WO2008037657A1

WO2008037657A1 - Process for the preparation of halogenated hydrocarbons with at least 3 carbon atoms in the presence of a ruthenium compound

Info

Publication number: WO2008037657A1
Application number: PCT/EP2007/060014
Authority: WO
Inventors: Johannes Eicher; Ercan Uenveren; Véronique Mathieu
Original assignee: Solvay (Société Anonyme)
Priority date: 2006-09-26
Filing date: 2007-09-21
Publication date: 2008-04-03

Abstract

A telomerisation process is described whereby haloalkanes like tetrachloromethane are added to halogensubstituted olefins like 2-chloroprop-1- ene in the presence of a Ru catalyst. The reaction products, e.g. 1,1,1,3,3-pentachlorobutane, can be fluorinated.

Description

PROCESS FOR THE PREPARATION OF HALOGENATED HYDROCARBONS WITH AT LEAST 3 CARBON ATOMS IN THE PRESENCE OF A RUTHENIUM COMPOUND

The instant invention concerns a process for the preparation of halogenated hydrocarbons comprising at least 3 carbon atoms by catalytic reaction between a haloalkane and an olefin.

Halogenated hydrocarbons can be prepared by the addition of haloalkanes 5 to olefins.

EP-A-O 787707 (US-A 5917098) discloses the preparation of 1,1,1,3,3-pentachlorobutane from tetrachloromethane and 2-chloro-prop-l-ene in the presence of a copper halide and certain amines.

WO 98/50330 (US-A 6399839) discloses the preparation of chloroalkanes 10 or chlorofluoroalkanes by the addition of haloalkanes, such as tetrachloromethane, 1,1,1-trichloroethane or l,l,l-trichloro-2,2,2-trifluoroethane to olefins which may contain halogen atoms. In that process, an organically substituted copper compound is used as catalyst; a polar solvent and/or a cocatalyst selected among amines, amides and trialkyl phosphinoxides. 15 Especially preferred compounds to be prepared are 1,1,1,3,3-pentachlorobutane and 1,1,1 ,3 ,3-pentachloropropane.

WO 98/50329 (US-A 6399840) discloses the preparation of 1,1,1,3,3-pentachlorobutane from tetrachloromethane and 2-chloroprop-l-ene in the presence of a copper (I) or copper (II) catalyst.

20 WO 97/07083 (US-A 5902914) discloses a process for the preparation of halogenated hydrocarbons by the addition of haloalkanes to olefins in the presence of copper chloride and t-butylamine as cocatalyst.

Object of the present invention is to provide a process for the preparation of halogenated hydrocarbons applying novel catalysts.

25 This object and other objects are achieved by the process of the present invention.

The present invention concerns a process for the preparation of halogenated hydrocarbons with at least 3 carbon atoms by the reaction of a haloalkane and an olefin substituted by at least one halogen atom in the presence 30 of a ruthenium containing catalyst. Preferably, ruthenium is present in the form of a ruthenium (Ru) compound. The term "Ru compound" preferably denotes complex salts of Ru(II). The term "complex" denotes in the context of the present invention that, besides anions neutralizing the two positive charges of the Ru (II) cation, also neutral ligands are bound to the cation.

Complex compounds of Ru (II) comprising inorganic and/or organic anions can be applied. Preferred inorganic anions are halide anions, especially chloride. In principle, the anions of other inorganic acids can be comprised, e.g. sulfate anions, nitrate anions, or phosphate anions. Examples for organic anions are the anions of organic acids like acetic acid or propionic acid.

The complex Ru compounds comprise a neutral ligand which coordinates to the Ru (II) cation. Preferred type of ligands are substituted phosphines which comprise no P-H bond. Phosphines substituted by 3 groups which may be identical or different and are selected from aliphatic and aromatic groups are preferred. Preferred groups are selected from linear or branched Cl to C 8 alkyl groups and the phenyl group. Triphenylphosphine is an especially preferred ligand.

Preferred catalysts are halogen and phosphine substituted complexes.

Tris-(triphenylphosphine) ruthenium (II) halide, especially tris- (triphenylphosphine) ruthenium (II) chloride, RuCl2(PPh3)3, is highly suitable as a catalyst in the present invention. The haloalkanes which are used in the process of the present invention generally are saturated organic compounds. Preferably, they have one to three carbon atoms. Preferably, they are substituted by at least two chlorine atoms. They may be substituted by other halogen atoms or by alkyl or halogenoalkyl groups. Examples of suitable haloalkanes are dichloromethane, trichloromethane, tetrachloromethane, 1,1,1-trichloroethane and chlorofluoroethanes like l,l,l-trichloro-3,3,3-trifluoroethane, 1,1-dichloro-l- fluoroethane (HCFC-HIb) and l-chloro-l,l-difiuoroethane (HCFC-142b). Tetrachloromethane is especially preferred.

The olefin which is used as starting material in the process of the present invention is generally ethylene, propylene or a butene, each of which are substituted by at least one halogen atom, and optionally also by one or more alkyl groups, halogenoalkyl groups, nitril (CN) groups or carboxylic acid groups (COOH). Halogenated olefins are preferred. Chlorinated olefins are very suitable. Generally, they correspond to the formula R!R2C=CC1CR3. In this formula, RI , R^ and R^ independently represent H or Cl, linear, branched or cyclic alkyl or alkenyl, an aryl or a heteroaryl group. These alkyl, alkenyl, aryl or heteroaryl groups may be substituted. Examples for such halogenated olefins are vinyl chloride, vinylidene chloride, trichloroethylene, the isomers of chloropropene like 1-chloroprop-l-ene, 2-chloroprop-l-ene, and 3-chloroprop-l- ene. 2-chloroprop-l-ene is especially preferred. If chlorofluoroalkanes like HCFC-141b or HCFC-142b are used as haloalkanes, chlorofluoroalkanes are obtained as reaction product.

The halogenated hydrocarbons obtained by the process of the present invention preferably belong to the family of chloropropanes, chlorobutanes and chloropentanes or, if a fluorine-containing alkane or alkene is applied as starting material, to the family of chlorofluoropropanes, chlorofluorobutanes or chlorofluoropentanes. The carbon atoms of the chloropropanes, chlorobutanes and chloropentanes (or respective fluorine-containing compounds as mentioned above) can be substituted by other functional groups like other halogen atoms (e.g. bromine or iodine), alkyl groups, halogenoalkyl groups, nitrile (CN) groups or carboxylic acid groups (COOH). Chloropropanes, chlorobutanes and chloropentanes not substituted by such other functional groups are preferred. Halogenated hydrocarbons of the general formula C_nH(2n+2)-pClp are especially preferred reaction products. In this formula, n is an integer and stands for 3 or 4, p is an integer and stands for 3, 4, 5, 6 or 7. Examples of compounds which can be produced by the process of the present invention are 1,1,1 ,3 ,3-pentachloropropane, 1,1,1 ,3 ,3-pentachlorobutane, 1,1,1 ,3-tetrachloropropane, 1 , 1 ,3,3-tetrachlorobutane, 1,1,1 ,3 ,3 ,3-hexachloropropane and 1 , 1 -dichloro-2-trichloromethylpropane. 1,1,1,3,3-pentachlorobutane and 1,1,1,3,3-pentachloropropane are preferred. In a discontinuous process, the molar ratio between catalyst and olefin often is greater than or equal to 0.0005. Advantageously, it is equal to or greater than 0.001. Preferably, it is equal to or greater than 0.003. Often, the molar ratio between catalyst and olefin is lower than or equal to 1. Advantageously, it is lower than or equal to 0.5. Preferably, it is lower than or equal to 0.1. In a continuous process, the molar ratio between catalyst and the olefin should lie in the range given above for a discontinuous process, but it may reach higher upper limits, e.g. it could be up to 10; here, the upper limit is preferably lower than or equal to 1.

The amount of catalyst is expressed in a discontinuous process relative to the initial concentration of the olefin. In a continuous process, it is relative to the stationary concentration of the olefin in the reactor. If desired, a solvent can be present during the reaction. Preferred solvents are aprotic. The haloalkane e.g. tetrachloromethane, may be used in excess and function as a reactant and as a solvent. If desired, the reaction products may be used as a solvent. Toluol is another suitable solvent, as well as hydrofluorocarbons like 1,1,1,3,3-pentafluorobutane.

The molar ratio between haloalkane, e.g. tetrachloromethane, and the olefin, e.g. 2-chloroprop-l-ene, can vary in a broad range. In general, the ratio is equal to or greater than 0.1. Advantageously, it is equal to or greater than 0.5. Preferably, it is equal to or greater than 1. Generally, the ratio is equal to or lower than 20. Advantageously, it is equal to or lower than 10. Preferably, it equal to or lower than 8. In case of such high ratios, the haloalkane also serves as a solvent.

Generally, the reaction is performed above ambient temperature. Preferably, the temperature is equal to or higher than 40⁰C. Generally, the temperature is equal to or lower than 150⁰C. A preferred range for the reaction temperature is from 40 to 120⁰C. Advantageously, the reaction temperature is higher than or equal to 50⁰C. Preferably, it is higher than or equal to 60⁰C. Advantageously, it is lower than or equal to 120⁰C. A most preferred range is 90⁰C to 110⁰C. The reaction can be performed with good results at even lower temperatures, for example, at temperatures equal to or lower than 100⁰C.

The reaction time in a discontinuous process or the residence time in a continuous process is dependent from parameters such as reaction temperature, catalyst concentration, concentration of the starting materials and the molar ratio of the components in the reaction mixture. Generally, the reaction time or residence time can vary from 5 seconds to 20 hours.

The pressure in the reactor is usually equal to or greater than ambient pressure. It is usually lower than or equal to 15 bars (abs.), preferably lower than or equal to 10 bars.

In principle, any catalyst or catalytic system known to be active for the process according to the present invention might be used as cocatalyst. It is preferred that the Ru catalyst described above is the only catalyst used in the process.

If desired, the process can be performed in the presence of a phase transfer catalyst. Phase transfer catalysts are principally known. Ammonium, phosphonium and arsonium based transfer catalysts are very suitable. For example, tetraalkylammonium or benzyltrialkylammonium or tetraalkylphosphonium halides, hydrogen sulfates, thiocyanates or tetrafluoroborates are applicable. The alkyl groups can be the same or different. Alkyl denotes preferably Cl to C20 alkyl like methyl, ethyl, butyl, octyl, hexadecyl or octadecyl. Tetrabutylphosphonium chloride is a very suitable phase transfer catalyst. Also, the corresponding arsonium compounds are suitable phase transfer catalysts. Other suitable phase transfer catalysts are crown ethers. The molar ratio between Ru catalyst and phase transfer catalyst preferably is lower than or equal to 10:1, more preferably lower than or equal to 5 : 1. It is preferably higher than or equal to 0.1 : 1 , still more preferably higher than or equal to 0.2: 1. Often, the ratio between Ru catalyst and phase transfer catalyst lies in a range of 0.5 : 1 and 2:1.

The process according to the present invention allows for the preparation of halogenated alkanes in an efficient manner. The alkanes produced are especially suitable as intermediates in chemical synthesis. For example, they can be fluorinated. The fluorinated products are useful, for example, as solvents, refrigerants or blowing agents. A part or, preferably, all of the chlorine atoms are substituted by fluorine atoms. The fluorination can be easily accomplished by reacting the halogenoalkanes obtained by the process of the present invention with HF which advantageously is anhydrous. The chlorine- fluorine exchange can be performed with or without added fluorination catalyst. Suitable fluorination catalysts are salts of antimony, salts of titanium, salts of tantalum or salts of tin. The halide salts, especially the fluorides, chlorides or chlorofluorides are preferred salts. Other suitable fluorination catalysts are compounds of chromium, aluminium and zirconium; the oxides are preferred compounds for catalyzing fluorination reactions.

Specific examples of hydro fluorocarbons have the general formula C_nH(2_n+2)-pF_p. In this formula, n is an integer and is 3 or 4, and p is an integer and is 3, 4, 5, 6 or 7. Especially preferred hydrofluorocarbons are 1,1,1,3,3-pentafluoropropane, 1,1,1,3,3,3-hexafluoropropane and most preferred 1,1,1,3,3-pentafluorobutane.

According to a very preferred embodiment of the present invention, 1,1,1,3,3-pentafluorobutane is prepared in a first step by addition of tetrachloromethane to 2-chloroprop-l-ene to form 1,1,1,3,3-pentachlorobutane as intermediate. This intermediate is then reacted with HF, in the presence or absence of a catalyst, in a second step to yield 1,1,1,3,3-pentafluorobutane. Catalysts which can be applied advantageously are for example, salts of antimony, salts of titanium, salts of tantalum or salts of tin.

The following examples are intended to explain the invention further without limiting it. Example 1 :

2-chloroprop-l-ene (11 g; 0.14 moles), tetrachloromethane (65 g; 0.4 moles) and RuCl2(PPh3)2 (3,3 g; 0,003 moles) were mixed in a stainless steel autoclave in the presence of phase transfer catalyst PPt^Cl (1,2 g; 0,003 moles). The mixture was heated (up to 100⁰C, pressure: 3 bar). At the outcome of the reaction (after 5 h), 1,1,1,3,3-pentachlorobutane was obtained (5,5 GC %). Example 2 :

2-chloroprop-l-ene and tetrachloromethane (molar ratio: 1 :1.8) and RuCl2(PPh3)2 (molar ratio between 2-chloroprop-l-ene and the catalyst 1 :0.008) was kept for 13 hours at a temperature of 130⁰C. Conversion of 2-chloroprop-l- ene was 40 %, selectivity to 1,1,1,3,3-pentafluorobutane was 68 %. Example 3 : 2-chloropropene, tetrachloromethane and RuCl2(PPh3)3 were mixed in a flask in the presence of phase transfer catalyst. The mixture was heated in the preferred temperature range. At the outcome of the reaction, 1,1,1,3,3-pentachlorobutane was obtained.

Claims

C L A I M S

1. Process for the preparation of halogenated hydrocarbons with at least

3 carbon atoms by the reaction of a haloalkane and an olefin which is substituted by at least one halogen atom, in the presence of a ruthenium containing catalyst, whereby ruthenium preferably is comprised in the form of a ruthenium (Ru) compound.

2. Process according claim 1 wherein the reaction is performed in the presence of a phase transfer catalyst.

3. Process according to claim 1 or 2 wherein the olefin corresponds to the formula R¹ R²C=CClCR³ wherein R¹ , R² and R³ independently represent H or Cl, linear, branched or cyclic alkyl or alkenyl, an aryl or a heteroaryl group, whereby the alkyl, alkenyl, aryl or heteroaryl groups may be substituted.

4. Process according to claim 3 wherein the olefin is selected from the group consisting of vinyl chloride, vinylidene chloride, trichloroethylene, and the isomers of chloropropene like 1 -chloroprop- 1 -ene, 2-chloroprop- 1 -ene, and 3-chloroprop-l-ene.

5. Process according to one of the preceding claims wherein the haloalkane has one to three carbon atoms and is substituted by at least two chlorine atoms and is optionally substituted by other halogen atoms or by alkyl or halogenoalkyl groups.

6. Process according to claim 5 wherein the haloalkane is selected from the group consisting of dichloromethane, trichloromethane, tetrachloromethane, 1,1,1-trichloroethane and l,l,l-trichloro-3,3,3-trifluoroethane.

7. Process according to claim 1 wherein the Ru compound is selected from Ru (II) complexes.

8. Process according to claim 7 wherein a Ru (II) dihalide is used which is complexed by phosphine ligands.

9. Process according to claim 8 wherein the phosphine ligand is selected from phosphines substituted by three groups which may be the same or different and which are selected from Cl to C8 alkyl and aryl groups.

10. Process according to any of claims 7, 8 or 9 wherein RuCl2(PPh3)2 is used as catalyst.

11. Process for the preparation of hydro fluorocarbons wherein a halogenated hydrocarbon prepared according to any one of claims 1 to 10 is fluorinated.