[1]3 1 7 9 3 . @ 2 5 7 Ullited States Patent Office Patented Feb. 19, 1974 3,793,257 OLEFIN ISOMEERIZATION AND/OR HYDROGENAIION THROUGH RUTI]ENRJM HYDRIDE COMPLEX-CATALIZED PROCESSES FiHppo PenneIla and Mark R. Rycheck, BartlesviRe, 5 Okla., assignors to Phillips Petroleum Company No Drawing. FiIed Nov. 1, 1971, Ser. No. 194,698 Int. Cl. C07c 5100, 5114 11 . U.S. CL 260-683.2 23 C ams 10 ABSTRACT OF THE DISCLOSURE R uthenium hydride complexes containing tertiary phosp hine, arsine, or stibine ligands are employed. as catalysts fo r isomerization and/or hydrogenation of olefins. Ter1 5 m inally unsaturated olefins are selectively isomerizbd to in ternally unsaturated olefins by complexes that - c(:)ntain ni trogen or ammonia. T his invention relates to olefin double bond isomeriza2 0 ti on and/or olefin hydrogenation by contacting an olefin w ith a ruthenium hydride complex containing te@rtiary p hosphine, arsine, or stibine ligands. V arious processes for isomerizing and/or hydrogenating ol efins are known in the art. In general, prior art processes 2 5 s uffer from one or more limitations such as excessive olefi n cracking, undesirable olefin polymerization, - excessive r andomization, or unfavorable economics. The - transition m etals of Group VHI in elemental, compound and compl ex form, including such compounds as ruthenium chlor3 0 id e, ruthenium oxide, dichlorotris(triph enylphosphine) r uthenium (II), are known to have activity as catalysts fo r isome'rization and/or hydrogenation of olefins. The id entification of new catalyst systems which are eft@ective is omerization and/or hydrogenation catalysts, particularly 3 5 w here the catalyst systems can be applied selectively in a p redictable manner, is of continuing interest and of pote ntial economic benefit to the chemical industry at large. It is an object of this invention to provide a proce@ss for 4 0 th e double bond isomerization of olefins. In addition, it is a n object to catalytically isomerize terminal olefins into in ternal olefins. Another object is to provide a process for . th e isomerization of straight-chain terminal olefins to st raight-chain internal olefins wherein the internal olefin 4 5 m ixtures contain substantially more trans isomers than ci s isomers. In addition, it is an object to provide catalyst s ystems which catalyze the conversion of terminally uns aturated olefins to internally unsaturated olefins and inhi bit the conversion of internal olefins to terminall[y un5 0 s aturated olefins. Still another object is to provide a p rocess for the hydrogenation of olefins. Other objects, a spects and advantages of this invention will be apparent fr om the written description and the appended claims. A ccording to this invention, the double bond of an isom5 5 e rizable olefin reactant is shifted by contact with a r uthenium hydride complex containing tertiary - phosphine, a rsine or stibine ligands. In addition, an olefin is hydrog enated by contact with hydrogen and a ruthenuim hyd ride complex. 6 0 T he ruthenium hydride complex employed in this inventi on, can be represented by the formula (R3Q)3RuH2Z 65 wherein each Q is independently selected from phosphorus, arsenic, and antimony; Z is selected from H2, N2, or NH3; and wherein each R is independently selected from organic radicals containing up to 20 carbon atoms. Preferably the organic radical is free of active hydrogen 70 atoms and reactive unsaturation. Preferred R groups are alkyl, cycloalkyl and aryl hydrocarbyl radicals and mix2 tures thereof, such as alkaryl, aralkyl, alkcycloalkyl, with each R group containing up to 10 carbon atoms. Some examples of suitable ruthenium complexes are: (triphenylphosphine) 3RuH4 (triethylphosphine)3RuH2(N2) E (4-methylphenyl) 3phosphine]3RuH4 (phenyldim--thylphosphine)3RuH2(NH3) (diphenylmethylphosphine) 3RuH4 (dimethyllaurylarsine)3RuH2(N2) (trimethylarsine)3RuH4 (tribenzylarsine)3RuH2(NH3) (tricyclohexylarsine) 3RuH4 (trieicosylarsine) 3RuH2 (N2) (triphenylstibine) 3RUH4 E (4-methylcyclohexyl) 3phosphinel 3RuH4 (tridecylstibine) 3RuH2 (NH3) (triphenylphosphine)2(triphenylarsine)RuH4 (triisobutylstibine)3RuH2 (N2) (trioetylstibine) 3RuH2(NH3) (triphenylphosphine) 3RuH2 (N2) and admixtures thereof. The ruthenium hydride complexes of this invention can be prepared by any convenient method known in the art. Generally convenient methods are fflustrated in the Journal of the American Chemical Society (JACS) 90, 7172 (1968) and JACS 92, 3011 (1970). An example of a convenient method is the reaction of a suitable ruthenium compound with an alkali metal borohydride in the presence of an alcohol, such as the reaction resulting from an admixture of dichlorotris(triphen ylphosphine)ruthenium and sodium borohydride in methanol to yield tetrahydridotris ( triphenylphosphine) ruthenium. The ruthenium dinitrogen and ammonia complexes can be prepared conveniently by the addition of nitrogen or ammonia directly to a (R3Q)3RuH4 complex. A general procedure is provided by JACS 90, 7172 (1968) and JACS 92, 3001-3016 (1970). The ruthenium complexes employed in this invention are air-sensitive and are generally unstable in the presence of air or oxygen-containing atmospheres. Accordingly, the preparation and use thereof should exclude or appreciably restrict air or oxygen, as well as exclude aDy reactive substance or atmospheres which tend to reduce the effectiveness of the complex in an isomerization or hydro.-enation process. In general, the ruthenium complexes have limited solubility in commercially important olefin isomerization and hydrogenation process feedstocks. Advantageously, in some cases, therefore, the complex is employed in the presence of substantially inert solvents to facilitate mixing of olefin reactant and ruthenium catalyst. Representative mert organic solvents which can be used include aromatic hydrocarbons including benzene, toluene, ortho-xylene, meta-xylene, para-xylene, as well as other inert solvents including tetrahydrofuran and similar solvents. The ruthenium complexes can be employed in heterogeneous catalytic olefin isomerization and hydrogenation reactions by depositing the complex on a solid inorganic oxide catalyst support. Such support materials are commonly known as refractory oxides and include synthetic materials as well as acid treating clays or the crystalline aluminosilicates known in the art as molecular sieves. Synthetic refractory oxides are preferred. Exemplary synthetic refractory oxides include silica, alumina, silicaalumina, silica-magnesia, boria-alumina, sili ca-aluminiazirconia, and silica-titaniazirconia. Preferably, the support, prior to contact with the complex, is dried by calcining. Such a supported catalyst preferably contains from about I to about 10 wei.- ht percent ruthenium complex based on the weight of support.
[2]3 An advantage of this invention resides broadly in the effir,ient conversion of terminally unsaturated olefins to internaliy unsaturated olefins. This invention also finds particular utility with respect to the conversion of terminally unsaturated olefins to internally unsaturated olefins wherein significant quantities of trans olefin isomers are desired. 'nis trans olefin isomer utility is quite surprising and unexpected. Ordinarily, in niixtures of internally unsaturated isomers, such as isomers unsaturated at the second to third carbon atom position, substantial quantities of both cis and trans forms of olefin isomer are present, with the trans form being generally slightly predominant. In addition, it is generally considered that the mechanism of double bond isomerization transformation is such that the olefin is presumed to go through the cis isomer stage, thus resulting in substantial quantities of cis isomers being present at all times. The conversion of olefins (R3Q) 3RuH2 Z catalyst in accordance with this invention apparently does not follow this mechanism. Another feature of the invention is that the (R3Q)3RuH2(N2) and R3Q)3RUH2(NH3) complex compositions of this invention hihibit the conversion of internally unsaturated olefins to terminally unsaturated olefins, thus resulting in substantial improvement in yield of internally unsaturated olefins. Thus, the process for conversion of olefins according to this invention an be employed to prepare internally unsaturated olefins as well as to selectively prepare trans olefin isomers. Still another feature of this invejition is that the (R3Q)3RuH4 complex compositions promote the hydrogenation of olefin, whereas the (RsQ)3RuH2(N2) and (R3Q)3RuH2NH3 complex compositions iiihibit the hydrogenation of olefins. Accordingly the (R,3Q) 3RuHd complex compositions are preferably employed in isomerization and/or hydrogenation processes. Any isomerizable olefin can be employed in the practice of this invention including acyclic monoenes and acyclic polyenes embracing diennes, trienes, conjugated diolefiiis, nonconjugated diolefins, mixtures thereof, and the like. The olefins can contain cycloalkyl or aryl substituents or mixtures thereof. Because of their commercial importance, preferred olefins contain from 4 to 20 carbon atoms per molecule, and more preferably from 4 to 10 carbon atoms per molecule. Representative ole:fins are the following: 1-butene, I-pentene, 1-hexene, 3hexene, 1-decene, 5-methyl-l-hexene, 7- methyl-l-nonene, 5-ethyl-l- octene, 2-butene, 2-pentene, 4-methyl-2-hexene, 4-phenyllbutene, 5-cyclopentyl-l-pentene, 4-phenyl-2-butene, 5-isopropyl-2-heptene, 2-decene, 2,3,4-trimethyl-6dodecene, 1,3-tetradecadiene, 4-eicosene, 1-(3-butenyl)- 4ethylbenzene, 1-(3-pentenyl)-3-methylcycloheptane, 1,3octadiene, 1,4,7-decatrine, and the like, and mixtures thereof. Any hydrogenatable olefin can be employed in the practice of this invention including acyclic monoenes and acyclic polyenes including dienes, trienes, conjugated diolefins, niixtures thereof, and the like. Hydrogenation process catalysts find particular utifity with respect to the hydrogenation of olefins having from 2 to 20 carbon atoms per molecule, preferably from 2 to 10 carbon atoms per molecule. Representative hydrogenation olefin feedstocks include ethylene, propylene, hexenes, heptenes, octenes, cyclooctenes, cyclododecenes, cyclopentenes, dodecenes, tetradecenes, eicosenes, butadiene, pentadienes, hexadienes, heptadienes, cyclooctadienes, cyclododecatrienes, vinylcyclohexenes, cyclopentadienes, butynes, mixtures thereof, and the like. The amount of ruthenium hydr e complex employed in the isomerization or hydrogenation processes can vary widely. Preferably, an amount of complex is used which affords a reasonable amount of isomerization and/or hydrogenation within a reasonable reaction period of time. 3:793,257 4 In general, ruthenium hydride complex:olefin weight ratios of from about O.,001 to about 10 parts by weight of complex per 100 parts by weight of olefin are suitabe to the practice of this invention. Time will be about 0.5- 100 hrs: The isomerization or hydrogenation processes can be carried out as either a batch or as a continuous process using any conventional apparatus. Depending on the mode of reaction and other conditions such as reaction terri10 p@rature, complex:olefin contact time can vary from I -minute to 100 hours, at any convenient pressure, such as 0-2000 p.s.i.g. Suitable hydrogenation pressure conditions provide for the introduction of hydrogen into the reaction vessel in 15 an amount sufficient to maintain the pressure at which the process is effective. However, it is to be understood that the reaction conditions can provide for a portion of the op-erating pressure to be supplied by hydrogen with the balance being supplied by the use of the inert gas, 20 such as argon, thus providing the operating pressure. The isomerization or hydrogenation reaction temperatures can vary widely. In general, the reaction temperature should be such that the reactants and ruthenium complex composites are stable and do not decompose into 25 undesirable by-products or inactive complex composites. Thus, the isomerization or hydrogenation process is generally carried out at a temperature in the range of from about -20o C. to about 70' C. and preferably at a temperature in the range of about O' C. to about 50' C. 30 Ordinarily, the temperature should not exceed about 80' C., at which temperature decomposition of the complex can begin. The reaction products of this invention can be separated from the reaction mixtures by any method known 35 in the art. Suitable separation techniques include filtration, distillation, decantation, adsorption, and the like. Preferred ruthenium hydride complexes in the isomerization of terminally unsaturated olefins to internary unsaturated olefins, particularly to the trans form, are 40 (R3Q)3RuH2(N2) and (R3Q)3RuH2(NH3) COMPlexes since these nitrogencontaining complexes are unusuauy effective inhibiting the reverse isomerization of internally unsaturated olefins to terminal olefins. Since the nitrogencontaining complexes are stabilized by the presence of 4, excess nitrogen gas, these isomerization reactions are often carried out employing nitrogen as a nonoxidizing at-mosphere, preferably at a reaction pressure greater than atmospheric. However, it has also been found that purging of the reaction zone containing these ruthenium nitro50 geri cornplexes by an inert gas such as argon restores the activity of the catalyst for the double blond isomerization of internal olefins. The (R3Q)3RuH2(NH3) COMplexes are not affected by purging with nitrogen, argon and the like as in the case of the (R3Q).RuH2(N2) COM5 5 plexes. Accordingly, under some reaction conditions, ammonia may be preferred. The following examples are given to illustrate the protesses of this invention and are not intended to unduly limit the scope of the present invention in strict accord60 ance therewith. EXAMPLE I The complex (triphenylphosphine)3RuH4, a nearly white solid, was prepared by the reaction of (triphenyl65 phosphine)3RuCI2 with sodium borohydride in methanol in accordance with the following procedure: At room temperature and pressure, a 1.0 g. (1.04 mmole) quantity of (triphenylphosphine)3RuCI2 was dispersed in 25 ml. methanol. A 0.25 g. (6.6 mmole) pellet of NaBH4 was 70 added with vigorous stirring under a slow stream of hydrogen. After 30 minutes, the rriixture was fdtered and the precipitate was washed with methanol. The precipitate was again placed in 25 ml. methanol and another 0.25 g. NaBH4 pellet added. The mixture was again ffl75 tered, washed with methanol and dried in vacuo. Ile
[3]5 yield was 0.84 g. (91 percent). The product recovered was analyzed and found to, , contain . in weight percent. Found Calculated Carbon ---------------- 72.6 72@ 4 Hydrogen -------------- 5.6 5' 54 PhosphGras ---- : ------ 10. 5 10.4 Chlorine --------------- 0.0 0. 0 EXAMPLE II The complex (triphenylarsine)3RuH4 was prepared by dissolving at room temperature and pressure and under a helium atmosphere, 0.4 g. (approx. 1.3 mmole) triphenylarsine in 35 ml. methanol. A 1.0 g. quantity of (tripheny larsine)2RUC12-MeOH was slurried in this solution and one pellet of NABI-L was added. When effervescence w.as over, another pellet was added and the mixture was stirred for I hour. The mixture was filtered, washed with methanol and dried in a helium atmosphere. A I . 1 g. quantity of (triphenylarsine)3RuH4 was recovered. EXAMPLE III The (triphenylarsine)3RuH4 prepared in accordance with Example II was reacted with nitr6gen by subjecting approximately 0.2 g. of the product of Example II to a stream of nitrogen in a 50 ml. flask for 24 hours. The product was (triphenylarsine)3RuH2(N2), EXAMPLE IV A 15 ml. quantity of pentene-I (about 9.6 g.) was added to 0.1 gram (triphenylphosphine)3RUH4 iii a closed vessel under an inert helium atmosphere. Thi@ iiiixture was stirred at room temperature and pressure. Periodically 5 microliters of liquid was removed and analyzed by gas-liquid chromatography. The following results were obtained: TABLEI Percent Time Pentejic4 Trans-2peiitene Cis-2pentene 0 --- -------------- 100 0 1.0 10 mi -------------- 28.9 64.6 6.43 30 iiainutes --------------- 28.0 64.7 7.25 I hour -------------------- 22.8 71.0 6.20 2 hours ------------------- 21.3 72.0 6.70 5 hours ------------------ 18.8 73.6 7.6 21 hours ------------------ 12.0 79.4 8.6 20 days ------------------- 1.7 80.3 17. - 7 The above results show that the ruthenium hydride complex is an effective catalyst for isomerization of olefins since a 71 percent conversion of said olefin to the pentene-2 isomer was obtained in 10 minutes. Iri addition, the above results show that the complex selectivity isomerizes the pentene-I to the trans-2 pentene isomer. EY-AMPLE V Pentene-1 was isomerized in accordance witli the procedure set out in the preceding example, with the following exception: The reactor vessel containing the (triphenylphosphine) 3RuH-4 complex, prior to initial addition of the pentene-1, was flushed with nitrogen for 30 minutes in order to convert the complex to (triphenylphosphine) 3Ruh2(N2) - The mixture was stirred at room temperature and pressure. Periodically, 5 microliters of liquid were removed and analyzed by gas-liquid chromatograpby. The following results were obtained: TABLEII Perceiit Time Pentene-I Trans-2 peiitene Cis-2 p 10 minutes --------------- 28.1 66.0 5. 9 1 hour -------------------- 24.3 68.8 6.9 IS hours ------------------ 10.9 80.5 8.6 20 days ------------------- 1.71 81.6 16.4 8,793,257 6 These results show that the (triPhenYlPhOSPhine)3RuH2(N2) complex is also an effective catalyst for isomerizing pentene-1 and also favors the forination of trans-2-pentene product. EXAWLE VI Into a closed vessel equipped with a rubber seal was placed 0.1 g. (triphenylphosphine)3RuH4. The vessel was 10 flushed with anhydrous ammonia for 5 minutes, then left standing overnight at room tempemture. After 16 hours, the solid catalyst composite had turned a deep yellow having been converted to 15 (triphenylphosphine)3RuH2(NH3). Ten ml. (about 6.4 g.) of pentene-I were added and the nuxture was stirred at room temperature and pressure. The mixture was periodically sampled and analyzed. The 20 results are set out below: TABLE ni Percent Time Pentene-1 Trans-2 pentene Cis-2 pentene 25 0 --------------------- 100 ---- ------------------------------ 28 - inutes --------------- 97.3 2.3 0.36 m 3 hours ------------------- 90.3 S. 5 I 7 hours ------------------- 82.2 16.5 1:2 74 h urs I ---------------- 32.0 63.1 4.6 76 hoours ------------------ 31.8 63.0 4.9 99 hours ------------------ 16 0 77 0 6.6 30 120 hours ----------------- 10:5 82:2 6.7 - I At this point the sampie was cooled to dry lee-acetone temperature, and the vessel was flushed with argon for I hour. The reaction mixture was then warined and room temperature and operation was resumed. 35 The above results show that the (triphenylphosphine)3RuH2(NH3) complex is also an effective isomerization catalyst for converting terminal olefms to internal olefins, particularly to the trans form. In addition, 40 the above example shows that purging of the reaction mixture with argon. increases the reaction rate somewhat. EY-KMPLE VI[[ Pentene-2 was isomerized by contact with (triphenyl phosphine)3RuH4 in a manner similar to the preceding 45 examples. A 0.1 g. quantity of the complex was stirred with 20 ml. (about 13 g.) of pentene-2 at room temperature and pressure with periodic sampling and analysis of the mixture. The results are shown below: TABLE IV 50 Percent Time n-Pentane I-Pentene t-2-pentene c-2-pentene 0--------------- 0.28 0.06 75.6 2CI 10minutes----- 0.36 0.50 76.2 22.1 55 30minutes----- 0.36 1.27 75.5 22.7 1 hour ---------- 0.36 1.58 75.4 22.6 3 hours --------- 0.34 1.85 75.2 22.6 19 hours ------- 0.34 1.91 76.4 22.4 68 hours -------- 0.34 1.92 77.1 20.7 60 These results show that the (triphenylphosphine) 3Ruh,, complex catalyzes the reaction of internal olefins slower than for the reverse process. C5 EXAMPLE VIH Pentene-2 was isomerized in accordance with the procedure set out in Example VI.I with the following excep70 tion: The (triphenylphosphine)3RuH4, prior to the initial addition of the pentene-2 olefin, was flushed with nitrogen for I hour, left under a positive nitrogen pressure for 16 hours, and flushed again with nitrogen for 3 additional hours at room temperature to form the (tri75 phenylphosphine)3RUH2(N2) complex. Thereafter, pen-
[4]7 tene-2 was added, and the mixture was stirred and sampled periodically. The results were as follows: TABLE V Percent Time n-Pentane Pentene-I Trans-2 pentene Cis-2 pentene Feed ------- 0.28 0.06 75.5 24.1 10minutes-- 0.30 0.10 75.3 24.3 30 minute - 0.30 0.10 76.5 23.0 1'75hourss_: 0.25 0.13 76.0 23.5 19.67hours-- 0.26 0.21 75.1 24.4 42.33hours-- 0.35 0.42 76.6 22.6 .T'he reaction vessel was then flushed with argon for 10 minutes, with the sample at 00 C., plus an additional 5 minutes purge with argon while the sample returned to room temperature. Stirring at room temperature with periodic sampling was resumed. TABLE V.-Continued Time Percent after flush n-Pentane Pentene-1 Trans-2 pentene Cis-2 peiitene 15n-inute,s-- 0.29 0.38 75.0 24.3 50 rainutes.. 0.28 0.60 76.3 22.5 6 hours ------ 0.33 1.42 76.4 21.8 22 hours ---- 0.29 1.86 75.8 22.0 - - From the above data, it is apparent that the (triph enylphosphine)3RuH2(N2) complex does not appreciably catalyze the isomerization of pentene-2 to pentene-I but this activity is significantly restored by flushing of the catalyst with argon. EXAMPLE DC This experiment was performed in accordance with the procedure set out in Example VII with the following exception-. The (tri phenylphosphine)3RuH4 complex was flushed with anhydrous ammonia, left under ammonia for 20 hours, and flushed again with ammonia at room temperature to form the (triphenylphosphine)3RuH2(NH3) complex before adding the pentene-2. The results were as follows: TABLE VI Percent Time n-Pentane Pentene-I Trans-2pentene Cis-2pentene 0------------ 0.28 0.06 75.6 24.1 4.5hours---- 0.28 0.06 75.6 24.1 At this time, the sample was Ruished with argon for 40 minutes, with the sample at O' C. untu no odor of ammonia could be detected in the flush gases. Stirring at room temperature and periodic sampling was resumed. TABLE VI.-Continued Time Percent after flush u-Peritane Pentene-1 Trans-2 pentene Cis-2 pentene 2.5hours---- 0.28 0.04 78.9 20. 8 66 hours---- 0.26 0.20 75.6 23.9 The above results indicate that pretreatment of the (triphenylphosphine)3RuH4 complex with ammonia substantiafly destroys the activity for isomerization of pentene-2 to pentene-1. Moreover, flushing with argon has little effect. Comparison of the data of this example -with those of Example VI indicates that the ammonia complex is selective for isomerization of terminal olefins to intemal olefins EXAMPLE X In to a 3-ounce reaction tube under helium was placed 0.1 g. of (triphenylphosphine)3RuH4 and 20 ml. (about 13 g.) pentene-2 isomer (same composition as in Example VII). The tube was placed in a bath at 15' C. and hydrogen added on demand with stirring at 40 p.s.i.g. for 20 minutes, thereafter at 60 p.s.i.g. Hydrogen consumption 3)793)257 8 was rapid for the first 15 minutes and hydrogen addition to the olefin was essentially complete after 2 hours. The reactants were left under hydrogenpositive pressure for 24 hours at room temperature. During this period, very little hydrogen was consumed. No hydrogen consumption occured during the -next six days. The liquid was analyzed and found to be pentane illustrating that the complexes of this invention are active for catalyzing hydrogenation of olefinic unsaturation. Reasonable variations and modifications are possible 10 within the scope of the foregoing disclosure and the appended claims to the invention. We
