the most one bond to halogen, e.g. ester or nitrile radicals, directly attached to ring carbon atoms
    • C07D233/68—Halogen atoms
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2231/00—Catalytic reactions performed with catalysts classified in B01J31/00
    • B01J2231/30—Addition reactions at carbon centres, i.e. to either C-C or C-X multiple bonds
    • B01J2231/32—Addition reactions to C=C or C-C triple bonds
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J27/00—Catalysts comprising the elements or compounds of halogens, sulfur, selenium, tellurium, phosphorus or nitrogen; Catalysts comprising carbon compounds
    • B01J27/06—Halogens; Compounds thereof
    • B01J27/08—Halides
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J27/00—Catalysts comprising the elements or compounds of halogens, sulfur, selenium, tellurium, phosphorus or nitrogen; Catalysts comprising carbon compounds
    • B01J27/06—Halogens; Compounds thereof
    • B01J27/08—Halides
    • B01J27/10—Chlorides

Definitions

  • the present invention relates to a process for the halogenation of organic compounds, particularly to a process for the chlorination of alkenes and alkynes using elemental chlorine and more particularly to a process for the production of ethylene dichloride, to chlorinated ionic liquids for use in the process and to methods for the preparation thereof.
  • halogenation we mean chlorination, bromination and bromochlorination.
  • Ethylene dichloride also known as 1,2-dichloroethane
  • EDC 1,2-dichloroethane
  • the desired product of the chlorination reaction has to be separated from by-products, both organic and inorganic, and from catalysts and inhibitors, designed respectively to facilitate the addition and inhibit the substitution reactions.
  • separation is effected, for example, by distillation or washing.
  • ionic liquid we mean a polar, aprotic, electrically-conductive composition which is liquid and homogeneous under ambient conditions, or which becomes liquid and homogeneous just above ambient temperature, eg below 100°C, which consists entirely of ions, which has negligible vapour pressure, a wide electrochemical “window” and very high solvation capacity and which dissolves a broad range of organic and inorganic substances.
  • ambient temperature eg below 100°C
  • the ionic liquid has a melting point above ambient temperature it will be appreciated that the practical utility of such materials will depend on the ease with which chemical processing can be carried out therein and liquid recovery effected therefrom at these temperatures.
  • ionic liquids to catalyse hydrocarbon conversion reactions, eg polymerisation or oligomerisation of olefins, and alkylation reactions
  • the ionic liquids are preferably 1-(C M alkyl)-3-(C 6 -C 30 alkyl) imidazolium chlorides, particularly l-methyl-3-C I0 alkyl-imidazolium chloride, or 1-hydrocarbyl pyridinium halides wherein the hydrocarbyl group is for example ethyl, butyl or other alkyl is described in WO 95/21871, WO 95/21872 and WO 95/21806.
  • ionic liquids in the recovery of nuclear waste is described in WO 95/21871, WO 95/21872 and WO 95/21806.
  • Ionic liquids which comprise at least one alkylaluminium dihalide and at least one quaternary ammonium halide and/or one quaternary phosphonium halide and the use thereof as solvents in catalytic reactions are described in US 5,104,840.
  • chlorometallate compounds and salts are known to be useful as catalysts in the chlorination of alkenes, particularly ethylene.
  • an iron compound eg ferric chloride or sodium tetrachloroferrate
  • chloroaluminates and recently N-alkyl pyridinium chloroaluminate, as such chlorination catalysts has also been reported in WO 97/33849.
  • the use of a chlorine-containing pyridinium tetrachloroferrate as a catalyst for the chlorination of ethylene has been described in RU 2035446.
  • the compound is a crystalline solid at ambient temperature. Accordingly, it cannot act as a reaction medium and it is not an ionic liquid as hereindefined.
  • selective chlorination of olefins is facilitated in the aforementioned ionic liquids, and particularly in chlorinated ionic liquids.
  • selective chlorination we mean a process wherein the proportion of additive chlorination is enhanced and the proportion of substitutive chlorination is suppressed. For example, in the reaction of chlorine with ethylene there is less tendency for formation of ⁇ -Tri to occur.
  • the halogen used in the process according to the first aspect of the present invention is preferably chlorine.
  • the hydrocarbon to be halogenated in the process according to the first aspect of the present invention is a C, . , 5 terminal or internal monoolefin, diolefin or polyolefin, preferably ethylene, propylene or butylene; a C, .15 alkenyl-substituted aromatic, eg styrene; or an alkyne, eg acetylene and methylacetylene. It will be appreciated that to facilitate product recovery from the process, and hence avoid excessive contact of the desired product with chlorine, the product will be sufficiently volatile to be readily removed from the ionic liquid.
  • the hydrocarbon to be halogenated in the process according to the first aspect of the present invention may bear substituents which do not unduly inhibit the desired chlorination reaction such as those which do not readily interact with the ionic or chlorinated ionic liquid, particularly in the case of chlorometallate ionic liquids do not co-ordinate to the metal, eg halogen, dialkylamino, nitro groups and related groups readily identified by those skilled in the art.
  • the ionic liquid acts as both catalyst for the additive chlorination of the starting material and inhibitor for the substitutive chlorination of the desired reaction product as well as a convenient medium in which the reaction can occur and from which the products can be readily separated.
  • ionic liquids which may be used in the processes according to the first and second aspects of the present invention may be mentioned inter alia the unitary ionic liquids described in WO 95/21871, the binary ionic liquids described in US 5,104,840 and the ternary ionic liquids described in WO 95/21872.
  • Ionic liquids comprise mixtures of at least one suitable anion and at least one suitable cation.
  • suitable cations of which the ionic liquids used in the processes according to the present invention are comprised may be mentioned inter alia large, bulky, unsymmetrical cations of organic salts derived from an amine, phosphine or sulphide, ie a quaternary ammonium ([R 4 N]X), quaternary phosphonium ([R 4 P]X) or tertiary sulphonium ([R 3 S]X) salts.
  • the hydrocarbyl groups R which may be the same or different, are C,_ 20 aliphatic (saturated or unsaturated) or aromatic.
  • the hydrocarbyl groups form a cyclic group with N, more preferably they form a 1,3-dihydrocarbylimidazolium cation or N-hydrocarbylpyridinium cation wherein the hydrocarbyl substituents are preferably C, .18 -alkyl groups, more preferably C, .8 -alkyl groups and more particularly preferably C, .4 -alkyl groups.
  • the cation in the quaternary ammonium salt comprises a
  • 1,3-dihydrocarbylimidazolium at least one of the hydrocarbyl groups is preferably methyl, eg 1,3-dimethylimidazolium.
  • N-alkylpyridinium cations may be mentioned ter alia N-sec-butylpyridinium or preferably N-n-butylpyridinium.
  • quaternary phosphonium salts wherein the hydrocarbyl groups R 2 , which may be the same or different, are C 2 aliphatic (saturated or unsaturated) or aromatic may be mentioned inter alia tetrabutylphosphonium chloride and tetraphenyl phosphonium chloride.
  • tertiary sulphonium salts [R 3 3 S]X) wherein the hydrocarbyl groups R 3 , which may be the same or different, are C, .12 aliphatic (saturated or unsaturated) or aromatic may be mentioned inter alia trimethylsulphonium chloride and trimethylsulphonium bromide.
  • cation of a quaternary ammonium salt chlorination of certain of those cations may occur in the processes according to the first or second aspects of the present invention.
  • chlorination of l-ethyl-3-methylimidazolium (emim + ) chloroaluminate gives sequentially 4-chloro-, 5-chloro-, 4,5-dichloro- and 2,4,5-trichloro- 1 -ethyl-3-methylimidazolium chloroaluminate; chlorination of a l-n-butyl-3-methylimidazolium (bmim + ) chloroaluminate liquid gives 4-chloro- 1 -n-butyl-3-methylimidazolium chloroaluminate, 5-chloro- 1 -n-butyl-3-methylimidazolium chloroaluminate, 4,5-dichloro-l-n-butyl-3-methylimidazolium chloroaluminate and 2,4,5-trichloro- l-n-butyl-3-methylimidazolium chloroaluminate; and chlorination of l-
  • a chlorinated ionic liquid comprising a mixture of at least one suitable anion and at least one suitable cation containing covalently-bonded chlorine.
  • the chlorinated ionic liquid according to the present invention comprises at least one suitable anion as hereinafter defined and at least one suitable chlorinated cation which is preferably the cation of a chlorinated quaternary ammonium salt, more preferably a chlorinated quaternary ammonium salt ([R 4 N]X) wherein the hydrocarbyl groups R 4 form a cyclic group with N and particularly more preferably a chlorinated 1,3-dialkylimidazolium salt.
  • Chlorinated ionic liquids according to the present invention tend to have higher viscosities and higher mp's than the corresponding ionic liquid.
  • the at least one suitable cation in the chlorinated ionic liquid according to the further aspect of the present invention is an imidazolium salt
  • the imidazolium cation may be mono-chlorinated, eg 4-chloro- l-alkyl-3-methylimidazolium chloride, 4-chloro- 1 -alkyl-2,3-dimethylimidazolium chloride, 5-chloro- 1 -alkyl-3-methylimidazolium chloride, 5-chloro-l-alkyl-2,3-dimethylimidazolium chloride; di-chlorinated, eg 4,5-dichloro-l-alkyl-3-methylimidazolium chloride, 4,5-dichloro-l-alkyl-2,3-dimethylimidazolium chloride; or
  • the chlorinated ionic liquid according to the present invention may be prepared by chlorination of a non-chlorinated ionic liquid as hereinbefore defined or alternatively the chlorinated cationic species can be prepared independently and converted into the chlorinated ionic liquid by appropriate reactions well known to those skilled in the art.
  • 5-chloro- 1,3-dimethylimidazo Hum chloride may be prepared by the process described by Collinse et al in J. Amer. Chem. Soc, 76, 3653 (1954)
  • 2,4,5-trichloro- 1,3-dimethylimidazolium chloride may be prepared by the process described by Janousek et al in Angew. Chem. Int. Edn., 18, 616, (1979).
  • chlorinated cations have been synthesised as chloride salts by literature routes. They may be converted to ionic liquids by treatment with suitable anionic species, for example by treatment with appropriate amounts of aluminium chloride. According to a yet further aspect of the present invention there is provided a method for the preparation of a chlorinated ionic liquid by chlorination of a non-chlorinated ionic liquid or by conversion of a chlorinated cationic species into the chlorinated ionic liquid by treatment with suitable anionic species.
  • chlorinated l-ethyl-3-ethylimidazolium-based ionic liquids retain their liquid properties and, accordingly, are useful as ionic liquids in the processes according to the first and second aspects of the present invention.
  • the preferred cations of which the ionic liquids used in the first or second aspects of the present invention are comprised are those which surprisingly suppress substitutive chlorination, for example suppress the formation of ⁇ -Tri in the reaction of chlorine with ethylene.
  • Such preferred cations include the chlorinated and unchlorinated 1,3-dialkylimidazolium species.
  • suitable anions may be mentioned inter alia fluorophosphates PF 6 " , fluoroborates BF 4 " , carboxylates, eg CH 3 CO 2 " , fluorosulfonates, eg CF 3 SO 3 " , fluoroalkylsulfonamides, eg (CF 3 SO 2 ),N “ , nitrate NO 3 " , trichloride Cl 3 " , or preferably anions derived from a metal halide, which are known in the art as halometallates.
  • Suitable metals of which the aforementioned halometallates may be comprised may be mentioned mter alia gallium, indium, iron, copper, zinc or preferably aluminium.
  • the halide is preferably chloride or bromide, more preferably chloride although we do not exclude the possibility that it may be fluoride or iodide.
  • chlorometallates may exist as mixtures involving neutral metal halide, mononuclear, dinuclear and oligonuclear anions involved in acid-base equilibria.
  • complex chlorometallates may be mentioned chloroaluminates, A1C1 3 /A1C1 4 ⁇ chloroferrates, FeCl 3 /FeCl 4 " , chlorocuprates CuCl 2 /CuCl 3 VCuCl 4 2" and chlorozincates ZnCl 2 /ZnCl 3 7ZnCl 4 2" and mixtures thereof.
  • the mixture may comprise one or more anions which may be involved with such acid-base equilibria and/or one or more of, for example, fluorophosphate PF 6 " , fluoroborate BF 4 " , carboxylate, eg acetate CH 3 CO 2 " , fluorosulphonate CF 3 SO 3 " , fluoroalkylsulfonamides, eg (CF 3 SO 2 ) 2 N ⁇ nitrate NO 3 " , and trichloride Cl 3 " .
  • the composition is chosen such that (i) a liquid phase is obtained under ambient conditions, preferably with as wide a liquid range as possible and (ii) the desired Lewis acidity/basicity of the liquid is obtained.
  • the acidity/basicity is determined by the molar ratio of metal halide to halide ion, with the halide ion being provided in the form of the halide salt of the desired cation.
  • the ionic liquid in ionic liquids derived from an aluminium halide, where the molar ratio of aluminium halide to organic salt is greater than 1, ie excess aluminium halide, the ionic liquid will be acidic, eg at 67 mole % aluminium halide the ionic liquid comprises A1C1 4 " and A1 2 C1 7 " , and that where the molar ratio of aluminium halide to organic salt is less than 1, ie excess organic salt, the ionic liquid will be basic, eg at 40 mole % aluminium halide the ionic liquid comprises Cl " and A1C1 4 " .
  • mixtures of l-ethyl-3-methylimidazolium chloride/aluminium chloride containing 40-67% aluminium chloride are liquid at 25°C thereby providing a chlorination catalyst/inhibitor combination and a reaction medium in which chlorination of ethylene and the ready separation of products can be effected.
  • the components of the ionic liquid can be mixed in any order as disclosed in US 5,104,840, the disclosure in which is incorporated herein by way of reference.
  • the neat components may be mixed.
  • the metal halide may be dissolved in an aliphatic solvent to form a solution which is mixed with the organic salt to obtain two liquid phases and the aliphatic solvent, typically the supernatant phase, is removed.
  • the anion in the ionic liquid used in the processes according to the first or second aspects of the present invention is, for example, trifluoromethanesulfonate or tetrafluoroborate
  • the ionic liquid may be obtained by methods described in the literature.
  • l-ethyl-3-ethylimidazolium trifluoromethanesulfonate may be synthesised by the method described by Bonhote et al, Inorganic Chemistry, 1996, Vol.35, pi 176 by adding methyl trifluoromethanesulfonate in an argon atmosphere dropwise to 1-ethylimidazole in pure, dry 1,1,1-trichloroethane followed by reflux for 2 hours.
  • At least one of the anions is preferably derived from an aluminium or ferric halide group and the cation is preferably a quaternary ammonium salt.
  • halogenation reactions which may be carried out by the process according to the first aspect of the present invention may be mentioned inter alia conversion of ethylene into EDC, propylene into 1,2-dichloropropene, cyclohexene into 1 ,2-dichloro-cyclohexane and but-2-yne into 2,3-dichloro-2-butene.
  • Example 1 The present invention is further illustrated by reference to the following Examples.
  • Example 1 The present invention is further illustrated by reference to the following Examples.
  • This Example illustrates the preparation of chlorinated ionic liquids according to the present invention.
  • Chlorine gas at 298K was bubbled through an acidic chloroaluminate ionic liquid prepared by mixing l-ethyl-3-methylimidazolium chloride and aluminium trichloride in molar ratio 1 :2. After 5 minutes, the nuclear magnetic resonance spectrum of the ionic liquid indicated the formation of 28% of a mixture of 4-chloro- 1 -ethy 1-3 -methy limidazolium cation and
  • Chloroaluminate ionic liquid (67 % acidic; 20 ml), prepared by mixing an imidazolium chloride and aluminium trichloride in molar ratio 1 :2 was placed in a schlenk tube with a magnetic stirrer and chlorine gas was bubbled through the ionic liquid at room temperature until analysis by ⁇ and 13 C NMR spectroscopy indicated that chlorination was complete.
  • Example 2 Chlorine gas and ethylene were bubbled through 4,5-dichloro-l-ethyl-3-methylimidazolium tetrachloroaluminate prepared in Example 2 (67 % acidic; 3 ml) at room temperature (except Example 7 which was carried out at -18°C), in daylight (except Example 9 which was carried out in the dark), for 15 minutes. An exotherm and an increase in the volume of the reaction mixture were observed. The product was distilled out of the reaction mixture at room temperature and analysed by ⁇ NMR and gas chromatography. The results are shown in Table 2.
  • Example 10 the reaction product was found to comprise 1,1,2-trichloroethane, 1,1,2,2-tetrachloroethane, 1,1,1,2,2-pentachloroethane and hexachloroethane as well as EDC.
  • Example 10 the reaction product was found to comprise 1,1,2-trichloroethane, 1,1,2,2-tetrachloroethane, 1,1,1,2,2-pentachloroethane and hexachloroethane as well as EDC.
  • This Example illustrates the preparation of EDC by the process according to the present invention in a basic chloroaluminate.
  • Chlorine gas (30 ml/min) and ethylene (30 ml min) were bubbled through l-ethyl-3-methylimidazolium tetrachloroaluminate (40 % basic; 3 ml) at room temperature in daylight for 15 minutes. An exotherm (approx. 35°C) and an increase in the volume of the reaction mixture (appox. 1 ml) were observed.
  • This Example illustrates the preparation of EDC by the process according to the present invention in an unchlorinated ionic liquid.
  • Example 10 was repeated except that l-n-butyl-3-methylimidazolium hexafluorophosphate, prepared by the process of Suarez et al, J. Chim. Phys., 95, 1626 (1998), was used instead of l-ethyl-3-methylimidazolium tetrachloroaluminate. An exotherm (approx. 35°C) and an increase in the volume of the reaction mixture (appox. 0.5 ml) were observed.
  • the product was distilled out of the reaction mixture at room temperature and characterised as EDC by ⁇ NMR spectroscopy (acetone d6; 300MHz;298°K): ⁇ /p.p.m. 3.73(s, 4H, C 2 H 4 C1 2 ).

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Abstract

A process for the halogenation of unsaturated hydrocarbons by reacting with chlorine and/or bromine in an ionic liquid. A process for the preparation of ethylene dichloride. Chlorinated ionic liquids comprising a mixture of at least one anion and at least one cation containing covalently-bonded chlorine and a method for the preparation thereof.

Description

HALOGENATION IN IONIC LIQUIDS
The present invention relates to a process for the halogenation of organic compounds, particularly to a process for the chlorination of alkenes and alkynes using elemental chlorine and more particularly to a process for the production of ethylene dichloride, to chlorinated ionic liquids for use in the process and to methods for the preparation thereof.
By halogenation we mean chlorination, bromination and bromochlorination.
For convenience the invention will hereinafter be described by reference to chlorination. Ethylene dichloride, also known as 1,2-dichloroethane, will hereinafter be referred to for convenience as "EDC".
In the chlorination of olefins there is a tendency for over-chlorination to occur wherein substitutive chlorination of the desired product competes with additive chlorination of the starting material to produce chlorinated organic by-products and hydrogen chloride. For example, in the production of EDC by the chlorination of ethylene with elemental chlorine under known production conditions there is a tendency for over-chlorination to occur to produce CH2C1-CHC12, known in the art as β-Tri, and other more highly chlorinated by-products. It will be appreciated that in other alkenes, eg propene, there are further sites at which substitutive chlorination can occur. Furthermore, the presence of oxygen in the chlorine and adventitious water in the starting materials will cause further minor by-product formation.
The desired product of the chlorination reaction has to be separated from by-products, both organic and inorganic, and from catalysts and inhibitors, designed respectively to facilitate the addition and inhibit the substitution reactions. Such separation is effected, for example, by distillation or washing.
There is a continuing need in the chemical industry, particularly in the chlorchemical industry, to avoid waste and to reduce the number of processing stages by avoiding additional purification steps, with the associated capital requirements and energy usage. Recently the development of a certain class of liquids, known in the art as ionic liquids, has been reported.
By "ionic liquid" we mean a polar, aprotic, electrically-conductive composition which is liquid and homogeneous under ambient conditions, or which becomes liquid and homogeneous just above ambient temperature, eg below 100°C, which consists entirely of ions, which has negligible vapour pressure, a wide electrochemical "window" and very high solvation capacity and which dissolves a broad range of organic and inorganic substances. Where the ionic liquid has a melting point above ambient temperature it will be appreciated that the practical utility of such materials will depend on the ease with which chemical processing can be carried out therein and liquid recovery effected therefrom at these temperatures.
The use of ionic liquids as reaction media for the dimerisation and oligomerisation of olefins in the presence of a nickel complex, eg NiCl2,2PBu3, has been reported. For example, the preparation of iso-octene by the dimerisation of n-butene and the oligomerisation of propylene has been described in EP 0,488,073 and US 5,104,840 respectively.
The use of ionic liquids to catalyse hydrocarbon conversion reactions, eg polymerisation or oligomerisation of olefins, and alkylation reactions wherein the ionic liquids are preferably 1-(CM alkyl)-3-(C6-C30 alkyl) imidazolium chlorides, particularly l-methyl-3-CI0alkyl-imidazolium chloride, or 1-hydrocarbyl pyridinium halides wherein the hydrocarbyl group is for example ethyl, butyl or other alkyl is described in WO 95/21871, WO 95/21872 and WO 95/21806. The use of ionic liquids in the recovery of nuclear waste is described in WO
96/32729 and WO 98/06106.
The use of ionic liquids as catalysts in the preparation of linear alkylbenzenes is described in WO 98/03454.
The use of ionic liquids in processes for the preparation of branched fatty acids from straight-chain fatty-acids is described in WO 98/07679 and WO 98/07680.
Ionic liquids which comprise at least one alkylaluminium dihalide and at least one quaternary ammonium halide and/or one quaternary phosphonium halide and the use thereof as solvents in catalytic reactions are described in US 5,104,840.
Certain chlorometallate compounds and salts are known to be useful as catalysts in the chlorination of alkenes, particularly ethylene. Typically, an iron compound, eg ferric chloride or sodium tetrachloroferrate, is used as such a chlorometallate catalyst. The use of chloroaluminates, and recently N-alkyl pyridinium chloroaluminate, as such chlorination catalysts has also been reported in WO 97/33849. The use of a chlorine-containing pyridinium tetrachloroferrate as a catalyst for the chlorination of ethylene has been described in RU 2035446. However, the compound is a crystalline solid at ambient temperature. Accordingly, it cannot act as a reaction medium and it is not an ionic liquid as hereindefined.
We have found surprisingly that selective chlorination of olefins is facilitated in the aforementioned ionic liquids, and particularly in chlorinated ionic liquids. By selective chlorination we mean a process wherein the proportion of additive chlorination is enhanced and the proportion of substitutive chlorination is suppressed. For example, in the reaction of chlorine with ethylene there is less tendency for formation of β-Tri to occur.
According to the first aspect of the present invention there is provided a process for the halogenation of a hydrocarbon wherein the hydrocarbon is reacted with a halogen characterised in that the reaction is carried out in an ionic liquid.
The halogen used in the process according to the first aspect of the present invention is preferably chlorine.
The hydrocarbon to be halogenated in the process according to the first aspect of the present invention is a C,.,5 terminal or internal monoolefin, diolefin or polyolefin, preferably ethylene, propylene or butylene; a C,.15 alkenyl-substituted aromatic, eg styrene; or an alkyne, eg acetylene and methylacetylene. It will be appreciated that to facilitate product recovery from the process, and hence avoid excessive contact of the desired product with chlorine, the product will be sufficiently volatile to be readily removed from the ionic liquid.
The hydrocarbon to be halogenated in the process according to the first aspect of the present invention may bear substituents which do not unduly inhibit the desired chlorination reaction such as those which do not readily interact with the ionic or chlorinated ionic liquid, particularly in the case of chlorometallate ionic liquids do not co-ordinate to the metal, eg halogen, dialkylamino, nitro groups and related groups readily identified by those skilled in the art.
According to the second aspect of the present invention there is provided a process for the preparation of EDC which comprises reacting ethylene with elemental chlorine in an ionic liquid. Surprisingly, we have found that chlorination of the hydrocarbon occurs readily in the processes according to the first and second aspects of the present invention and the products of the chlorination reaction may be readily separated from the ionic liquid.
In a preferred embodiment of the present invention it is believed that the ionic liquid acts as both catalyst for the additive chlorination of the starting material and inhibitor for the substitutive chlorination of the desired reaction product as well as a convenient medium in which the reaction can occur and from which the products can be readily separated.
As examples of ionic liquids which may be used in the processes according to the first and second aspects of the present invention may be mentioned inter alia the unitary ionic liquids described in WO 95/21871, the binary ionic liquids described in US 5,104,840 and the ternary ionic liquids described in WO 95/21872. The disclosures in which patent specifications are incorporated herein by way of reference.
For convenience, the ionic liquid used in the processes according to the present invention will hereinafter be described by reference to a binary system.
Ionic liquids comprise mixtures of at least one suitable anion and at least one suitable cation.
As examples of suitable cations of which the ionic liquids used in the processes according to the present invention are comprised may be mentioned inter alia large, bulky, unsymmetrical cations of organic salts derived from an amine, phosphine or sulphide, ie a quaternary ammonium ([R4N]X), quaternary phosphonium ([R4P]X) or tertiary sulphonium ([R3S]X) salts.
Where the suitable cation is the cation of a quaternary ammonium salt ([R4N]X) the hydrocarbyl groups R, which may be the same or different, are C,_20 aliphatic (saturated or unsaturated) or aromatic. Preferably the hydrocarbyl groups form a cyclic group with N, more preferably they form a 1,3-dihydrocarbylimidazolium cation or N-hydrocarbylpyridinium cation wherein the hydrocarbyl substituents are preferably C,.18-alkyl groups, more preferably C,.8-alkyl groups and more particularly preferably C,.4-alkyl groups. Where the cation in the quaternary ammonium salt comprises a
1,3-dihydrocarbylimidazolium at least one of the hydrocarbyl groups is preferably methyl, eg 1,3-dimethylimidazolium. As examples of N-alkylpyridinium cations may be mentioned ter alia N-sec-butylpyridinium or preferably N-n-butylpyridinium.
As examples of the aforementioned quaternary ammonium salts ([R4N]X) wherein the hydrocarbyl groups are aromatic groups or C,.20 aliphatic groups which do not form a cyclic group may be mentioned trimethylphenylammonium chloride.
As examples of the aforementioned quaternary phosphonium salts ([R2 4P]X) wherein the hydrocarbyl groups R2, which may be the same or different, are C 2 aliphatic (saturated or unsaturated) or aromatic may be mentioned inter alia tetrabutylphosphonium chloride and tetraphenyl phosphonium chloride. As examples of the aforementioned tertiary sulphonium salts ([R3 3S]X) wherein the hydrocarbyl groups R3, which may be the same or different, are C,.12 aliphatic (saturated or unsaturated) or aromatic may be mentioned inter alia trimethylsulphonium chloride and trimethylsulphonium bromide.
We have found that where the suitable cation is the cation of a quaternary ammonium salt chlorination of certain of those cations may occur in the processes according to the first or second aspects of the present invention.
We have found that where acidic ionic liquids based on imidazolium cations are treated with chlorine the cations are fully chlorinated at the C(4) and C(5) positions of the imidazolium ring and likewise that where basic ionic liquids based on imidazolium cations are treated with chlorine the cations are fully chlorinated at the C(4) and C(5) positions of the imidazolium ring albeit at a slower rate. Acidic ionic chlorides and basic ionic chlorides are more fully described hereinafter.
For example, we have found that chlorination of l-ethyl-3-methylimidazolium (emim+) chloroaluminate gives sequentially 4-chloro-, 5-chloro-, 4,5-dichloro- and 2,4,5-trichloro- 1 -ethyl-3-methylimidazolium chloroaluminate; chlorination of a l-n-butyl-3-methylimidazolium (bmim+) chloroaluminate liquid gives 4-chloro- 1 -n-butyl-3-methylimidazolium chloroaluminate, 5-chloro- 1 -n-butyl-3-methylimidazolium chloroaluminate, 4,5-dichloro-l-n-butyl-3-methylimidazolium chloroaluminate and 2,4,5-trichloro- l-n-butyl-3-methylimidazolium chloroaluminate; and chlorination of l-ethyl-2,3-dimethylimidazolium (edmim+) chloroaluminate gives 4,5-dichloro- l-ethyl-2,3-dimethylimidazo um chloroaluminate by addition chlorination without any substitutive chlorination in the ethyl or n-butyl side chains occurring. Furthermore, we have found that the 2,4,5-trichloro- l-ethyl-3-methylimidazolium cation appears to be stable to further chlorination.
According to a further aspect of the present invention there is provided a chlorinated ionic liquid comprising a mixture of at least one suitable anion and at least one suitable cation containing covalently-bonded chlorine.
The chlorinated ionic liquid according to the present invention comprises at least one suitable anion as hereinafter defined and at least one suitable chlorinated cation which is preferably the cation of a chlorinated quaternary ammonium salt, more preferably a chlorinated quaternary ammonium salt ([R4N]X) wherein the hydrocarbyl groups R4 form a cyclic group with N and particularly more preferably a chlorinated 1,3-dialkylimidazolium salt.
Chlorinated ionic liquids according to the present invention tend to have higher viscosities and higher mp's than the corresponding ionic liquid. Where the at least one suitable cation in the chlorinated ionic liquid according to the further aspect of the present invention is an imidazolium salt the imidazolium cation may be mono-chlorinated, eg 4-chloro- l-alkyl-3-methylimidazolium chloride, 4-chloro- 1 -alkyl-2,3-dimethylimidazolium chloride, 5-chloro- 1 -alkyl-3-methylimidazolium chloride, 5-chloro-l-alkyl-2,3-dimethylimidazolium chloride; di-chlorinated, eg 4,5-dichloro-l-alkyl-3-methylimidazolium chloride, 4,5-dichloro-l-alkyl-2,3-dimethylimidazolium chloride; or tri-chlorinated, eg 2,4,5-trichloro- l-alkyl-3-methylimidazolium chloride, where alkyl is a C,.6 alkyl group, preferably ethyl, n-propyl, n-butyl, n-pentyl or n-hexyl, more preferably ethyl.
The chlorinated ionic liquid according to the present invention may be prepared by chlorination of a non-chlorinated ionic liquid as hereinbefore defined or alternatively the chlorinated cationic species can be prepared independently and converted into the chlorinated ionic liquid by appropriate reactions well known to those skilled in the art. For example, 5-chloro- 1,3-dimethylimidazo Hum chloride may be prepared by the process described by Blicke et al in J. Amer. Chem. Soc, 76, 3653 (1954) and 2,4,5-trichloro- 1,3-dimethylimidazolium chloride may be prepared by the process described by Janousek et al in Angew. Chem. Int. Edn., 18, 616, (1979). In the aforementioned alternative preparation of chlorinated ionic liquids, chlorinated cations have been synthesised as chloride salts by literature routes. They may be converted to ionic liquids by treatment with suitable anionic species, for example by treatment with appropriate amounts of aluminium chloride. According to a yet further aspect of the present invention there is provided a method for the preparation of a chlorinated ionic liquid by chlorination of a non-chlorinated ionic liquid or by conversion of a chlorinated cationic species into the chlorinated ionic liquid by treatment with suitable anionic species.
We have found surprisingly that chlorinated l-ethyl-3-ethylimidazolium-based ionic liquids, particularly the chloroaluminates, retain their liquid properties and, accordingly, are useful as ionic liquids in the processes according to the first and second aspects of the present invention.
Whereas the in situ formation of stable chlorinated ionic liquids during chlorination of a hydrocarbon, such as ethylene, is an embodiment of the present invention, it may be preferred to prepare the chlorinated ionic liquid separately prior to chlorination of the hydrocarbon.
The preferred cations of which the ionic liquids used in the first or second aspects of the present invention are comprised are those which surprisingly suppress substitutive chlorination, for example suppress the formation of β-Tri in the reaction of chlorine with ethylene. Such preferred cations include the chlorinated and unchlorinated 1,3-dialkylimidazolium species.
As examples of suitable anions may be mentioned inter alia fluorophosphates PF6 ", fluoroborates BF4 ", carboxylates, eg CH3CO2 ", fluorosulfonates, eg CF3SO3 ", fluoroalkylsulfonamides, eg (CF3SO2),N", nitrate NO3 ", trichloride Cl3 ", or preferably anions derived from a metal halide, which are known in the art as halometallates.
As examples of suitable metals of which the aforementioned halometallates may be comprised may be mentioned mter alia gallium, indium, iron, copper, zinc or preferably aluminium.
Where the suitable anion comprises a halometallate the halide is preferably chloride or bromide, more preferably chloride although we do not exclude the possibility that it may be fluoride or iodide.
It will be known to those skilled in the art that chlorometallates may exist as mixtures involving neutral metal halide, mononuclear, dinuclear and oligonuclear anions involved in acid-base equilibria. As examples of such complex chlorometallates may be mentioned chloroaluminates, A1C13/A1C14\ chloroferrates, FeCl3/FeCl4 ", chlorocuprates CuCl2 /CuCl3VCuCl4 2" and chlorozincates ZnCl2 /ZnCl37ZnCl4 2" and mixtures thereof.
Where the ionic liquid comprises a mixture of anions the mixture may comprise one or more anions which may be involved with such acid-base equilibria and/or one or more of, for example, fluorophosphate PF6 ", fluoroborate BF4 " , carboxylate, eg acetate CH3CO2 ", fluorosulphonate CF3SO3 " , fluoroalkylsulfonamides, eg (CF3SO2)2N\ nitrate NO3 ", and trichloride Cl3 ".
In the ionic liquid used in the processes according to the first or second aspects of the present invention wherein at least one of the anions is derived from a halometallate, the composition is chosen such that (i) a liquid phase is obtained under ambient conditions, preferably with as wide a liquid range as possible and (ii) the desired Lewis acidity/basicity of the liquid is obtained. It will be appreciated that the acidity/basicity is determined by the molar ratio of metal halide to halide ion, with the halide ion being provided in the form of the halide salt of the desired cation.
It will be appreciated that in ionic liquids derived from an aluminium halide, where the molar ratio of aluminium halide to organic salt is greater than 1, ie excess aluminium halide, the ionic liquid will be acidic, eg at 67 mole % aluminium halide the ionic liquid comprises A1C14 " and A12C17 ", and that where the molar ratio of aluminium halide to organic salt is less than 1, ie excess organic salt, the ionic liquid will be basic, eg at 40 mole % aluminium halide the ionic liquid comprises Cl" and A1C14 " .
For example, mixtures of l-ethyl-3-methylimidazolium chloride/aluminium chloride containing 40-67% aluminium chloride are liquid at 25°C thereby providing a chlorination catalyst/inhibitor combination and a reaction medium in which chlorination of ethylene and the ready separation of products can be effected.
Where the anion in the ionic liquid used in the processes according to the first or second aspects of the present invention is a halometallate the components of the ionic liquid can be mixed in any order as disclosed in US 5,104,840, the disclosure in which is incorporated herein by way of reference. The neat components may be mixed. Alternatively, the metal halide may be dissolved in an aliphatic solvent to form a solution which is mixed with the organic salt to obtain two liquid phases and the aliphatic solvent, typically the supernatant phase, is removed. Where the anion in the ionic liquid used in the processes according to the first or second aspects of the present invention is, for example, trifluoromethanesulfonate or tetrafluoroborate, the ionic liquid may be obtained by methods described in the literature. For example, l-ethyl-3-ethylimidazolium trifluoromethanesulfonate may be synthesised by the method described by Bonhote et al, Inorganic Chemistry, 1996, Vol.35, pi 176 by adding methyl trifluoromethanesulfonate in an argon atmosphere dropwise to 1-ethylimidazole in pure, dry 1,1,1-trichloroethane followed by reflux for 2 hours. After decantation, the molten salt is washed with 1,1,1-trichloroethane and dried under reduced pressure. In an alternative method, the preparation of 1 -ethyl-3-ethylimidazolium tetrafluoroborate by a double decomposition reaction of l-ethyl-3-ethylimidazolium chloride and lead (II) tetrafluoroborate, with the precipitated lead chloride being separated from the ionic liquid has been described in WO 96/18459 (Ellis).
In the ionic liquid used in the processes according to the present invention at least one of the anions is preferably derived from an aluminium or ferric halide group and the cation is preferably a quaternary ammonium salt.
As examples of halogenation reactions which may be carried out by the process according to the first aspect of the present invention may be mentioned inter alia conversion of ethylene into EDC, propylene into 1,2-dichloropropene, cyclohexene into 1 ,2-dichloro-cyclohexane and but-2-yne into 2,3-dichloro-2-butene.
The present invention is further illustrated by reference to the following Examples. Example 1
This Example illustrates the preparation of chlorinated ionic liquids according to the present invention.
Chlorine gas at 298K was bubbled through an acidic chloroaluminate ionic liquid prepared by mixing l-ethyl-3-methylimidazolium chloride and aluminium trichloride in molar ratio 1 :2. After 5 minutes, the nuclear magnetic resonance spectrum of the ionic liquid indicated the formation of 28% of a mixture of 4-chloro- 1 -ethy 1-3 -methy limidazolium cation and
5-chloro-l-ethyl-3-methylimidazolium cation. After bubbling chlorine the reaction mixture for a further 85 minutes at 298K, nuclear magnetic resonance indicated that 4,5-dichloro- l-ethyl-3-methylimidazolium cation was the sole cationic species present in the ionic liquid. After standing for a further 3 days with bubbling chlorine, nuclear magnetic resonance indicated the 2,4,5-trichloro-l-ethyl-3-methylimidazolium cation had been formed and after a further 20 days , nuclear magnetic resonance indicated that this trichloro- cation was the dominant cationic species. The medium remained liquid throughout the experiment. Examples 2-4
These Examples illustrate the preparation of further chlorinated ionic liquids according to the present invention.
Chloroaluminate ionic liquid (67 % acidic; 20 ml), prepared by mixing an imidazolium chloride and aluminium trichloride in molar ratio 1 :2 was placed in a schlenk tube with a magnetic stirrer and chlorine gas was bubbled through the ionic liquid at room temperature until analysis by Η and 13C NMR spectroscopy indicated that chlorination was complete.
The results are shown in Table 1.
Table 1
Figure imgf000012_0001
When Examples 2-4 were repeated using the corresponding 40% basic ionic liquid, the preparation of the dichloro- products in the repeats of Examples 2 and 3 was slower than in Examples 2 and 3 and the preparation of the dichloro-product in the repeat of Example 4 was much slower than in Example 4. Examples 5-9
These Examples illustrate the preparation of EDC by the process according to the present invention in an acidic chloroaluminate chlorinated ionic liquid.
Chlorine gas and ethylene were bubbled through 4,5-dichloro-l-ethyl-3-methylimidazolium tetrachloroaluminate prepared in Example 2 (67 % acidic; 3 ml) at room temperature (except Example 7 which was carried out at -18°C), in daylight (except Example 9 which was carried out in the dark), for 15 minutes. An exotherm and an increase in the volume of the reaction mixture were observed. The product was distilled out of the reaction mixture at room temperature and analysed by Η NMR and gas chromatography. The results are shown in Table 2.
Table 2
Figure imgf000013_0001
In Examples 5-7 the reaction product was found to comprise 1,1,2-trichloroethane, 1,1,2,2-tetrachloroethane, 1,1,1,2,2-pentachloroethane and hexachloroethane as well as EDC. Example 10
This Example illustrates the preparation of EDC by the process according to the present invention in a basic chloroaluminate.
Chlorine gas (30 ml/min) and ethylene (30 ml min) were bubbled through l-ethyl-3-methylimidazolium tetrachloroaluminate (40 % basic; 3 ml) at room temperature in daylight for 15 minutes. An exotherm (approx. 35°C) and an increase in the volume of the reaction mixture (appox. 1 ml) were observed.
The product was distilled out of the reaction mixture at room temperature and characterised as EDC by Η NMR spectroscopy (acetone d6; 300MHz;298°K): δ/p.p.m. 3.73(s, 4H, C2H4C12). Example 11
This Example illustrates the preparation of EDC by the process according to the present invention in an unchlorinated ionic liquid.
Example 10 was repeated except that l-n-butyl-3-methylimidazolium hexafluorophosphate, prepared by the process of Suarez et al, J. Chim. Phys., 95, 1626 (1998), was used instead of l-ethyl-3-methylimidazolium tetrachloroaluminate. An exotherm (approx. 35°C) and an increase in the volume of the reaction mixture (appox. 0.5 ml) were observed.
The product was distilled out of the reaction mixture at room temperature and characterised as EDC by Η NMR spectroscopy (acetone d6; 300MHz;298°K): δ/p.p.m. 3.73(s, 4H, C2H4C12).

Claims

Claims
1. A process for the halogenation of a hydrocarbon which is a C,.15 terminal or internal monoolefin, diolefin or polyolefin, a C 5 alkenyl-substituted aromatic, or an alkyne wherein the hydrocarbon is reacted with chlorine and/or bromine characterised in that the reaction is carried out in an ionic liquid.
2. A process as claimed in Claim 1 wherein the ionic liquid is a chlorinated ionic liquid.
3. A process as claimed in Claim 2 wherein the chlorinated ionic liquid is prepared in situ.
4. A process as claimed in Claim 1 wherein the halogen is chlorine.
5. A process as claimed in Claim 1 wherein the hydrocarbon is ethylene, propylene butylene, cyclhexene or but-2-yne.
6. A process as claimed in Claim 1 wherein the ionic liquid comprises a mixture of at least one anion derived from a metal halide and at least one cation of an organic salt derived from an amine, phosphine or sulphide.
7. A process as claimed in Claim 6 wherein the cation of an organic salt is the cation in a quaternary ammonium salt.
8. A process as claimed in Claim 7 wherein the hydrocarbyl groups in the quaternary ammonium salt form a azaheterocycle.
9. A process as claimed in Claim 8 wherein the quaternary ammonium salt is a 1 ,3 -dialkylimidazolium salt.
10. A process as claimed in Claim 9 wherein at least one of the alkyl groups in the 1,3-dialkylimidazolium salt is methyl.
11. A process as claimed in Claim 6 wherein the metal halide is an aluminium or ferric halide.
12. A process for the preparation of ethylene dichloride which comprises treating ethylene with elemental chlorine in an ionic liquid.
13. A chlorinated ionic liquid comprising a mixture of at least one suitable anion and at least one suitable cation containing covalently-bonded chlorine.
14. A chlorinated ionic liquid as claimed in Claim 13 wherein the chlorinated cation is the cation of an organic salt derived from an amine, phosphine or sulphide.
15. A chlorinated ionic liquid as claimed in Claim 14 wherein the chlorinated cation is the cation of a quaternary ammonium [R4N]X salt wherein the hydrocarbyl groups R, which may be the same or different, are C,.20 aliphatic (saturated or unsaturated) or aromatic.
16. A chlorinated ionic liquid as claimed in Claim 15 wherein the chlorinated cation is the cation of a quaternary ammonium [R4N]X salt wherein the hydrocarbyl groups R form a cyclic group with N.
17. A chlorinated ionic liquid as claimed in Claim 16 wherein the cyclic group formed by the hydrocarbyl groups R with N is a chlorinated 1,3-dialkylimidazolium cation.
18. A chlorinated ionic liquid as claimed in Claim 17 wherein at least one of the alkyl groups in the chlorinated 1,3-dialkylimidazolium cation is methyl.
19. A chlorinated ionic liquid as claimed in Claim 18 wherein the chlorinated 1,3-dialkylimidazolium cation is 4-chloro- l-alkyl-3-methylimidazolium, 4-chloro- l-alkyl-2,3-dimethylimidazolium, 5-chloro-l-alkyl-3-methylimidazolium, 5-chloro- l-alkyl-2,3-dimethylimidazolium, 4,5-dichloro- l-alkyl-3-methylimidazolium, 4,5-dichloro-l-alkyl-2,3-dimethylimidazolium or
2,4,5-trichloro- l-alkyl-3-methylimidazolium, where alkyl is a C,.6 alkyl group.
20. A chlorinated ionic liquid as claimed in Claim 19 wherein the 1 -alkyl group is ethyl, n-propyl, n-butyl, n-pentyl or n-hexyl.
21. A chlorinated ionic liquid as claimed in Claim 13 wherein the suitable anion is a fluorophosphate, fluoroborate, carboxylate, fluorosulfonate, fluoroalkylsulfonamide, nitrate, trichloride or preferably halometallate.
22. A chlorinated ionic liquid as claimed in Claim 21 wherein the metal of which the halometallate is comprised is gallium, indium, iron, copper, zinc or preferably aluminium.
23. A method for the preparation of a chlorinated ionic liquid as claimed in Claim 13 by chlorination of a non-chlorinated ionic liquid or conversion of a chlorinated cationic species into the chlorinated ionic liquid by treatment with suitable anionic species.
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WO2002092608A2 (en) * 2001-05-17 2002-11-21 Rhodia Chimie Use of a composition of an ionic nature as a substrate reagent, a composition constituting a fluorination reagent and a method using same
FR2824831A1 (en) * 2001-05-17 2002-11-22 Rhodia Chimie Sa Process for enabling nucleophilic substitution reactions, uses an ionic liquid or fused salt as a fluorinating medium
WO2003028883A1 (en) * 2001-10-02 2003-04-10 The Queen's University Of Belfast Catalyst comprising indium salt and organic ionic liquid and process for friedel-crafts reactions
FR2839716A1 (en) * 2002-05-15 2003-11-21 Rhodia Chimie Sa Process for enabling nucleophilic substitution reactions, uses an ionic liquid or fused salt as a fluorinating medium
FR2843113A1 (en) * 2002-07-31 2004-02-06 Rhodia Chimie Sa Process for electrophilic addition of a halogen to a carbon-carbon double bond in the presence of an ionic liquid to give an enantioselective halogenation with a significant enantiomeric excess
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WO2002030852A1 (en) * 2000-10-10 2002-04-18 The Queen's University Of Belfast Oxidative halogenation of aromatic compound
US7084317B2 (en) 2000-10-10 2006-08-01 The Queen's University Of Belfast Oxidative halogenation of aromatic compound
JP2004529956A (en) * 2001-05-17 2004-09-30 ロディア・シミ Use of ionic compositions as replacement reagents, compositions comprising fluorinated reagents and methods of using the same
WO2002092608A2 (en) * 2001-05-17 2002-11-21 Rhodia Chimie Use of a composition of an ionic nature as a substrate reagent, a composition constituting a fluorination reagent and a method using same
FR2824831A1 (en) * 2001-05-17 2002-11-22 Rhodia Chimie Sa Process for enabling nucleophilic substitution reactions, uses an ionic liquid or fused salt as a fluorinating medium
US7393980B2 (en) 2001-05-17 2008-07-01 Rhodia Chimie Use of a composition of an ionic nature as a substrate reagent, a composition constituting a fluorination reagent and a method using same
WO2002092608A3 (en) * 2001-05-17 2003-12-24 Rhodia Chimie Sa Use of a composition of an ionic nature as a substrate reagent, a composition constituting a fluorination reagent and a method using same
WO2003028883A1 (en) * 2001-10-02 2003-04-10 The Queen's University Of Belfast Catalyst comprising indium salt and organic ionic liquid and process for friedel-crafts reactions
US7928031B2 (en) 2001-10-02 2011-04-19 The Queen's University Of Belfast Catalyst comprising indium salt and organic ionic liquid and process for friedel-crafts reactions
FR2839716A1 (en) * 2002-05-15 2003-11-21 Rhodia Chimie Sa Process for enabling nucleophilic substitution reactions, uses an ionic liquid or fused salt as a fluorinating medium
FR2843113A1 (en) * 2002-07-31 2004-02-06 Rhodia Chimie Sa Process for electrophilic addition of a halogen to a carbon-carbon double bond in the presence of an ionic liquid to give an enantioselective halogenation with a significant enantiomeric excess
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WO2015142981A1 (en) * 2014-03-21 2015-09-24 E I Du Pont De Nemours And Company Processes for the production of z 1,1,1,4,4,4 hexafluoro 2-butene
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