1,3-BUTADIENE SYNTHESIS

Abstract

The invention relates to a process for preparing 1,3-butadiene by means of ene-yne metathesis over at least one transition metal catalyst of the element ruthenium.

Claims

1. A process for preparing 1,3-butadiene, the process comprising contacting ethene and ethyne in the presence of at least one transition metal catalyst of the element ruthenium.

2. The process as claimed in claim 1, the contacting is carried out in liquid phase using at least one solvent.

3. The process as claimed in claim 2, wherein the solvent is a haloalkane which is liquid at room temperature, preferably dichloromethane.

4. The process as claimed in claim 1, wherein the contacting is carried out at a temperature of −70 to 50° C.

5. The process as claimed in claim 1, wherein the contacting is carried out without superatmospheric pressure.

6. The process as claimed in claim 1, wherein the at least one transition metal catalyst comprises at least one transition metal catalyst of the general formula (A), ##STR00005## wherein: the radicals L are identical or different ligands, preferably uncharged electron donors, and the radicals R are identical or different and are each hydrogen, alkyl, cycloalkyl, alkenyl, alkynyl, aryl, carboxylate, alkoxy, alkenyloxy, alkynyloxy, aryloxy, alkoxycarbonyl, alkylamino, alkylthio, arylthio, alkylsulfonyl or alkylsulfinyl, where these radicals can each optionally be substituted by one or more alkyl, halogen, alkoxy, aryl or heteroaryl radicals, or, as an alternative, the two radicals R are bridged with inclusion of the common carbon atom to which they are bound to form a cyclic group which can be aliphatic or aromatic in nature and is optionally substituted and can contain one or more heteroatoms.

7. The process as claimed in claim 6, wherein: R is, in each case, independently of one another, hydrogen, C.sub.1-C.sub.30-alkyl, C.sub.3-C.sub.20-cycloalkyl, C.sub.2-C.sub.20-alkenyl, C.sub.2-C.sub.20-alkynyl, C.sub.6-C.sub.24-aryl, C.sub.1-C.sub.20-carboxylate, C.sub.1-C.sub.2D-alkoxy, C.sub.2-C.sub.20-alkenyloxy, C.sub.2-C.sub.20-alkynyloxy, C.sub.2-C.sub.24-aryloxy, C.sub.2-C.sub.20-alkoxycarbonyl, C.sub.1-C.sub.30-alkylamino, C.sub.1-C.sub.30-alkylthio, C.sub.6-C.sub.24-arylthio, C.sub.1-C.sub.20-alkylsulfonyl or C.sub.1-C.sub.20-alkylsulfinyl, where these radicals can, in each case, optionally be substituted by one or more C.sub.1-C.sub.6-alkyl, halogen, C.sub.1-C.sub.6-alkoxy, preferably i-propoxy, aryl, preferably phenyl, or heteroaryl radicals, or, as an alternative, the two radicals R are bridged with inclusion of the common carbon atom to which they are bound to form a cyclic group which can be aliphatic or aromatic in nature and is optionally substituted and can contain one or more heteroatoms; and L is, in each case, independently of one another, a phosphine, sulfonated phosphine, phosphate, phosphinite, phosphonite, ether, amine, amide, sulfoxide, carboxyl, nitrosyl, pyridine, thioether or imidazolidine.

8. The process as claimed in claim 1, wherein the at least one transition metal catalyst is selected from the group consisting of: M1=benzylidene[1,3-bis(2,4,6-trimethylphenyl)-2-imidazolidinylidene]dichloro(tricyclohexylphosphine)ruthenium, M2=bis(tricyclohexylphosphine)[(phenylthio)methylene]ruthenium(II) dichloride, M3=1,3-bis(2,4,6-trimethylphenyl)-4,5-dihydroimidazol-2-ylidene[2-(i-propoxy)-5-(N,N-di-MeNH.sub.2SO.sub.2)phenyl]methyleneruthenium(II) dichloride, M4=bis(tricyclohexylphosphine)-3-phenyl-1H-inden-1-ylideneruthenium(II) dichloride, M5=benzylidenebis(tricyclohexylphosphine)dichlororuthenium, M6=dichloro(o-isopropoxyphenylmethylene)-(tricyclohexylphosphine)ruthenium(II), M7=(1,3-bis(2,4,6-trimethylphenyl)-2-imidazolidinylidene)dichloro(o-isopropoxyphenyl methylene)ruthenium, M8=tricyclohexylphosphine[4,5-dimethyl-1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene][2-thienylmethylene]ruthenium(II) dichloride, M9=tricyclohexylphosphine[1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene][3-phenyl-1H-inden-1-ylidene]ruthenium(II) dichloride, M10=[1,3-bis(2,6-di-i-propylphenyl)-4,5-dihydroimidazol-2-ylidene]-[2-i-propoxy-5-(trifluoroacetamido)phenyl]methyleneruthenium(II) dichloride, M11=tri(i-propoxy)phosphine(3-phenyl-1H-inden-1-ylidene)[1,3-bis(2,4,6-trimethyl phenyl)-4,5-dihydroimidazol-2-ylidene]ruthenium(II) dichloride, M12=tricyclohexylphosphine[1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene][2-thienyl methylene]ruthenium(II) dichloride, M13=3-phenyl-1H-inden-1-ylidene[bis(i-butylphobane)]ruthenium(II) dichloride, M14=dichloro[1,3-bis(2-methylphenyl)-2-imidazolindinylidene](benzylidene) (tricyclohexyl phosphine)ruthenium(II), M15=dichloro[1,3-bis(2-methylphenyl)-2-imidazolindinylidene](2-isopropoxyphenyl methylene)ruthenium(II).

9. The process as claimed in claim 8, wherein the at least one transition metal catalyst comprises at least M5.

10. The process as claimed in claim 1, wherein the at least one catalyst is present in the reaction mixture in an amount of 0.01 to 10,000 mol %, calculated as sum of all catalysts used and based on the amount of ethene used.

11. The process as claimed in claim 1, wherein the process is carried out batchwise.

12. (canceled)

13. The process as claimed in claim 2, wherein the ethene and ethyne are in the form of a gas mixture at a ratio of 6:4 to 4:6, and are fed as a gas stream into contact with the liquid phase of catalyst and solvent.

14. The process as claimed in claim 1, wherein: the contacting is carried out in liquid phase using at least one haloalkane solvent in which the solvent is soluble and which is liquid at room temperature; the contacting is carried out at ambient pressure and a temperature of −70 to 50° C.; the ethene and ethyne are in the form of a gas mixture at a ratio of 6:4 to 4:6, and are fed as a gas stream into contact with the liquid phase of catalyst and solvent the at least one transition metal catalyst comprises at least one transition metal catalyst of the general formula (A), ##STR00006## wherein: the radicals L are identical or different ligands, selected from the group consisting of: a C.sub.6-C.sub.24-arylphosphine, C.sub.1-C.sub.10-alkylphosphine or C.sub.3-C.sub.20-cycloalkylphosphine ligand, a sulfonated C.sub.6-C.sub.24-arylphosphine or sulfonated C.sub.1-C.sub.10-alkylphosphine ligand, a C.sub.6-C.sub.24-arylphosphinite or C.sub.1-C.sub.10-alkylphosphinite ligand, a C.sub.6-C.sub.24-arylphosphonite or C.sub.1-C.sub.10-alkylphosphonite ligand, a C.sub.6-C.sub.26-arylphosphite or C.sub.1-C.sub.10-alkylphosphite ligand, a C.sub.6-C.sub.24-arylarsine or C.sub.1-C.sub.10-alkylarsine ligand, a C.sub.6-C.sub.24-arylamine or C.sub.1-C.sub.10-alkylamine ligand, a pyridine ligand, a C.sub.6-C.sub.24-aryl sulfoxide or C.sub.1-C.sub.10-alkyl sulfoxide ligand, a C.sub.6-C.sub.24-aryl ether or C.sub.1-C.sub.10-alkyl ether ligand or a C.sub.6-C.sub.24-arylamide or C.sub.1-C.sub.10-alkylamide ligand, each of which can be substituted by a phenyl group which in turn is optionally substituted by a halogen, C.sub.1-C.sub.5-alkyl or C.sub.1-C.sub.5-alkoxy radical, or L is an oxygen atom of a substituent R which is coordinated to the ruthenium, and the radicals R are identical or different, and are each hydrogen, C.sub.1-C.sub.30-alkyl, C.sub.3-C.sub.20-cycloalkyl, C.sub.2-C.sub.20-alkenyl, C.sub.2-C.sub.20-alkynyl, C.sub.6-C.sub.24-aryl, C.sub.1-C.sub.20-carboxylate, C.sub.1-C.sub.20-alkoxy, C.sub.2-C.sub.20-alkenyloxy, C.sub.2-C.sub.20-alkynyloxy, C.sub.6-C.sub.24-aryloxy, C.sub.2-C.sub.20-alkoxycarbonyl, C.sub.1-C.sub.30-alkylamino, C.sub.1-C.sub.30-alkylthio, C.sub.6-C.sub.24-arylthio, C.sub.1-C.sub.20-alkylsulfonyl or C.sub.1-C.sub.20-alkylsulfinyl, where these radicals can, in each case, optionally be substituted by one or more C.sub.1-C.sub.6-alkyl, halogen, C.sub.1-C.sub.6-alkoxy, or, as an alternative, the two radicals R are bridged with inclusion of the common carbon atom to which they are bound to form a cyclic group which can be aliphatic or aromatic in nature and is optionally substituted and can contain one or more heteroatoms.

Description

APPARATUS

[0090] FIG. 1 shows, by way of example, an apparatus as was used for the experiments within the framework of the present invention. The reference numerals in FIG. 1 have the following meanings: [0091] 1 ethyne [0092] 2 H.sub.2SO.sub.4 (95%-98%) [0093] 3 2 N NaOH [0094] 4 molecular sieve 4 Å (Sigma Aldrich) [0095] 5 ethene [0096] 6 protective gas N.sub.2 [0097] 7 bubble counter [0098] 8 cryostat −20° C. [0099] 9 heating bath [0100] 10 low-temperature cooler [0101] 11 reactor 1, 250 ml, glass [0102] 12 septum [0103] 13 reactor 2, 250 ml, glass [0104] 14 about 100 mbar gauge [0105] exhaust air

[0106] The experimental apparatus consisted of two reactors (250 ml three-necked glass flask) provided with magnetic stirrer bar, two low-temperature coolers (cooling liquid maintained at −20° C.), two septi for sampling and two oil baths as heating bath. The gas mixture composed of previously purified ethyne (first 95-98% strength H.sub.2SO.sub.4 then 2 N NaOH and finally molecular sieve) and ethene was firstly introduced into a first reactor below the surface of the liquid via a glass capillary having a diameter in the range from 1.5 to 7 mm. The proportion of this gas mixture which was not consumed by the reaction or condensed in the low-temperature cooler of reactor 1 was in turn conveyed via a further capillary into a second reactor underneath the surface of the liquid. After passage through the second low-temperature cooler, the proportions of the gas mixture which had not been reacted or not condensed in the low-temperature cooler of reactor 2 went into the exhaust air.

[0107] The liquid contents of reactor 1 and reactor 2 were analyzed by means of GC (gas chromatography). Owing to the low conversions, the evaluation was only qualitative. However, the presence of the reference substance cyclohexane allowed the amount of butadiene formed to be compared by means of the peak area ratio of butadiene to cyclohexane for the experiments within the framework of the present invention.

[0108] Table 1 shows the substances found with their respective retention times. Identification was effected by comparison with commercial pure substances or by means of GC-MS (MS=mass spectrometry).

TABLE-US-00001 TABLE 1 Retention time/min Substance 2.08 ethene, ethyne, air 2.26 1,3-butadiene 2.69 trans-1,3-pentadiene 2.75 cis-1,3-pentadiene 2.88 dichloromethane 3.64 cyclohexane 4.14; 4.35; 4.37 2,4-hexadiene isomers 4.70 benzene 7.01 toluene 8.94 octatetraene 9.25 styrene

Comparative Example 1 (without Catalyst)

[0109] 50 ml of dichloromethane were brought to 30° C. under protective gas in a 100 ml glass vessel filled with low-temperature cooler (temperature of the cooling medium −20° C.) which had previously been made inert by means of N.sub.2. Making spaces inert refers to the procedure of displacing the atmospheric oxygen or reactive or explosive gases or gas mixtures from spaces by introduction of inert gases or vapors. In addition, 1.0 ml of cyclohexane was added as reference to the dichloromethane. A mixture of ethene and ethyne in a ratio of 1:1 was subsequently passed into the solvent while stirring during the entire reaction time, with samples being taken from the liquid phase at regular intervals. No butadiene was formed.

Comparative Example 2 (M4, without Ethene)

[0110] 50 mg of catalyst M4, dissolved in 50 ml of dichloromethane, were brought to 30° C. under protective gas in a vessel with low-temperature cooler (temperature of the cooling medium −20° C.) which had previously been made inert by means of N.sub.2. In addition, 1.0 ml of cyclohexane were added as reference. Ethyne was subsequently introduced while stirring during the entire reaction time and samples were taken from the liquid phase at regular intervals. No butadiene was formed.

Comparative Example 3 (M5, Without Ethene)

[0111] 50 mg of catalyst M5, dissolved in 50 ml of dichloromethane, were brought to 30° C. under protective gas in a vessel with low-temperature cooler (temperature of the cooling medium −20° C.) which had previously been made inert. In addition, 1.0 ml of cyclohexane were added as reference. Ethyne was subsequently introduced while stirring during the entire reaction time and samples were taken from the liquid phase at regular intervals. No butadiene was formed.

Example 1

[0112] 50 mg of catalyst MX, where MX is in each case one of the abovementioned catalysts M1 to MIS, dissolved in 50 ml of dichloromethane, were brought to 30° C. under protective gas (N.sub.2) in a vessel with low-temperature cooler (temperature of the cooling medium −20° C.) which had previously been made inert by means of N.sub.2. In addition, 1.0 ml of cyclohexane were added as reference. A mixture of ethene and ethyne in a ratio of 1:1 was subsequently introduced into the solvent underneath the surface of the liquid while stirring during the entire reaction time. Samples were taken from the liquid phase at regular intervals during the reaction time. Butadiene was detected by gas chromatography in these samples.

Example 2 (M5, −64° C.)

[0113] 50 mg of catalyst M5, dissolved in 50 ml of dichloromethane, were brought to −64° C. under protective gas in a vessel with low-temperature cooler (temperature of the cooling medium −20° C.) which had previously been made inert by means of N.sub.2. In addition, 1.0 ml of cyclohexane was added as reference. A mixture of ethene and ethyne in a ratio of 1:1 was subsequently introduced while stirring during the entire reaction time. Samples were taken from the liquid phase at regular intervals during the reaction time. Butadiene was detected by gas chromatography in these samples.

Example 3 (M5, Double the Amount of Catalyst)

[0114] 100 mg of catalyst M5, dissolved in 50 ml of dichloromethane, were brought to 30° C. under protective gas (N.sub.2) in a vessel with low-temperature cooler (temperature of the cooling medium −20° C.) which had previously been made inert by means of N_. In addition, 1.0 ml of cyclohexane was added as reference. A mixture of ethene and ethyne in a ratio of 1:1 was subsequently introduced while stirring during the entire reaction time. Samples were taken from the liquid phase at regular intervals during the reaction time. Butadiene was detected by gas chromatography in these samples.

[0115] Comparative examples 1 to 3 show that two components are essential for carrying out the process of the invention: ethyne has to be contacted firstly with catalyst and secondly with ethene.