WO2012113778A1

WO2012113778A1 - Process for the hydrohalogenation of an alkyne and for the manufacture of vinyl chloride by hydrochlorination of acetylene

Info

Publication number: WO2012113778A1
Application number: PCT/EP2012/052911
Authority: WO
Inventors: Michel Strebelle; Christian Franck
Original assignee: Solvay Sa
Priority date: 2011-02-24
Filing date: 2012-02-21
Publication date: 2012-08-30
Also published as: CN103391911A; EA025978B1; EA201391220A1; CN107417487A

Abstract

Process for the hydrohalogenation of an alkyne and for manufacturing vinyl chloride by hydrochlorination of acetylene in the presence of a catalytic system comprising at least one ionic liquid comprising at least one non-protonated cation, according to which said process is carried out in apparatus made from or covered with materials which are resistant to halogenated acids and more particularly HC1, in dissociated form.

Description

Process for the hydrohalogenation of an alkyne and for the manufacture of vinyl chloride by hydrochlorination of acetylene

The present invention relates to a process for the hydrohalogenation of an alkyne and for manufacturing vinyl chloride by hydrochlorination of acetylene.

The manufacture of vinyl chloride by reaction between acetylene and hydrogen chloride is conventionally carried out in the gas phase, in a fixed-bed reactor, in the presence of a heterogeneous solid catalyst based on mercury chloride on a support. Mainly for reasons of toxicity, there is currently an increasing interest in catalytic systems with decreased mercury content or which are free of mercury compounds.

Various catalysts intended to replace the current catalysts in gas-phase processes have been developed.

For example, unexamined Japanese Patent Application 52/136104 describes a process of hydrochlorinating acetylene in the gas phase in the presence of a fixed catalyst bed composed of noble metal halides deposited on active carbon. To date however, the lifetime of such alternative catalysts intended for gas-phase processes remains much shorter than that of catalysts based on mercury compounds.

Furthermore, in the literature there are some examples of hydrochlorinating acetylene in the presence of a liquid catalytic medium.

German Patent 709.000 describes a process for preparing vinyl halides by bringing acetylene into contact, at high temperatures, with a molten mass of hydrohalide salts of organic bases containing a standard catalyst. Aliphatic, aromatic or heterocyclic amines and mixtures thereof are envisaged as organic bases.

Inventor's certificate SU 237116 describes the use of an aqueous acid solution containing 46 wt % of cuprous chloride and from 14 to 16 wt % of a methylamine, dimethylamine or trimethylamine hydrochloride.

European Patent Application EP-A-0 340 416 discloses a process for preparing vinyl chloride by reaction of acetylene with hydrogen chloride in the presence of a palladium compound as catalyst in a solvent composed of an aliphatic or cycloaliphatic amide, at a temperature above room temperature. Although it allows high yields to be obtained, this process has, however, some significant drawbacks: it has emerged that, under the reaction conditions, the liquid catalyst system gradually degrades, forming blackish products of carbonaceous appearance. In addition, in the presence of hydrogen chloride, the amide is converted to a hydrochloride, the melting point of which is generally much higher than room temperature. N-Methylpyrrolidone hydrochloride, for example, is only liquid above 80°C. In practice, this may cause serious implementation problems, problems linked to agglomeration of the catalytic medium during reactor shutdowns or blocking of the lines at the coldest points of the installation. The entire reactor and also the lines in which the reaction medium flows must then be continuously kept at a temperature above the melting point of the hydrochloride.

These various problems seemed to have been solved thanks to the catalytic hydrochlorination systems described in European Patent Applications

EP 0 519 548-A1 and EP 0 525 843-A1 and which comprise at least one group VIII metal compound and either an amine hydrochloride, the melting point of which is less than or equal to 25°C, or a fatty amine hydrochloride comprising more that 8 carbon atoms, the melting point of which is above 25°C and an organic solvent chosen from aliphatic, cycloaliphatic and aromatic hydrocarbons and mixtures thereof. Nevertheless, the catalyst systems that are described therein, especially those of which the group VIII metal compound is

platinum (II) chloride or palladium (II) chloride, are not completely satisfactory when considering the performances that they enable to be achieved in terms of productivity of the vinyl chloride produced by hydrochlorination of acetylene and in terms of long term stability.

WO 2008/77868 discloses a catalytic hydrochlorination system comprising at least one amine hydrochloride and at least one group VIII metal compound selected from the group composed of mixtures of a platinum (IV) compound with Sn(II) chloride, mixtures of a platinum (II) compound with

triphenylphosphine oxide and mixtures of a palladium (II) compound with triphenylphosphine. These catalytic systems show an improved productivity compared to the systems as described in European patent applications

EP-A 0519548 and EP- A 0525843.

Finally, patent application CN 101716528 (citing Zhiyong Yu as inventor) discloses catalytic systems for production of vinyl chloride by the

hydrochlorination of acetylene comprising an imidazolium (which is a non- protonated cation)-based ionic liquid with chloride, bromide, hexafluorophosphate or tetrafluorophosphate ion as anion and one or more of gold, platinum, palladium, tin, mercury, copper or rhodium chlorides.

The last above-mentioned catalytic system seems to lead to high selectivity and high conversion rates at least when it is used in lab apparatus made of chemically inert material (like glass or Pyrex). In that regard, publication Green Chem., 2011, 13, 1495 having Zhiyong Yu as one of the authors, explicitly describes a glass reactor without mentioning any corrosion problem. In fact, glass was not chosen on purpose for corrosion problems but was merely the fall back material used for general purpose lab apparatus.

However, the Applicant noticed that surprisingly, the materials used in the industrial facilities handling the processes of the above mentioned patents using an amine hydrochloride, were rapidly and severely corroded if submitted to the above described imidazolium containing hydrochlorination medium. And from some testing, the Applicant noticed that this problem seems to be generalized to ionic liquids comprising at least one non-protonated cation and HC1.

The Applicant then found that surprisingly, when using materials which are resistant to dissociated HC1 (i.e. to HC1 dissociated in active protons and chloride anions), this problem almost disappears. This is quite surprising since there is no water in the reaction medium (while HC1 dissociation is known to be promoted by the presence of water) and since in the former hydrochlorination processes using an amine hydrochloride, the presence of HC1 didn't seem to induce corrosion problems. In fact, the same problem occurs with all halogenated acids, so not only with hydrogen chloride, but also with hydrogen iodide, with hydrogen fluoride and with hydrogen bromide. Such acids can be used for the hydrogenation of an alkyne i.e. a compound in which two carbons are linked by a triple bond. Among such alkynes can be cited acetylene, propyne also called methylacetylene, dimethylacetylene dicarboxylate, 1,4-butynediol as well as propargylic compounds.

The invention therefore relates to a process for the hydrohalogenation of an alkyne (preferably acetylene) in the presence of a catalytic system comprising at least one ionic liquid comprising at least one non-protonated cation, according to which said process is at least partly carried out in apparatus made from or covered with materials which are resistant to halogenated acids in dissociated form and which are chosen from metals, polymers, ceramics, refractory materials, (impregnated) graphite and enamel. A preferred embodiment of the invention relates to a process for manufacturing vinyl chloride by hydrochlorination of acetylene in the presence of a catalytic system comprising at least one ionic liquid comprising at least one non-protonated cation, according to which said process is at least partly carried out in apparatus made from or covered with materials which are resistant to HCl in dissociated form and which are chosen from metals, polymers, ceramics, refractory materials, (impregnated) graphite and enamel.

By the terms "at least partly carried out" is meant that at least that part of the apparatus where the reaction is carried out, and which is in contact with the reaction medium, is made of one of the above mentioned corrosion resistant materials.

By the terms "resistant to halogenated acids (HCl) in dissociated form" is meant that the concerned materials can be used for said part of the apparatus during a normal industrial life time (several years, typically at least 10 years) without needing to be replaced or repaired.

In the present description, the term "acetylene" has to be understood as acetylene or mixtures comprising acetylene which can, in addition to acetylene, comprise other components, e.g. ethylene or other unsaturated hydrocarbons which may be by-products of acetylene synthesis. The origin of such mixtures of different unsaturated compounds can be any known source of reaction mixtures as they may be obtained in the course of the known synthesis methods for acetylene. Mixtures comprising less than 50 % of acetylene can be used.

Preferably however, the term "acetylene" refers to mixtures comprising at least 90 % of acetylene and more preferably 100 % of acetylene.

Acetylene is mainly manufactured by the partial combustion of methane or appears as a side product in the ethylene stream from cracking of hydrocarbons.

Another method for the manufacture of acetylene is the hydrolysis of calcium carbide

CaC₂ + 2H₂0→ Ca(OH)₂ + C₂H₂

which requires extremely high temperatures of approximately 2000°C, necessitating the use of an electric furnace or the like.

Mixtures comprising acetylene and ethylene may be used directly as such, i.e. without the necessity to separate the components as the reactivity of acetylene vs. ethylene enables the hydrochlorination of acetylene to be carried out first with separation of the vinyl chloride obtained and the subsequent use of ethylene. This ethylene can be chlorinated to produce 1,2-dichoroethane for a combined process for the manufacture of vinyl chloride monomer. The pyrolysis of the 1,2-dichloroethane can produce the hydrogen chloride for the first reaction with acetylene. The hydrochlorination reaction according to the invention can advantageously be carried out at a temperature in the range of from room temperature to 220°C. At higher temperatures, the catalytic system has a tendency to degrade. The preferred reaction temperature, that is to say that offering the best compromise between productivity, yield and stability of the catalytic medium, is greater than or equal to about 40°C. The best results are obtained at temperatures greater than or equal to about 50°C with a more particular preference for temperatures greater than or equal to about 80°C and a most particular preference for temperatures greater than or equal to about 120°C. Preferably, the reaction temperature does not exceed about 200°C. A reaction temperature of about 40°C to about 200°C is most particularly preferred. In certain cases a reaction temperature not exceeding 170°C has proven

advantageous.

The hydrochlorination reaction according to the invention is

advantageously carried out at atmospheric pressure or at higher pressures compatible with the safety regulations for handling acetylene. Usually the pressure will not exceed 5 MPa, preferably it will not exceed 2.5 MPa acetylene partial pressure.

The hydrochlorination of acetylene according to the invention is advantageously carried out by bringing the gaseous reactants - acetylene and hydrogen chloride - into contact with the catalytic system, in any suitable reactor.

The hydrochlorination reaction according to the invention may be carried out conventionally in any equipment promoting gas-liquid exchange, such as a plate column, a flooded packed column or a flooded non-packed column.

Another embodiment of the process enabling good exchange of matter between the liquid and gas phases consists of the use of a countercurrent reactor, optionally of the sparged packed-bed type, the liquid catalytic system flowing over the packing, countercurrently to the gaseous flow of reactants.

In the process according to the invention the molar ratio of the hydrogen chloride to the acetylene introduced into the reactor is advantageously greater than or equal to about 0.5. Preferably, this ratio is greater than or equal to about 0.8. Advantageously, this molar ratio is less than or equal to about 3. Preferably, the molar ratio of the hydrogen chloride to the acetylene introduced into the reactor is less than or equal to about 1.5. Good results have been obtained when the hydrogen chloride and the acetylene are used in a molar ratio of about 0.5 to about 3.

The acetylene and the hydrogen chloride may be brought into contact in the reactor or, preferably, mixed prior to being introduced into the reactor.

For the purpose of increasing the amount of acetylene dissolved in the liquid phase, it is also possible to use a process in which only the acetylene is introduced into the reactor in gaseous form, where it reacts with the hydrogen chloride present in the liquid phase in hydrochloride form. The hydrogen chloride can be introduced in any form : dilute gaseous, pure or dissolved in a solvent to be extracted, such as for example an insoluble amine, advantageously then with an intermediate drying operation.

The catalytic system used according to the instant invention comprises at least one ionic liquid comprising at least one non-protonated cation and at least one anion.

Ionic liquids are in principle salts in the liquid state while ordinary liquids, such as e.g. water and gasoline are predominantly made of electronically neutral molecules. Ionic liquids are advantageously made of ions.

It may be generally said that any salt melting without decomposition will usually yield an ionic liquid. Many salts, however, melt at high temperatures, much higher than the temperatures used in catalytic processes. For the purposes of the instant invention the term ionic liquid shall refer to a system being liquid at temperature used in the process in which the catalytic system is used.

Preferred ionic liquids for the purposes of the instant invention are those which are liquid at temperatures of 150°C or less, more preferably at temperatures of 100°C or less even more preferably at temperatures of 80°C or less. Most preferred are ionic liquids which are in the liquid state at room temperature or even below. Furthermore, preferred ionic liquids are those which have a very low vapor pressure and a very low flammability and which show a good electrical conductivity.

The ionic liquid, which advantageously functions as reaction medium, has preferably a solvent capability for the products and intermediates formed in the reaction.

In the present description, the expression "at least one ionic liquid" is understood to mean one or more than one ionic liquid.

Preferably, the catalytic system consists essentially of one ionic liquid as defined above. In the remainder of the text, the expression "ionic liquid" used in the singular or plural should be understood as denoting one or more than one ionic liquid, except where denoted otherwise.

In the present description, the expression "at least one non-protonated cation" is understood to mean one or more than one non-protonated cation.

Preferably, the ionic liquid comprises one non-protonated cation.

In the remainder of the text, the expression "non-protonated cation" used in the singular or plural should be understood as denoting one or more than one non-protonated cation, except where denoted otherwise.

The term non-protonated cations as used herein for the purpose of the instant invention shall mean cations which do not carry free hydrogen atom(s) at the atom(s) to which the positive charge of the cation is allocated.

Advantageoulsy, the non-protonated cation is selected from

- quaternary ammonium cations which can be represented by the general formula [ R¹R²R³R]⁺,

phosphonium cations which can be represented by the general formula

[PR¹R²R³R]⁺, and

cations comprising five or six-membered heterocycles which have at least

- pyrrolidinium cations of the general formula (III)

wherein radicals R and R¹ to R⁹ may, independently from one another, with the proviso that the radical carried by the atom(s) to which the positive charge of the cation is allocated is not hydrogen, each be hydrogen, an optionally substituted saturated or insaturated Ci-Cis alkyl group (preferably an optionally substituted saturated or insaturated Ci-Ci₆ alkyl group and more preferably an optionally substituted saturated or insaturated C1-C14 alkyl group), an optionally substituted saturated or insaturated C₂-C18 alkyl group with the carbon chain interrupted by one oxygen atom or an optionally substituted C₆-Ci₂ aryl group.

Preferably, the non-protonated cation is selected from quaternary ammonium cations, phosphonium cations, imidazolium cations, pyridinium cations and pyrrolidinium cations.

More preferably, the non-protonated cation is selected from phosphonium cations, imidazolium cations, pyridinium cations and pyrrolidinium cations.

Most preferably, the non-protonated cation is selected from phosphonium cations and imidazolium cations.

Examples of quaternary ammonium cations are tributylmethylammonium, butyltrimethylammonium, octyltrimethylammonium, tetramethylammonium, tetraethylammonium, tetrabutylammonium, methyltrioctylammonium,

2-hydroxyethyltrimethylammonium and diethylmethyl(2- methoxyethyl)ammonium.

Examples of phosphonium cations are triisobutylmethylphosphonium, tributylmethylphosphonium, ethyltributylphosphonium, tetrabutylphosphonium, tetraoctylphosphonium, tributyltetradecylphosphonium,

trihexyltetradecylphosphonium and benzyltriphenylphosphonium.

Examples of imidazolium cations are 1,3-dimethylimidazolium, l-ethyl-3- methylimidazolium, l-butyl-3 -methylimidazolium, l-pentyl-3- methylimidazolium, l-hexyl-3 -methylimidazolium, l-decyl-3- methylimidazolium, l-dodecyl-3 -methylimidazolium, l-tetradecyl-3- methylimidazolium, l-hexadecyl-3 -methylimidazolium, l-(2-hydroxyethyl)-3- methylimidazolium, l-Allyl-3 -methylimidazolium, l-benzyl-3- methylimidazolium, l-phenylpropyl-3 -methylimidazolium, 1,3- diethylimidazolium, l-butyl-3 -ethylimidazolium, l-methyl-3- propylimidazolium, l-methyl-3-octylimidazolium, l-methyl-3- octadecylimidazolium, l,3-dibutyl-2-methylimidazolium, l,3-didecyl-2- methylimidazolium, l-(2-hydroxyethyl)-3 -methylimidazolium, l-ethyl-2,3- dimethylimidazolium, l-propyl-2,3-dimethylimidazolium, l-butyl-2,3- dimethylimidazolium, l-butyl-3,4-dimethylimidazolium, l-hexyl-2,3- dimethylimidazolium, l-hexadecyl-2,3-dimethylimidazolium,

1,2,3-trimethylimidazolium, 1,3,4-trimethylimidazolium, l-butyl-3- ethylimidazolium, 1,3-dibutylimidazolium, l-methyl-3-octylimidazolium, l-butyl-3,4,5-trimethylimidazolium and 1,3,4,5-tetramethylimidazolium.

Examples of pyridinium cations are 1-methylpyridinium,

1-ethylpyridinium, 1-propylpyridinium, 1-butylpyridinium, 1-hexylpyridinium, 1 -octyl pyridinium, 1 ,2-dimethylpyridinium, 2-ethyl- 1 -methylpyridinium, 1 -butyl-2-methylpyridinium, 1 -butyl-3 -methylpyridinium, 1 -butyl-4- methylpyridinium, l-hexyl-3 -methylpyridinium, l-hexyl-4-methylpyridinium, 1 -butyl-2-ethylpyridinium, 1 -butyl-3 -ethylpyridinium, 4-methyl- 1 - octyl pyridinium, 1 -butyl-2-ethyl-6-methylpyridinium, 2-ethyl- 1,6- dimethylpyridinium, 1 -butyl-3, 4-dimethylpyridinium and 1 -butyl-3, 5- dimethylpyridinium.

Examples of pyrrolidinium cations are 1, 1 -dimethyl pyrrolidinium, 1-ethyl-

1-methylpyrrolidinium, l-ethyl-3-methylpyrrolidinium, 1 -butyl- 1- methylpyrrolidinium, 1-hexyl-l -methyl pyrrolidinium, 1 -octyl- 1- methylpyrrolidinium, 1 -butyl- 1-ethylpyrrolidinium and 1 -methyl- 1- propylpyrrolidinium.

In the present description, the expression "at least one anion" is understood to mean one or more than one anion.

Preferably, the ionic liquid comprises one anion.

In the remainder of the text, the expression "anion" used in the singular or plural should be understood as denoting one or more than one anion, except where denoted otherwise.

As anions, it is in principle possible to use all anions. The anion [Y] is preferably selected from:

the group consisting of halides and halogen-containing anions and so called pseudo-halides of the formulae:

C1-, Br-, BF4-, PF6-, A12C14-, A12C17-, FeC14-, BC14-, SbF6-, AsF6-, ZnC13-,

SnC13, CF3S03-, (CF3S03)2N-, CF3C02-, CC13C02-, CN-, SCN- and OCN-, the group consisting of sulfates, sulfites and sulfonates of the general formulae:

S042-, HS04-, S032-, HS03-, RaOS03-, RaS03-,

the group consisting of phosphates of the general formulae:

P043 -, HP042-, H2P04-, RaP042-, HRaP04-, RaRbPC-4-,

the group consisting of phosphonates and phosphinates of the general formulae: RaHP03-, RaRbP02-, RaRbP03-,

the group consisting of phosphites of the general formulae:

P033-, HP032-, H2P03-, RaP032-, RaHP03-, RaRbP03

the group consisting of phosphonites and phosphinites of the general formulae: RaRbP02-, RaHP02-, RaRbPO-, RaHPO-,

the group consisting of carboxylic acids of the general formula: RaCOO-, the group consisting of borates of the general formulae:

B033-, HB032-, H2B03-, RaRbB03-, RaHB03-, RaB032-,

the group consisting of boronates of the general formulae:

RaB022-, RaRbBO-,

the group consisting of carbonates and carbonic esters of the general formulae: HC03-, C032-, RaC03-,

the group consisting of silicates and silicic esters of the general formulae:

Si044-, HSi043-, H2Si042-, H3Si04-, RaSi043-, RaRbSi042-, RaRbRcSi04-, HRaSi042-, H2RaSi04-, HRaRbSiCH-,

the group consisting of alkylsilane and arylsilane salts of the general formulae: RaSi033-, RaRbSi032-, RaRbRcSiO-, RaRbRcSi03-, RaRbRcSi02-,

RaRbSi032-,

the group consisting of carboximides, bis(sulfonyl)imides and sulfonylimides of the general formulae:

the group consisting of alkoxides and aryloxides of the general formula: RaO-, and the group consisting of complex metal ions such as Fe(CN)63-, Fe(CN)64-, Mn04-, Fe(CO)4 ,

and where the radicals Ra, Rb, Rc are each, independently of one another, Cl- C18-alkyl, C2-C18-alkyl the carbon chain of which may be interrupted by one or more phosphorus, oxygen and/or sulfur atoms and/or one or more substituted imino groups, C6-C12-aryl, C5-C12-cycloalkyl or a five- or six-membered, phosphorus-, oxygen-, nitrogen- and/or sulfur-containing heterocycle or two of them together form an unsaturated, saturated or aromatic ring which may be interrupted by one or more phosphorus, oxygen and/or sulfur atoms and/or one or more substituted imino groups, where the radicals mentioned may each be substituted by functional groups, aryl, alkyl, aryloxy, alkyloxy, halogen, heteroatoms and/or heterocycles.

Preference is given to Ra, Rb and Rc, each being, independently of one another, hydrogen, methyl, ethyl, n-butyl, 2-hydroxyethyl, 2-cyanoethyl, 2- (methoxycarbonyl)ethyl, 2-(ethoxycarbonyl)ethyl, 2-(n-butoxycarbonyl)ethyl and chlorine.

The anion(s) are preferably chosen among the following ones: chloride, bromide, iodide, triflate (trifluoromethanesulfonate), tosylate,

tetrafluoroethyl sulfonate, bis-trifluoromethylsulfonylimide, tetrachloroferrate, tetrafluorob orate, tetrafluorophosphate and hexafluorophosphate.

Methods for the manufacture of suitable ionic liquids are known to the skilled man and thus a detailed description is not necessary here.

The catalytic system in accordance with the instant invention may be used in the liquid phase or be deposited on a solid support such as a silica, alumina, silica alumina, cordierite, mullite or activated carbon (to name only a few suitable support materials), up to the limit of the pore volume and the available surface of the support. The support can have any shape known for such support materials, including but not limited to honeycombs and extrudates or the like.

When it is used in the liquid phase, the catalytic system may be diluted by an organic solvent. The choice of the nature of the organic solvent then included in the catalytic system according to the invention especially depends on the requirement that it be inert with respect to the reactants under the reaction conditions, that it be miscible or not with the ionic liquid and on the desire that it forms with this ionic liquid a medium, the viscosity of which is lower than that of the ionic liquid alone.

Preferably, however, the ionic liquid acts as a solvent so that no further solvent is used.

In a first preferred embodiment of the invention, the catalytic system consists essentially of at least one ionic liquid comprising at least one non- protonated cation and at least one anion selected from chloride and

methanesulfonate.

The expression "consisting essentially of is understood to mean, in the present description, that besides the at least one ionic liquid as defined, the catalytic system according to the invention may comprise additional

component(s), preferably in small amount, that do not have an effect on the catalytic properties of the catalytic system; in other words that do not have a catalytic effect on the reaction during which the catalytic system is used. Among such additional component(s) may be cited ionic liquid(s) other than the ionic liquid(s) defined above, added for example to decrease the viscosity of the catalytic system.

The catalytic system according to the first embodiment of the invention consists essentially of at least one ionic liquid comprising at least one non- protonated cation and at least one anion selected from chloride and

methanesulfonate with the preferences listed above for the non-protonated cation.

Preferably, the ionic liquid is selected from quaternary ammonium chlorides, quaternary ammonium methanesulfonates, phosphonium chlorides, phosphonium methanesulfonates, imidazolium chlorides, imidazolium methanesulfonates, pyridinium chlorides, pyridinium methanesulfonates, pyrrolidinium chlorides and pyrrolidinium methanesulfonates.

More preferably, the ionic liquid is selected from phosphonium chlorides, phosphonium methanesulfonates, imidazolium chlorides, imidazolium methanesulfonates, pyridinium chlorides, pyridinium methanesulfonates, pyrrolidinium chlorides and pyrrolidinium methanesulfonates.

Most preferably, the ionic liquid is selected from phosphonium chlorides, phosphonium methanesulfonates, imidazolium chlorides and imidazolium methanesulfonates.

Particularly preferred ionic liquids are selected from l-butyl-3- methylimidazolium chloride, trihexyltetradecylphosphonium chloride, l-ethyl-3- methylimidazolium methanesulfonate, l-methyl-3-octylimidazolium chloride, 1- Ethyl-3-methylimidazolium chloride and l-benzyl-3 -methylimidazolium chloride.

Particularly preferred ionic liquids are those commercially available from Iolitec GmbH or from BASF SE.

In a second preferred embodiment of process according to the instant invention, the catalytic system comprises:

a) at least one N-alkylated imidazole and/or the corresponding imidazolium; and b) optionally at least one compound of at least one metal.

The expression "comprises" is understood to mean, in the present description, that besides the at least one N-alkylated imidazole and/or the corresponding imidazolium and the optionally at least one compound of at least one metal, the catalytic system according to the invention may comprise additional component(s) having an effect on the catalytic properties of the catalytic system or not. Among such additional component(s) may be cited ionic liquid(s) added for example to have an effect on the catalytic properties of the catalytic system and/or allow a decrease of the viscosity of the catalytic system.

Preferably, the catalytic system according to the invention consists essentially of

The expression "consists essentially of has the same meaning as defined above for the first embodiment of the invention.

The expression "at least one N-alkylated imidazole and/or the

corresponding imidazolium " is understood to mean one or more than one N- alkylated imidazole and/or the corresponding imidazolium.

Preferably, the catalytic system of the second embodiment of the invention comprises one N-alkylated imidazole and/or the corresponding imidazolium.

In the remainder of the text, the expression " N-alkylated imidazole and/or the corresponding imidazolium" used in the singular or plural should be understood as denoting one or more than one N-alkylated imidazole and/or the corresponding imidazolium, except where denoted otherwise.

N-alkylated imidazoles according to the second embodiment of the invention is advantageously defined by formula (I) here below

wherein radicals R¹, R², R³ and R⁴ may, independently from one another, each be hydrogen or an optionally substituted saturated or insaturated Ci-Cis (preferably C1-C14, more preferably C1-C12, most preferably C1-C10 and particularly most preferably Ci-C₈) alkyl group.

Examples of N-alkylated imidazoles are 1-methylimidazole, 1- ethylimidazole, 1-propylimidazole, 1-butylimidazole, 1-pentylimidazole, 1- hexylimidazole, 1-heptylimidazole, 1-octylimidazole, 1-nonylimidazole, 1- decylimidazole, l-methyl-2-octylimidazole, l-ethyl-2-methylimidazole, 1-butyl- 2-methylimidazole, l-hexyl-2-methylimidazole and l-decyl-2-methylimidazole. Preferably, the N-alkylated imidazole is selected from 1-methylimidazole,

1- ethylimidazole, 1-butylimidazole, 1-hexylimidazole, 1-octylimidazole, 1- decylimidazole, l-methyl-2-octylimidazole, l-ethyl-2-methylimidazole, 1-butyl-

2- methylimidazole, l-hexyl-2-methylimidazole and l-decyl-2-methylimidazole.

More preferably, the N-alkylated imidazole is selected from 1- methylimidazole, 1-ethylimidazole and 1-butylimidazole. Those most preferred N-alkylated imidazoles are e.g. commercially available from Aldrich^®.

Methods for the manufacture of suitable alkylated imidazoles are known to the skilled man and thus a detailed description is not necessary here.

The catalytic system according to the second embodiment of the invention comprises as component b) optionally at least one compound of at least one metal.

The expression "at least one compound of at least one metal" as used herein includes single metal compounds of one metal as well as mixtures of different compounds of the same metal or mixtures of compounds of different metals or compounds comprising two metals as defined hereinbefore, i.e. the catalytic systems in accordance with the second embodiment of the invention may comprise more than one metal respectively metal compounds as defined above.

Preferably, the catalytic system comprises one compound of at least one metal and more preferably one compound of one metal.

The expressions "compound" and "metal" used in the singular or plural should be understood as denoting respectively one or more than one compound and one or more than one metal, except where denoted otherwise.

The expression "comprises optionally at least one compound" is understood to mean that such compound is present or not in the catalytic system.

According to a first sub-embodiment, the catalytic system according to the second embodiment of the invention comprises advantageously component a) i.e. at least one N-alkylated imidazole and/or the corresponding imidazolium. In other words, the catalytic system does advantageously not comprise component b) i.e. at least one compound of at least one metal.

According to a second sub-embodiment, the catalytic system comprises advantageously

a) at least one N-alkylated imidazole and/or the corresponding imidazolium; and b) at least one compound of at least one metal. In the second embodiment of the invention, the metal can be any metal. The metal is advantageously chosen from Pd, Pt, Au, Hg, Ru, Os, Ru, Rh and Ir. Preferably, the metal is chosen from Pd, Pt, Au, Hg, Ru and Os.

The catalytic system according to the second embodiment of the invention comprises therefore preferably

a) at least one N-alkylated imidazole and/or the corresponding imidazolium; and b) at least one compound of at least one metal chosen from Pd, Pt, Au, Hg, Ru and Os.

While good results have been obtained when the metal is chosen among the ones cited above, very good results have been obtained when the metal is chosen from Pd, Ru, Au and Os, particularly very good results have been obtained when the metal is chosen from Pd, Ru and Au and more particularly very good results have been obtained when the metal is chosen from Pd and Ru. The most interesting results have been obtained when metal is Pd.

Preferred Pt(IV) or Pt(II) or Pd(II) compounds are those which can be converted into chlorides of the mentioned metals during the preparation of the catalytic system in accordance with the instant invention. Thus, chlorides, nitrates, acetates, carbonates or oxides of platinum (IV), platinum (II) or palladium (II) may be used. Chlorides and acetates of these metals are nevertheless preferred.

Among the chloride-based compounds of platinum (IV), mention may be made of platinum (IV) chloride and hexachloroplatinic acid or its salts, for example Na₂PtCl₆, K₂PtCl₆ or Li₂PtCl₆.

Among the chloride-based compounds of platinum (II), mention may be made of platinum (II) chloride and the platinochlorides of alkali metals or of alkaline-earth metals, such as for example Na₂(PtCl₄), K₂(PtCl₄), Li₂(PtCl₄) and ( H₄)₂(PtCl₄).

Among the chloride-based compounds of palladium (II), mention may be made of palladium (II) chloride and the palladochlorides of alkali metals or of alkaline-earth metals, such as for example Na₂(PdCl₄), K₂(PdCl₄), Li₂(PdCl₄) and ( H₄)₂(PdCl₄).

Particularly preferably, PtCl₄, PtCl₂, PdCl₂ and palladium (II) acetate are chosen as compounds of platinum (IV), platinum (II) and palladium (II) respectively. PtCl₂, PdCl₂ and palladium (II) acetate are most preferred. Among compounds of Au, Au³⁺ compounds are preferred and, similarly as in the case of Pd and Pt, those compounds which can be converted into chlorides are preferred. AuCl₃ is most preferred.

Suitable compounds of Ru, and Os are those of valency 3 and again those compounds which can be converted into chlorides or the chlorides themselves are particularly preferred. RuCl₃ and OsCl₃ are respectively most preferred.

Amongst the suitable compounds of Hg, HgCl₂ may be mentioned.

The content of metal compound in the catalytic system according to the second sub-embodiment, expressed in millimoles per litre of N-alkylated imidazole and/or the corresponding imidazolium is advantageously greater than or equal to about 1 mmol/1 and less than or equal to about 1000 mmol/1. The content of metal compounds in the catalytic system according to the second embodiment is advantageously greater than or equal to about 1 mmol/1, preferably greater than or equal to about 5 mmol/1 and particularly preferably greater than or equal to about 10 mmol/1. The content of metal compound in the catalytic system is advantageously less than or equal to about 1000 mmol/1, preferably less than or equal to about 800 mmol/1, particularly preferably less than or equal to about 600 mmol/1, more particularly preferably less than or equal to about 500 mmol/1 and most particularly preferably less than or equal to about 400 mmol/1. Although it is not mandatory, it is however preferable that all the metal compounds included in the catalytic system be in dissolved form.

Generally, the catalytic system in accordance with the second sub- embodiment is prepared by dissolving or dispersing the desired amount of metal compound in the N-alkylated imidazole and/or the corresponding imidazolium, and then saturating this solution with hydrogen chloride. However, it is also possible to first saturate the N-alkylated imidazole and/or the corresponding imidazolium with hydrogen chloride then to next introduce the metal compound into the N-alkylated imidazole and/or the corresponding imidazolium. Usually, the amount of metal compound used is such that, in the catalytic system, the entire metal compound is in dissolved form. However, it is also possible to use a metal compound in an amount or of a nature such that at least one fraction of this compound is present in the catalytic system in the form of a dispersed solid, without prejudicing the invention.

In a third preferred embodiment of the invention, the catalytic system comprises a mixture of: a) at least one compound of at least one metal one of which being chosen from palladium, platinum and osmium; and

b) at least one ionic liquid comprising at least one non-protonated cation and at least one anion ;

the mixture being chosen from the group of the mixtures comprising:

when the metal is palladium,

palladium (II) acetate and l-butyl-3 -methylimidazolium chloride or 1 -ethyl - 3-methylimidazolium chloride,

palladium (II) chloride, copper chloride and l-butyl-3 -methylimidazolium chloride,

palladium (II) chloride, cuprous chloride and l-butyl-3 -methylimidazolium chloride,

palladium (II) chloride and l-ethyl-3 -methylimidazolium chloride, 1- methyl-3-octylimidazolium chloride, l-benzyl-3 -methylimidazolium chloride, trihexyltetradecylphosphonium chloride or l-butyl-4- methylpyridinium bis(trifluoromethylsulfonyl)imide,

palladium (II) chloride, palladium (II) acetate and l-butyl-4- methylpyridinium bis(trifluoromethylsulfonyl)imide;

when the metal is platinum,

platinum (II) chloride and l-butyl-3 -methylimidazolium chloride, l-butyl-3 - methylimidazolium tetrachloroferrate, l-ethyl-3 -methylimidazolium chloride, l-ethyl-3 -methylimidazolium methanesulfonate, l-ethyl-3 - methylimidazolium tetrafluorethyl sulfonate, l-methyl-3-octylimidazolium chloride, l-methyl-3-octylimidazolium triflate or

trihexyltetradecylphosphonium chloride,

platinum (IV) chloride and l-ethyl-3 -methylimidazolium triflate or trihexyltetradecylphosphonium bis(trifluoromethylsulfonyl)imide, potassium hexachloroplatinate (IV) and l-ethyl-3 -methylimidazolium triflate; and

when the metal is osmium, osmium (III) chloride and l-butyl-3-methylimidazolium chloride, 1-ethyl- 3-methylimidazolium tetrafluorethyl sulfonate, l-methyl-3- octylimidazolium chloride or trihexyltetradecylphosphonium chloride.

The expression "comprises" is as defined above.

Preferably, the catalytic system according to the third embodiment of the invention consists essentially of the mixture of the at least one compound of at least one metal and the at least one ionic liquid as defined above.

The expressions "consists essentially of and "at least one compound of at least one metal" are also as defined above, for the first and/or second

embodiment.

The catalytic system according to the third embodiment of the instant invention comprises as component a) at least one compound of at least one metal one of which being chosen from palladium, platinum and osmium.

In the description of the third embodiment of the invention, the expression "at least one compound of at least one metal" includes single metal compounds of one metal as well as mixtures of different compounds of the same metal or mixtures of compounds of different metals or compounds comprising two metals as defined hereinbefore, i.e. the catalytic systems may comprise more than one metal respectively metal compounds as defined above.

In the description of the third embodiment of the invention, the expression

"one metal one of which being chosen from palladium, platinum and osmium" is understood to mean that one of the metal is palladium, platinum or osmium.

According to a first sub-embodiment of the third embodiment of the invention, the catalytic system comprises a mixture of a) and b) being chosen from the group of the mixtures comprising

palladium (II) acetate and l-butyl-3-methylimidazolium chloride or 1 -ethyl - 3-methylimidazolium chloride,

palladium (II) chloride, copper chloride and l-butyl-3-methylimidazolium chloride,

palladium (II) chloride, cuprous chloride and l-butyl-3-methylimidazolium chloride,

palladium (II) chloride and l-ethyl-3-methylimidazolium chloride, 1- methyl-3-octylimidazolium chloride, l-benzyl-3-methylimidazolium chloride, trihexyltetradecylphosphonium chloride or l-butyl-4-methylpyridinium bis(trifluoromethylsulfonyl)imide.

According to a second sub-embodiment of the third embodiment of the invention, the catalytic system comprises a mixture of a) and b) being chosen from the group of the mixtures comprising

platinum (II) chloride and l-butyl-3-methylimidazolium chloride, 1-butyl- 3-methylimidazolium tetrachloroferrate, l-ethyl-3-methylimidazolium chloride, l-ethyl-3-methylimidazolium methanesulfonate, l-ethyl-3-methylimidazolium tetrafluorethyl sulfonate, l-methyl-3-octylimidazolium chloride, l-methyl-3- octylimidazolium triflate or trihexyltetradecylphosphonium chloride,

platinum (IV) chloride and l-ethyl-3-methylimidazolium triflate or trihexyltetradecylphosphonium bis(trifluoromethylsulfonyl)imide,

potassium hexachloroplatinate (IV) and l-ethyl-3-methylimidazolium triflate.

According to a third sub-embodiment of the third embodiment of the invention, the catalytic system comprises a mixture of a) and b) being chosen from the group of the mixtures comprising

osmium (III) chloride and l-butyl-3-methylimidazolium chloride, l-ethyl-3- methylimidazolium tetrafluorethyl sulfonate, l-methyl-3 -octylimidazolium chloride or trihexyltetradecylphosphonium chloride.

While good results have been obtained with the catalytic system according to the three sub-embodiments of the third embodiment of the invention, very good results have been obtained with the catalytic system according to the first and the second sub-embodiments and particularly very good results have been obtained with the catalytic system according to the first sub-embodiment.

The content of the compound of at least one metal one of which being chosen from palladium, platinum or osmium in the catalytic system according to the third embodiment of the invention, expressed in millimoles per litre of ionic liquid is advantageously greater than or equal to 1 mmol/1 and less than or equal to 1000 mmol/1. The content of the compound as defined above is

advantageously greater than or equal to 1 mmol/1, preferably greater than or equal to 5 mmol/1 and particularly preferably greater than or equal to 10 mmol/1. The content of the compound as defined above is advantageously less than or equal to 1000 mmol/1 and preferably less than or equal to 900 mmol/1.

The content of the compound of palladium, platinum or osmium in the catalytic system according to the third embodiment of the invention, expressed in millimoles per litre of ionic liquid is advantageously greater than or equal to 1 mmol/1 and less than or equal to 1000 mmol/1. The content of the compound as defined above is advantageously greater than or equal to 1 mmol/1, preferably greater than or equal to 5 mmol/1 and particularly preferably greater than or equal to 10 mmol/1. The content of the compound as defined above is advantageously less than or equal to 1000 mmol/1, preferably less than or equal to 500 mmol/1, particularly preferably less than or equal to 200 mmol/1, more particularly preferably less than or equal to 100 mmol/1 and most particularly preferably less than or equal to 50 mmol/1.

Although it is not mandatory, it is however preferable that all the metal compounds included in the catalytic system be in dissolved form.

Generally, the catalytic system in accordance with the third embodiment of the invention is prepared by dissolving or dispersing the desired amount of metal compound in the ionic liquid, and then saturating this solution with hydrogen chloride. However, it is also possible to first saturate the ionic liquid with hydrogen chloride then to next introduce the metal compound into the ionic liquid. Usually, the amount of metal compound used is such that, in the catalytic system, the entire metal compound is in dissolved form. However, it is also possible to use a metal compound in an amount or of a nature such that at least one fraction of this compound is present in the catalytic system in the form of a dispersed solid, without prejudicing the invention.

According to a fourth preferred embodiment of the invention, the catalytic system is as the one claimed and described in patent application CN 101716528 (the content of which is incorporated by reference in the present application) i.e. a catalytic system comprising an imidazolium-based ionic liquid with chloride, bromide, hexafluorophosphate or tetrafluorophosphate ion as anion and one or more of gold, platinum, palladium, tin, mercury, copper or rhodium chlorides.

As explained above, the process according to the invention is at least partly carried out in apparatus made from or covered with materials which are resistant to HCl in dissociated form, namely: from metals, polymers, ceramics, refractory materials, (impregnated) graphite and enamel.

Without willing to be bound to a theory, the Applicant believes that although the process of the invention if generally carried out in the absence of water, the reaction medium is however so highly polar (ionic) that it boosts the dissociation of HCl in active protons and chloride anions leading to a largely accelerated corrosion of materials like stainless steels. Hence, as appropriate materials that can be used in the frame of the invention, mention may be made of both metallic and non-metallic materials.

These materials may be used either within the mass, or in the form of a coating, but which should be resistant to dissociated HC1.

Among the metallic materials, mention may be made of tantalum and tantalum alloys, zirconium and zirconium alloys, titanium and titanium alloys, platinum and the metals of the "platinum" group, silver and silver-gold- palladium alloys with a minimum of 30 % gold, gold and gold-silver alloys and gold-platinum alloys, molybdenum and molybdenum alloys, nickel-molybdenum alloys, nickel-chromium-molybdenum alloys, nickel-copper alloys, copper alloys (silicon bronze), copper-tantalum and copper-niobium alloys, tin-antimony alloys containing 5 % antimony, tin-nickel alloys, niobium and niobium- tantalum alloys.

Among the metals of the platinum group mention may be made of rhodium iridium, ruthenium, palladium and osmium.

Among the metallic materials, gold and tantalum are preferred. Tantalum, platinum and niobium gave good results even up to 150°C, temperature at which zirconium, silver and Ti-Pd alloys were severely corroded. Especially tantalum and tantalum based alloys (comprising more than 50% tantalum) are preferred metals in the frame of the invention

Specific HC1 resistant alloys may also be used, like for instance: Titanium grade 7, Hastelloy® B family, Alloy 400, stainless steel grade 904L and super austenitic stainless steels, or Hastelloy® Cfamily.

Among the non-metallic materials mention may be made of high-density polyethylene, fluoroelastomer-based elastomers, thermoplastics based on polypropylene, on fluoropolymers (like: Polytetrafluoroethylene : PTFE;

Fluorinated ethylene-propylene : FEP; Perfluoroalkoxy : PFA MFA;

Polychlorotrifluoroethylene : PCTFE; Polyvinylidene Fluoride : PVDF;

Polyvinyl Fluoride : PVF; Polyethylene Tetrafluoroethylene : ETFE;

Polyethylene Chlorotrifluoroethylene : ECTFE), ABS (acrylonitrile-butadiene- styrene) copolymers, acrylonitrile (40 %)-vinyl chloride (60 %) copolymer, polysulphones, polyphenylene (PPH) polymers like polyphenylene sulphides and polyphenyl sulphones, glass-resin laminates based on polyester resins, on phenolic resins, on furan resins, on epoxy resins and on vinyl ester resins, ceramics based on alumina and corundum, metalloceramic materials based on hafnium carbide and titanium nitride, refractory materials based on silicon carbide, on silica, on high-silica-content aluminium silicates, on zirconium silicate, on zirconium oxide and on sillimanite (AI₂O₃-S1O₂), coatings based on epoxy resin, on Sakaphen, on Brauthite on the basis of phenol-formaldehyde resin and of Isolemail ®, acid-resistant cements based on silicates, on phenol- formaldehyde resin and on sulphide mixed with quartz sand, self-curing acid- resistant cements based on phenol-formaldehyde resins admixed with graphite, furfuryl alcohol resins admixed with graphite, epoxy resins admixed with carbon and polyester resins admixed with quartz. In the case of the cements the substrate should be protected by an additional plastic sheet. Graphite,

Impregnated graphite (impregnated with polytetrafluoroethylene or with a phenolic resin), carbon, glass, quartz, enamel, porcelain, earthenware, stoneware and acid-resistant brick may also be suitable as non-metallic materials. Silicon carbide, alumina and (impregnated) graphite gave good results.

Among the polymers/resins that can be used, the following specific ones may also be mentioned: CPVC (of chlorinated PVC), Derakane ® 470, Daron ® XP 45, DCPD (dicyclopentadiene), ebonite and EPDM.

Enamel is advantageously used as a material for coating steel.

Among the polymers, those highly suitable include polyolefins such as high-density polyethylene (HDPE) ultra high molecular weight PE (UHMWPE) and polypropylene (PP) and in particular, thermoplastics based on

fluoropolymers, sulphur-containing polymers such as polysulphones or polysulphides, especially aromatic polymers of this kind, and graphite and impregnated graphite.

Among the thermoplastics based on fluoropolymers, those highly suitable include polyvinylidene fluoride, polytetrafluoroethylene,

perfluoroalkoxyalkanes, ethyl ene-tetrafluoroethylene copolymers,

tetrafluoroethylene-perfluoromethyl vinyl ether copolymers and

tetrafluoroethylene-hexafluoropropylene copolymers.

The polymers may be employed in the solid state or reinforced with a jacket (steel, hooped reinforcement like GRP).

Among the polymers/resins that can be used, PEEK (poly-ether-ether- ketone) and fluorinated polymers are preferred at least for high temperature (typically above 100°C) applications. As fluorinated polymers, PTFE, FEP, PFA-MFA (sold under the brand HYFLON®)), ETFE and ECTFE (like the one sold under the brand name HALER®) gave good results. For lower temperature applications, the following specific polymers gave good results: PP (or polypropylene) homopolymer and CPVC (of chlorinated PVC).

Among the coatings formed by means of resins, those based on epoxy resins or on phenolic resins are especially suitable. Plastic coatings may be applied for instance on steel or on GRP (glass reinforce polyester).

Depending on the working conditions and kind of apparatus, preferred materials for the coating or manufacture of apparatus for handling the process of the invention are graphite, graphite impregnated with polytetrafluoroethylene or with a phenolic resin, enamel, tantalum, gold, fluoropolymers, polyolefins and metal alloys.

For certain particular elements, for example heat exchangers and pumps, graphite, whether impregnated or not, is especially suitable. For the heat exchangers which allow heating or evaporation of the fluids in the process, graphite impregnated with polytetrafluoroethylene is especially suitable.

Enamel, tantalum, gold and perfluorinated polymers are highly suitable for the coating or manufacture of apparatus operating at high temperature.

Polyolefins, fluoropolymers and metal alloys are highly suitable for the coating or manufacture of apparatus operating at low temperature.

Especially enamelled steel (sometimes called "glass lined steel") seems to work well in the frame of the invention. It is indeed a cheaper solution than steel with a perfluorinated polymer liner and enamel shows a much better adhesion to steel than perfluorinated polymers.

Hence, preferably, the process of the invention is at least partly carried out in apparatus made from enamelled steel i.e. at least one piece of the apparatus used for the process of the invention is made of enamelled steel.

In that regard, preferred enamels are those described in WO 2009/043796 (the content of which is incorporated by reference in the present application). These enamels contain silicon, oxygen and calcium, and preferably, potassium and titanium as well; they most preferably have:

- a low content of calcium; and/or

- a high content of potassium; and/or

- a low content of titanium.

The examples hereafter are intended to illustrate the invention without however limiting the scope thereof.

General experimental procedure used for the examples: Hydrochlorination reactions were performed in a glass reactor equipped at the bottom with a sintered glass disk to obtain a good dispersion of the gaseous reactants composed of acetylene and hydrochloric acid.

The thermal control of the system was obtained by a double wall reactor with a thermal oil regulation to maintain the desired temperature controlled by a thermowell placed in the reactor itself.

The gaseous flow rate was of 5 Nl/hour for C2H2 and 6 Nl/hour for HC1. The residence time calculated for an "empty" reactor (only loaded with the ionic liquid) at 150°C and atmospheric pressure was 3.2 s.

Small samples of the materials to be evaluated were immersed in the medium and analyzed.

SS (stainless steel) 316L samples remained practically unaffected by butyl- methylimidazolium (BMIM) chloride alone after 7 h at 150°C, but in the presence of said imidazolium, HC1 and C2H2 (hydrochlorination medium), a devastating corrosion was already observed after ½ hour. The same applies to zirconium and silver, the latter even completely dissolving in the medium.

On the other side, after 554h with the same reaction medium (imidazolium, HC1 and C2H2), enameled steel remained unaffected. Remained also not or insignificantly affected in the same conditions, HYFLON® (0.0%), PEEK (0.0%), ECTFE (-0.3%) and PTFE (0.0%) after 216h; ETFE (0.0%) after 186h; FEP (0.0%) after 139.5h; graphite impregnated with PTFE (0.0%) after 210h and with a phenolic resin (0.0%) after 161h; alumina (0.0%) after 210h; niobium (- 0.6%) after 164h; tantalum (0.0%) after 142h; platinum (-0.1%) after 158.5h and silicon carbide (0.0%) after 180.5h, the figures in () indicating the weight change after the indicated soaking period.

PP homopolymer and CPVC were tested in the same conditions, but at a lower temperature (90°C) and they seemed to perform well and show little weight change after 186h (respectively - 0.2% and + 0.1 %).

Other polymers/resins, were also tested, still in the same conditions, with the following results:

Derakane 470 @ 150°C / 118h (+0.7%)

Kera SP 30 @ 100°C / 40.5h (-0.2%)

Covidur 883 @ 90°C / 187h (+0.9%)

Vulco 2190 @ 90°C / 162h (+0.9%)

HB2 @ 100°C / 163.5h (0%)HC276 @ 90°C / 163.5h (0%). Besides, some among the above tested materials quite surprisingly raised the conversion rate versus the one obtained in the glass reactor, namely: PTFE, graphite impregnated with PTFE or with a phenolic resin and tantalum.

Claims

C L A I M S

1 - Process for the hydrohalogenation of an alkyne in the presence of a catalytic system comprising at least one ionic liquid comprising at least one non- protonated cation, according to which said process is at least partly carried out in apparatus made from or covered with materials which are resistant to

halogenated acids in dissociated form and which are chosen from metals, polymers, ceramics, refractory materials, (impregnated) graphite and enamel.

2 - Process according to the preceding claim, wherein the alkyne is acetylene and the halogenated acid is HC1.

3 - Process according to the preceding claim, wherein the

hydrochlorination reaction is carried out at a temperature in the range of from room temperature to 220°C.

4 - Process according to any of the preceding claims, wherein the non- protonated cation is selected from quaternary ammonium cations, phosphonium cations, imidazolium cations, pyridinium cations and pyrrolidinium cations.

5 - Process according to any of the preceding claims, wherein the ionic liquid acts as a solvent so that no further solvent is used.

6 - Process according to any of the preceding claims, wherein the catalytic system consists essentially of at least one ionic liquid comprising at least one non-protonated cation and at least one anion selected from chloride and methanesulfonate.

7 - Process according to the preceding claim, wherein the ionic liquid is selected from phosphonium chlorides, phosphonium methanesulfonates, imidazolium chlorides and imidazolium methanesulfonates.

8 - Process according to the preceding claim, wherein the ionic liquid is selected from l-butyl-3-methylimidazolium chloride,

trihexyltetradecylphosphonium chloride, 1 -ethyl-3 -methylimidazolium methanesulfonate, l-methyl-3-octylimidazolium chloride, 1 -Ethyl-3 - methylimidazolium chloride and l-benzyl-3 -methylimidazolium chloride. 9 - Process according to any of claims 1 to 5, wherein the catalytic system comprises: a) at least one N-alkylated imidazole and/or the corresponding imidazolium; and b) optionally at least one compound of at least one metal.

10 - Process according to the preceding claim, wherein the N-alkylated imidazole is defined by formula (I) here below

11 - Process according to the preceding claim, wherein the N-alkylated imidazole is selected from 1-methylimidazole, 1-ethylimidazole and 1- butylimidazole.

12 - Process according to any of claims 9 to 11, wherein the catalytic system comprises: a) at least one N-alkylated imidazole and/or the corresponding imidazolium; and b) at least one compound of at least one metal chosen from Pd, Pt, Au, Hg, Ru and Os.

13 - Process according to any of claims 1 to 45, wherein the catalytic system comprises a mixture of: a) at least one compound of at least one metal one of which being chosen from palladium, platinum and osmium; and b) at least one ionic liquid comprising at least one non-protonated cation and at least one anion ; the mixture being chosen from the group of the mixtures comprising when the metal is palladium, palladium (II) acetate and l-butyl-3 -methylimidazolium chloride or l-ethyl-3 - methylimidazolium chloride, palladium (II) chloride, copper chloride and l-butyl-3 -methylimidazolium chloride, palladium (II) chloride, cuprous chloride and l-butyl-3 -methylimidazolium chloride, palladium (II) chloride and l-ethyl-3 -methylimidazolium chloride, 1-methyl- 3-octylimidazolium chloride, l-benzyl-3 -methylimidazolium chloride, trihexyltetradecylphosphonium chloride or l-butyl-4-methylpyridinium bis(trifluoromethylsulfonyl)imide, palladium (II) chloride, palladium (II) acetate and l-butyl-4- methylpyridinium bis(trifluoromethylsulfonyl)imide; when the metal is platinum, platinum (II) chloride and l-butyl-3 -methylimidazolium chloride, l-butyl-3 - methylimidazolium tetrachloroferrate, l-ethyl-3 -methylimidazolium chloride, l-ethyl-3 -methylimidazolium methanesulfonate, l-ethyl-3 - methylimidazolium tetrafluorethyl sulfonate, l-methyl-3-octylimidazolium chloride, l-methyl-3-octylimidazolium triflate or

trihexyltetradecylphosphonium chloride, platinum (IV) chloride and l-ethyl-3 -methylimidazolium triflate or trihexyltetradecylphosphonium bis(trifluoromethylsulfonyl)imide, potassium hexachloroplatinate (IV) and l-ethyl-3 -methylimidazolium triflate; and when the metal is osmium, osmium (III) chloride and l-butyl-3-methylimidazolium chloride, l-ethyl-3- methylimidazolium tetrafluorethyl sulfonate, l-methyl-3-octylimidazolium chloride or trihexyltetradecylphosphonium chloride.

14 - Process according to any of claims 1 to 5, wherein the catalytic system comprises an imidazolium-based ionic liquid with chloride, bromide,

hexafluorophosphate or tetrafluorophosphate ion as anion and one or more of gold, platinum, palladium, tin, mercury, copper or rhodium chlorides.

15 - Process according to any of the preceding claims, said process being at least partly carried out in apparatus made from enamelled steel. 16 - Process according to the preceding claim, wherein said enamel contains silicon, oxygen, calcium, potassium and titanium and has:

- a low content of calcium; and/or

- a high content of potassium; and/or

- a low content of titanium. 17 - Process according to any of claims 1 to 14, said process being at least partly carried out in apparatus made from or covered with tantalum, platinum or niobium.

18 - Process according to any of claims 1 to 14, said process being at least partly carried out in apparatus made from or covered with tantalum. 19 - Process according to any of claims 1 to 14, said process being at least partly carried out in apparatus made from or covered with silicon carbide, alumina or (impregnated) graphite.

20 - Process according to any of claims 1 to 14, said process being at least partly carried out in apparatus made from or covered with PEEK or a fluorinated polymer.

21 - Process according to any of claims 1 to 14, said process being at least partly carried out in apparatus made from or covered with PP (or polypropylene) homopolymer or CPVC (of chlorinated PVC). 22 - Process according to any of claims 1 to 14, said process being at least partly carried out in apparatus made from or covered with PTFE, graphite impregnated with PTFE or with a phenolic resin, or tantalum.