IL29769A

IL29769A - Production of carboxylic acids and esters

Info

Publication number: IL29769A
Application number: IL29769A
Authority: IL
Original assignee: Monsanto Co
Priority date: 1967-04-05
Filing date: 1968-04-05
Publication date: 1972-10-29
Also published as: IL29769A0; NL6804850A; BE713296A; GB1233121A; SE364255B; FR1573131A; DE1767151C3; NL149779B; DE1767151A1; GB1233122A; BR6898142D0; DE1767151B2; AT295487B

Description

PRODUCTION OP CARBOXYLIC ACIDS AND ESTERS This invention relates to a process for the transfor¬ mation of reactants selected from the group consisting of alkyl compounds having n carbon atoms, where n is a whole number from 1 to 20 carbon atoms, and aryl compounds having n carbon atoms, where n is a. whole number from 6 to 20, the said reactants being further selected from the group consisting of alcohols, halides, esters, and ethers,, to obtain a mixture comprises?, of the organic acid having n+1 carbons atoms, the ester of the alcohol having n carbon atoms with the said acid, and mixtures thereof, the said process comprising contacting the said reactant with carbon mon¬ oxide in the presence of a rhodium component, and a promoter sub¬ stance selected from the group consisting of bromine, iodine, and compounds of said halogens, and at a temperature of at least I . . . 50 °C.

The invention also relates to a new composition of matter, a catalyst comprising the combination of a rhodium com¬ ponent, and a promoter substance selected from the group con¬ sisting of bromine, iodine, and compounds of said halogens, and a process for making said catalyst.

This invention^relates to a process for the preparation..of carboxyllc acids and esters by . i the reaction of alcohols and carbon monoxide In the presence of catalyst compositions essentially comprisin rhodium compounds and complexes, to yield carboxyllc acids and esters selectively and efficiently.

Carbonylation processes for the preparation of carboxyllc acids from alcohols are well known in the art and use of a number of catalysts for the synthesis of carboxylic acids by reaction of alcohols with carbon monoxide at elevated temperatures and pressures in both gas phase fixed bed reactions and liquid phase reactions. Catalysts such as phosphoric acid, phosphates, activated carbon, heavy metal salts such as zinc and cuprous chlorides, silicates of. various metals, and boron trifluorlde in various hydration states have been reported to function for the production of acetic acid by reaction of methyl alcohol and carbon monoxide at elevated temperatures and pressures of the order of 00°C and 10,000 psig, respectively. However, even under such severe conditions the yields of acid were substantially poor, and, therefore, uneconomical. Somewhat less severe reaction conditions of temperature and/or pressure have been reported in the literature employing specific catalyst compositions, e.g., 3J>0°C-J>hO°C using liquid phosphoric acid containing copper phosphate ; 300°C- 500°C and 2000 psig-4000 psig using active charcoal Impregnated w¾th phosphoric acid; and 26o°C-560°C and 2800 pslg-15,000 psig using metal carbonyls, such as iron, cobalt and nickel, in conjunction with their halides or free halogens in the liquid phase. Even using these specific catalyst compositions at the , less severe reaction conditions, substantially poorer yields of the desired carboxylic acid product and substantially slower reaction rates are obtained than those achieved in the process of this invention.

Certain disadvantages present in the carbonylation processes described in the prior art are catalyst instability, lack of product selectivity, and low levels of catalyst reactivity. One particular disadvantage of carbonylation processes of the prior art is their dependence upon the use of and nickel carbonyl, all of which require the use of high partial pressures of carbon monoxide to remain stable under the necessarily high reaction temperatures employed. For example, dicobalt octacarbonyl requires partial pressures of carbon monoxide as high as 3000. psig to 10,000 pslg under normal carbonylatlon conditions of 175°C to 300°C.

Still another disadvantage of carbonylatlon processes disclosed in the prior art is their relatively low level of activity. This low level of activity requires higher catalyst concentrations, longer reaction times, and higher temperatures to obtain substantial reaction rates and conversions. Consequently larger and costlier processing equipment is required.

Another disadvantage of carbonylatlon processes disclosed heretofore is their Inability to maintain high selec- . j tivity to the desired carboxylic acid at temperatures required for high conversion, levels and high reaction rates. At these higher temperatures undesirable byproducts comprising substantial amounts of ethers, aldehydes, higher carboxylic acids, carbon dioxide, methane and water are formed, thereby resulting in substantial yield losses and necessitating additional product purification and recycle steps in the processing.

Another disadvantage of carbonylatlon processes described in the prior art is- heir dependence on catalyst systems which require the use of substantially chemically pure carbon monoxide feedstocks to maintain high selectivity and high yield to . the desired carboxylic acid product. For example, certain cobalt containing catalyst systems described heretofore when employed with carbon monoxide feed streams containing Impurities such as hydrogen, result in the production of a number i of undesirable b roducts includin methane arbon di x d carboxylic acid, and carboxylic acids of higher carbon number than desired. Consequently, substantial loss in selectivity, and yield to the desired carboxylic acid occurs. Catalysts of the prior art cause the formation of troublesome gaseous byproducts such as carbon dioxide and methane as well as dimethyl ether in the reactor system, thereby suppressing the carbon monoxide partial pressure and ultimately causing a decrease in the desired carbonylation reaction rate. Often additional processing steps are required to remove these undesirable byproducts, necessitating the use of larger and costlier processing equipment.

One embodiment of the present invention which uses a solid catalyst comprising the rhodium component overcomes the above difficulties by _ "providing" a system for continuous separation of products from the solid catalytic phase. These advantages are even more important when utilizing a catalyst comprised of an expensive metal compound, where utilization in industrial applications requires an absolute minimum of catalyst losses. .

Still another object of the present invention"is to provide a more selective and more reactive carbonylation catalyst composition for the production of carboxylic acids.

Another object of the present invention is to provide a carbonylation catalyst composition which results in the production of a higher yield of the "desired carboxylic acid with no substantial formation of ethers, aldehydes, higher carboxylic acids, carbon dioxide, methane, water and other undesirable byproducts. ! . ' ■ Still another .object of the present invention is the efficient and selective production of carboxylic acids or their esters by reaction of alcohols and alcohol derivatives with carbon monoxide in the presence of an improved and more stable catalyst, thus enabling the use of lower catalyst . concentration, lower temperature, lower pressure, and shorter contact time than has been generally possible heretofore and facilitating product isolation, catalyst recovery and recycle without substantial catalyst decomposition and loss.

Another object of the present invention is to provide novel heterogeneous catalysts comprising the combination of an inert carrier having dispersed thereon a rhodium component.

In accordance with the present 1 invention, alcohols having n carbon atoms are converted selectively to a mixture comprised of an acid having n + 1 carbon atoms and the ester of the said alcohol with the said acid, by reacting the alcohol or an alcohol derivative in the liquid phase with carbon monoxide at temperatures from about 50°C to 500°C and at partial pressures of carbon monoxide from 1 psig to 15,000 psig preferably 5· psig to 3,000 psig, and more preferably 10 psig to 1, 000 psig, although higher pressure may be employed, in the presence of a catalyst system comprised of an active portion, for example, a rhodium containin component, and a promoter portion, for example, a . or iodine. The present^process is particularly advantageous at lower pressures, although higher pressures may also be used.

In accordance with the present invention, alcohols having n carbon atoms (n is 1 to 20) are converted to a mixture comprised of an acid having n + 1 carbon atoms and the ester of the said alcohol with the said acid, by reacting the alcohol or an alcohol derivative in the vapor phase with carbon monoxide ' substrate which is employed in the present catalysts cons s s o a porous solid of such size that it can be employed in fixed or fluidized-bed reactors, e.g., from 400 mesh/inch to 1/2 -inch particle sizes. The range of variation of the pore volume rela- tlve to solid weight is from 0.05 to 2.5 cm /gram of the porous 3 phase, with a preferred range of from 0.05 to: 1.5 cm /gram.

The carrier materials are exemplified, but not limited by pumice, alumina, silica, silica-alumina, aged or deactivated silica-alumina cracking catalyst, magnesia, diatomaceous earth, bauxite, titania, zirconia, clays, both natural and acid treated such as the Super-Filtrols, attapulgus clay ( attapulgite) , lime, magnesium silicate, silicon carbide, activated and unactivated carbons, zeolites as well as the zeolitic molecular sieves, solid foams, such as ceramic honeycombs,- and porous organic polymers. The. above carriers are used as regular and Irregular particles and as capillary tubes, and interspacing elements such as shapes, extrudates, ceramic rods, balls, broken pieces, tiles, and the like disposed within the reactor.

As referred to above, for purposes of the present Invention, the catalyst as charged is a rhodium component which may be rhodium metal or a compound containing rhodium and other moieties if desired. The catalyst essentially includes a rhodium component, as the active component, such as rhodium metal, RhCl3, RhBr3, Rh2( CO) 4Ig, .Rh2( CO) 4CI2, Rh[( CeH5) 3P]2( CO) CI, and Rh[( C6H5)3P]2(C0)C1( CH3I) , etc.; however, the catalyst may be composed of two distinct components, namely the active catalyst portion, e.g., the aforesaid rhodium component, and a halide portion as the second component which may or may not be catalyti- alcohol, or by rendering the rhodium species less volatile tTran the unmodified rhodium carbonyl.

The active catalytic portion or first component is a rhodfrim species such as rhodium metal, simple rhodium salts, organorhodium compounds, and coordination compounds of rhodium, specific examples of which may be taken from the following partial list of suitable compounds: RhBr[(CeH5)3P]3 [( n-C4H9)4N] [R ( CO) 2 2 Jwhere X=Cl",Br~, I" RhI;[(C6H5)3P]3 [(n-C4H9)4As]2[Rh2(CO)2Y4]where Y=Br", I" RhCl[(C6H5)3P]3 [(n-C4H9)4P][Rh(CO)l4] RhCl[(C6H5)3P]3H2 RhCl3-3H20 Rhl(CO) [(CeH5)3Sb]£l [(CeH5)P]3Rh(CO)H RhBr3'5H20 RhCl3 · [Rh( C2H4)2C1]2 Rh2( CO) 4C12 RhBr3 K4Rh2Cl2(SnCl3)4 Rh2( CO) 4Br2 Rhl3 i " K4Rh2Br2(SnBr3)4 Rh2(CO)4I2 Rh metal K4Rh2I2(SnI3)4 Rh2(CO)8 Rh203 R [(CeH5)3P]2(C0)l Rh[(C6H5)3P]2(CO)Br Rh(.N03)3 Rh[(CeH5)3P]2(CO)Cl Rh[(n-C4H9)3P]2(CO)Br RhCl[(C6H5)3P]2(CH3l)2 Rh[(n-C4H9)3P]2(C0)I Rh(SnCl3) [(C6H5)3P]3 RhCl(CO) [(C6Hs)3As]2 However, the active catalytic portion or primary component of the catalyst system of this Invention is preferably a coordination compound of rhodium, carbon monoxide, and a halide such .as chloride, bromide and iodide, as well as suitable amine, organo-phosphlne, organo-arsine, and/or organo-stlblne ligands and, if desired, other ligands e.g., halide such as chloride, iodide and bromide and trihalostannate- such as the corresponding chloride, bromide or iodide, necessary, to satisfy the coordination number and oxjidation number of the central metal atom, rhodium, and thus form a coordination compound or complex of rhodium such as Rha(C0)4Br2, Rh[( phenyl) 3P]2( CO) CI, or [( phenyl) 3P]3RhI3, etc.

The term coordination compound or coordinatio comple used throughout this specification means a compound or complex formed by combination of one or more electronically rich molecules or atoms capable of independent existence with one or more electronically poor molecules or atoms, each of which may also be capable of independent existence. Suitable organo-nitrogen, organo-phosphorus, organo-arsenlc, and organo-antimony ligands which may comprise part of the rhodium coordination compound or other catalyst of this invention are those consisting of tertiary organo-nitrogen, organo-phosphorus, organo-arsenic, and organo-antimony compounds in which the nitrogen, arsenic, phosphorus, and antimony atoms are trivalent and are referred to in this specification as amines, phosphines, arslnes, and stibines, respectively. In the group of suitable ligands containing the trivalent nitrogen, An organic derivative of trivalent nitrogen, phosphorus, ara^iW, and antimony with the foregoing electronic configuration is, therefore, a suitable ligand for the rhodium containing catalyst of. this invention. Organic radicals of any. size and composition may be bonded to the nitrogen, phosphorus, arsenic, and antimony atoms, and the radicals are selected from the group consisting of alkyl and aryl groups. However, the preferred amine, phos-phine, arsine, and stiblne ligands are those consisting of at least one, but preferably one to three aryl-and/or aryloxy-groups as the organic moieties. For example, preferred ligands are illustrated by the following structural formula and examples: R3 where M=N, P, As, Sb, and R= phenyl( CeH5-) , phenoxy( CeH50-) , tolyl[CH3( CSH5) - ] n-butyl( n-C4H9- e.g. N(n-C4H9)3, P(CeHs)s, P(CQH50)3 As(C6H5)3, Sb(CeHs)3, P[CH3(CeHs) ]3 A preferred group of ligands associated with the rhodium and the organic phosphorus, arsenic, and antimony derivatives has alkyl radicals of 1 to lBcarbon atoms, aryl radicals having from 6 to 18 carbon atoms and halogen radicals selected from the group consisting of chlorine, bromine and iodine. A preferred catalyst is composed of a rhodium atom having as ligands, carbon monoxide, and at least one halogen ligand selected from the group consisting of chlorine, bromine and iodine, and at least two ligands selected from the group consisting of phosphorus, arsenic, and antimony derivatives having alkyl radicals of from 1 to 18 carbon atoms or aryl radicals having from 6 to 18 carbon atoms.

A particular advantage of the rhodium carbonyl phosphlne chloride compounds, such as Rh( CO) [P( CQH5) 3 ] ¾C1, when used as the first component of the catalyst system of this at high temperature even in a vacuum. Certain carbonylatlon ^ catalyst systems described in the prior art such as cobalt carbonyl often undergo substantial decomposition under conditions necessary for product isolation, catalyst recovery, and recycle processing and are therefore not suitable for the process of this ammonium, phosphonium, arsonium, stibonium halide, etc . , and ; may he the same or different from any halogen component already present in the active catalytic portion or first component of the catalyst system. Halogen or halide compounds are suitable for the promoter portion of the catalyst, but those containing iodine and bromine are preferred. Accordingly, suitable promoters comprising the second portion of the catalyst system of this invention may be selected from the following list of preferred halogen and/or halogen containing compounds: RX n where R =" any alkyl-, e. g. , CH3i, C6H5Br, ■ (n is 1 to 5) alkylene or · aryl-group CH3CH2I, ICH2CH2I, etc. and X : CI, Br, or I X2 or g where X = CI, .Br, or I, e. g. , Br2, I2, I3, etc. HX where X r CI, Br, or I, e. g. , HBr, HI Hp where R z any alkyl- or et g. > CHajJI, etc. 0 aryl-grou • 0 and X .= CI, Br, or I R4MX, R4MX3, or R3M 2. where R = Hydrogen or any e. g. , NH4I, PH4I3, alkyl-or aryl-group PH3I2/ PH3Br2, M - N, . P, 'As, or Sb (CsH5)3Pl2., and/or combina ions of X = CI, Br, or I R, ■ , and X The active catalyst or first component of the catalyst system of this invention may be preformed prior to charging the reactor, or it may be formed in situ on the carrier in the reactor. For example, it may consist of either rhodium metal, a simple rhodium salt, rhodium carbonyl, rhodium carbonyl salt, or rhodium in complex combination with carbon monoxide and suitable organo phosphlne, ,.arsine, or stibine ligands and also other ligands, e.g., halide as described above. Generally, any preformed rhodium compound may be charged to the reactor. If desired, the active catalytic rhodium component described above may be prepared from any of the simpler types of rhodium salts.

The halogen promoter portion or second component of the catalyst may be charged to the reactor separately from the active catalyst or first component, or it may be incorporated into the active component, e.g., Rhl3.. The active rhodium compound or first component of the catalyst system may be prepared prior to charging the reactor or generated in situ.

Subsequently, after the first component is in the reactor

Claims

P.A. 29769/2 Claims t

1. * A process for the trans ormation of reactants selected from the group co nisting of alkyl compounds having n carbon atoms, where n is a number from 1 to 20 carbon atoms , and aryl compounds having n carbon atoms, where n is a whole numbe from 6 to 20, the said roaslants being further selected fro the group consisting o alcohols, halidos, esters, and. thers, to obtain a mixture comprised o the organic acid having n*l carbon atoms, the este of the alcohol having n carbon atoms with the said acid, and mixtures thereof, the said process comprising contacting the said reactant with carbon monoxide in the presence of a rhodium component, and a promote substance selected from the group consisting of bromine, iodine, and compounds of said halogens, and at a temperature of at least 5Q°C*, and when the feedstock is an ester, ether or hali e derivative, carrying out the reaction in the presence of water. 2· A process according to claim 1, characterized by carrying out the reaction in the presence of a solution containing the rhodium component* 3. A process as claimed in claim 1 or 2 wherein the feedstock is an alcohol and the process is . effected in the presence of water* '4. A process as in claim 2 in which the said solution contains an inert solvent having a boiling point which is at least 25°C (S.T. P. ) higher than . the acids and esters.-1 5. A process as in claim 1 or 2 in which the partial pressure of carbon monoxide is from 1 psig to 15,000 psig... 6.. A process as in claim 1 or 2 in which the partial pressure of carbon monoxide is from 5 psig to 3,000 psig. 7. A process as in claim 1 or 2 in which the partial pressure of carbon monoxide is from 10 psig to 1,000 psig. . 8. A process according to claim 1 for the manufacture of at least one compound selected from the group consisting of acetic acid and methyl acetate, which comprises contacting a feedstock of at least one member of the group consisting of methanol, methyl acetate, dimethyl ether, and methyl iodide with carbon monoxide, in the presence of a solution containing a rhodium compound, and a promoter sub and compounds . of said halogen at a. temperature of, ,. from 59°C to 300°C,· the process being effected in the presence of vatfer. whe the eedstock is methyl acetate, dimethyl .ether or methyl iodide., . ;l r , 9· A process as in claim 8 In which the said feedstock is methanol* 10· process as claimed in claim 8 whe ein the process is effected i the presence of water ·. when the, feedstock is methanol. 11. A process as in claim 8 in which the said solution also co tains acetic acid. acetate, which comprises contacting a _.,..,.· . P*A. 2 769/2 vapor feedstook of at least ' one* m.e'.mber;of the groupv consisting of methanol, methyl acetate, dimethyl ether, and methyl iodide with carbo monoxide, in the presence of a supported catalyst comprising a rhodium component upon a carrier, the said process being conducted in the presence of a promoter substance selected from the group consisting of bromine, iodine, and compounds of said halogens at a temperature of from 50°C to 500°C, said process being effected in the presence of water when the feedstock is an ester, ether or halide derivative. 15» A process as in claim Ik in which the said feedstock is methanol* 16. A process as claimed i claim 14, wherein the process is effected in the presence of water when the feedstock is methanol* 17· A process as in claim l in which the said feedstock also contains methyl acetate* 18. A process according to any o claims 1 and 12-17, which comprises contacting the reactant in vapor form with carbon monoxide i the presence of a supported catalyst comprising the decomposition products of rhodium nitrate dispersed upon a carrier. 19. A process according to any of claims 1 and 12-16, which comprises contacting^ the vapor reactant feedstock in the presence of a supported catalyst essentially comprising rhodium oxide upon a carrier. 20. A. process as in any of claims 1 and 12-19 in which the. partial pressure of carbon monoxide is from 0.1 psia to 15,000 psia. 21. A process as in any of claims 1 and 12-19 in which the partial pressure of carbon monoxide is from 5. psia. to 3,000 psia. 2

2. A process as in any of claims 1 and 12-19 in which the partial pressure of carbon monoxide is from, 10 psia to 700 psia. 2

3. A process as in any of claims 1 and in which the precursor to the rhodium component is selected from the group consisting of rhodium compounds, rhodium complexes and rhodium metal. 2

4. A process as in any of claims 1 and 12-19 in ; 2

5. A process as in any of claims 12-19 in which the said carrier is carbon. 2

6. A process ,as in any of claims 1-25 in which the said promoter is selected from the group consisting of iodine and compounds thereof. 2

7. A process as in any of claims l-r25 in which the said promoter is an a'lkyl ' iodide in which the said alkyl radical has 1-20 carbon atoms. 2

8. . A process as in any of claims 1-27 for the production of a high . proportion of acid relative to ester, which comprises conducting the process with the ratio of alcohol to ester being from 0.001 to 2.0. 2

9. A process as in any of claims 1-27, for the production of a high proportion of ester relative to acid, which comprises conducting the process with the proportion of the alsohol relative to the ester being from 10 to 10,000. 30. A process as in any of claims 1-27 comprising conducting the process with the ratio of the alcohol to the 31. A process as in any of claims 1-30 in which the' carbon monoxide is supplied as a gas mixture containing from 1 vol. % carbon monoxide to 99.9 vol . % carbon monoxide, and with the remainder of said gas mixture being selected . from the group consisting of nitrogen, noblei gases , hydrogen, carbon dioxide, water and paraffihic hydrocarbons having from 1 to 4 carbon atoms. · 32. A process as in any of claims 1-22 in.which the. said rhodium component is a rhodium halide. .33. A process as in any of claims 1-22 in which the said rhodium component is a rhodium carbonyl halide. 34. A process as in any of claims .1-22 in which the said rhodium component is rhodium trichloride. 35. A process as in any of claims 1-22 in which the said rhodium component is an aryl phosphine complex of rhodium. 36. A process as in any of claims 1-22 in which the said rhodium component contains carbon monoxide and at least one halogen ligand selected from the group consisting of .chlorine, bromine', and iodine; and at least' two ligands selected from, the . group consisting of phosphorus, . arsenic, and antimony derivatives having aryl radicals from 6 to 18 carbon atoms . 37. A process according to claim 1 for the manu¬ facture of at least one compound selected' from the group con- I .' ■' . ' sisting of acetic acid and methyl acetate, which comprises contacting a feedstock of at least one member of the group con¬ sisting of methanol, methyl acetate, dimethyl ether', and methyl iodide with carbon monoxide, in the presence of a supported rhodium catalyst prepared by preparing a solution of a rhodium metal and rhodium compounds, contacting the rhodium in solution with a carbon monoxide component with a. halide component, the said halide component being selected from the group consisting of bromine, iodine, and compounds thereof, to provide a solu¬ tion of a rhodium complex, and thereafter impregnating the rhodium solution upon a carrier, and drying the resultant product; the said process . being conducted ' in. the presence of a promoter substance selected from the group consisting of bromine, iodine, ' ' ' ' ' ' ' ■' ' 38. A process according to claim 37 which com¬ prises contacting the feedstock in vapor form. . 39. .A process as in claim 37 in which the precurso to the rhodium component is rhodium dicarbonyl chloride dimer. 40. A process as in claim 37 in which the rhodium is supported on carbon. for carrying, out a process as claimed in 41. As a composition of matter, a ca.talyst/com- Claim 1 prising the combination of a rhodium component, and a promoter substance selected from the group consisting of. bromine, iodine, and compounds of said halogens. 42. As a composition of matter, a catalyst solution according to claim 41, comprising a solvent selected from the group consisting of an alcohol having n carbon atoms, where n is a whole number from 1 to 20, an acid having n + 1 carbon atoms, the ester of the said acid and the said alcohol, the diether of the said alcohol, a halide of the said alcohol, and mixtures thereof, the said solution containing a rhodium compound, as the active catalytic component, and . a promoter substance selected from the. group consisting of bromine, iodine, and compounds of said halogens . ■ ._. 43. As a composition of matter, a catalyst accord¬ ing to claim 41.comprising the supported rhodium catalyst 'produced by preparing a solution of a rhodium component, selected from the group consisting of rhodium metal and rhodium compounds, contacting the rhodium in solution with a carbon monoxide component and a halide component, the said halide component being selected from the group consisting of bromine, . iodine, and compounds thereof, to provide a solu- . tion of a rhodium complex, and thereafter impregnating the rhodium solution upon a carrier, and drying the resultant product. 44. A process for manufacturing a supported rhodium according to Claim 1 catalys^ which comprises preparing a solution of a rhodium component, selected from the group consisting of rhodium metal and rhodium compounds, contacting the. rhodium in solution with a . carbon monoxide component and a halide 'component, the said halide component being selected from the group consisting of romine, iodine, and compounds thereof, to provide' a .solutio of a rhodium complex, and thereafter impregnating the rhodium solution upon a carrier, and drying the resultant product. " / 45. A process according to claim 44 which comprises first preparing a.halide containg solution of the rhodium component, .then contacting the rhodium in .solution with the carbon monoxide component. . .. .. 46. A process according to claim 44 which comprises first preparing a carbonyl-ligand containing solution of the rhodium component, then contacting ..the rhodium in solution with the halide component. 47. The process of claim 44 in which .the final rhodium complex essentially includes as ligands, carbonyl and halide moieties. , 48. The process of claim 44 in which the rhodium in th final, rhodium complex . is at . least in part in a monovalent state.