GB2336154A - Process for Carbonylation of an Alcohol and/or Reactive Derivative thereof - Google Patents

Abstract

A process is for the liquid phase carbonylation of an alcohol or its reactive derivative to a carboxylic acid in the presence of a halide promoter and a Group VIII nobel metal catalyst is improved by the use of an asymmetric bidentate ligand having the formula:- wherein X and Y are independently either N, P, As, Sb, or Bi; R<SP>1</SP>, R<SP>2</SP>, R<SP>5</SP> and R<SP>6</SP> are independently selected from alkyl, substituted alkyl, phenyl, substituted phenyl and the group of formula: (W)(R<SP>3</SP>) a (R<SP>4</SP>) b (II) wherein W is independently O, N or S of valency m, R<SP>3</SP> is alkyl, substituted alkyl, phenyl or substituted phenyl, R<SP>4</SP> is either hydrogen or R<SP>3</SP>, a is a positive integer, and a+ b = m; and Z is a divalent linking group, provided that R<SP>1</SP>R<SP>2</SP> is not identical to R<SP>5</SP>R<SP>6</SP>.

Description

2336154 1 PROCESS FOR CARBONYLATION OF AN ALCOHOL AND/OR REACTIVE

DERIVATIVE THEREOF The present invention relates in general to a process for the liquid phase carbonylation of an alcohol and/or a reactive derivative thereof to produce a carboxylic acid. In particular the present invention relates to the liquid phase carbonylation of an alcohol and/or a reactive derivative thereof in the presence of a halide promoter and a catalyst system comprising a Group VIII noble metal component and a bidentate ligand.

The production of carboxylic acids by the carbonylation of alcohols in the presence of a catalyst system consisting essentially of a rhodium metal atom, a phosphorus-containing ligand and a halogen-containing compound as promoter is known from, for example, US Patent No. 4,670,570.

Our co-pending European Application Publication No.0632006 discloses a process for the liquid phase carbonylation of methanol or a reactive derivative thereof which process comprises contacting carbon monoxide with a liquid reaction composition comprising methanol or a reactive derivative thereof, a halogen promoter and a rhodium catalyst system comprising a rhodium component and a bidentate pho sphoru s- sulphur ligand, the ligand comprising a phosphorus dative centre linked to a sulphur dative or anionic centre by a substantially unreactive backbone structure comprising two connecting carbon atoms or a connecting carbon and a connecting phosphorus atom.

There is a need for improved ligand-containing carbonylation catalysts in carbonylation processes by way of improved stability and/or improved reactivity and/or other improvement, for example availability and/or cost.

Accordingly, the present invention provides a process for the production of a carboxylic acid by the carbonylation of an alcohol and/or a reactive derivative thereof, which process comprises reacting in the liquid phase carbon monoxide 1 --. 11 2 with a reaction composition comprising at least one alcohol and/or a reactive derivative thereof, a finite concentration of water, a halide co- catalyst and a catalyst system comprising a Group VIII noble metal and a bidentate ligand having the formula:- R' R 2 X- (Z) - (1) wherein X and Y are independently either N, P, As, Sb, or B1; W, R 2, R'and R 6 are independently selected from alkyl, substituted al phenyl, substituted phenyl and the group of formula: (W)(R 3).(R 4)b wherein W is independently 0, N or S of valency m, R 3 is alkyl, substituted alkyl, phenyl or substituted phenyl, R4 3 is either hydrogen or R a is a positive integer, and a + b = m; and Z is a divalent linking group, provided that R1R 2 is not identical to R'R'.

(11) In the formula (1) the divalent linking group may be a divalent linear or yl, branched group comprising carbon, nitrogen, phosphorus, sulphur or oxygen atoms. Such groups include polymeric chains comprising the aforesaid atoms in 25 the backbone repeat unit thereof Preferred bidentate ligands have the formula:- W' Rs' X'- (CR YR 4' Y R 2' R 6' wherein X' and Y' are independently either nitrogen, phosphorus, arsenic, antimony or bismuth, at least one of R 3 'and R 4' is (are) independently either hydrogen or 35 hydrocarbyl, 2 3 R", R 2 ', R" and R 6 are independently selected from alkyl, substituted alkyl, phenyl and substituted phenyl, at least one of which is substituted by one or more electron withdrawing groups provided that W' R 2' is not identical to Rs' R 6' n is an integer.

As regards the catalyst system the Group VIII noble metal is suitably rhodium.

In the bidentate ligand of the formula (I): - X and Y are preferably either nitrogen or phosphorus, more preferably phosphorus; when at least one of R3'and R 4' is hydrocarbyl it is suitably alkyl, preferably Cl to C4alkyl, for example methyl. Preferably no more than one of R 3 and R 4 is hydrocarbyl, more preferably both R3'and R 4 ' are hydrogen. Preferably n is an integer greater than 1, for example 2. Suitably (CR"R 4),' i S (CH2)2; Suitable electron withdrawing groups include halo substituents, i.e. fluoro, chloro, bromo or iodo, of which fluoro is preferred, and groups having the formula:- c / R8 \ k9 (m) wherein at least one of R 7 R9 is halo and the remainder, if any, is hydrogen.

Preferably R 7, R8 and R9 are all halo substituents which are suitably fluoro or chloro, preferably fluoro. As regards the phenyl group or groups substituted by one or more electron withdrawing groups the group(s) may be ortho-, meta- or para-substituted, or may be substituted in all the ring positions. Of these alternatives meta- or para- substitution is preferred, mono-, or di- meta substitution being most preferred. Ortho-substitution is least desirable. Whereas fully substituted phenyl groups may give highly active catalyst systems they tend to be unstable; the phenyl groups, whether or not substituted by one or more electron withdrawing groups, may be substituted by one or more electron donating groups, for example -0-alkyl groups, for example -OMe.

Suitable bidentate ligands include:

(i) (3 - F - C61-14)2P(CH2)2PM2 3 4 (ii) (3,5 - F2 - C6H3)2P(CH2)21? M2 (iii) (3,4,5 - F3 - C6112)2P(CH2)21? Ph2 (iv) (3 -CF3 - C6F14)2P(CH2)2P Ph2 (v) (3,5 - CF3 - C6H5)2P(CH2)21? M2 (Vi) (2,4,6 - F3 -C61A2)2P(CH2)21? Ph2 Of these (i), (ii), (iii) and (1v) are preferred.

The catalyst system may suitably include a metal promoter component. Suitable metal promoters include ruthenium, osmium, cadmium, mercury, zinc, gallium, indium and tungsten, typically ruthenium and cadmium. Suitable combinations of bidentate ligand and metal promoter include, for example:- (3 - F - C6F14)2P(CH2)2PM2/Ru, and (3 - F - C6H4)2P(CH2)2PM2/Cd. The metal promoter component may be added in any form which is either soluble in the reaction composition or is convertible under the reaction conditions into a soluble form. Examples of suitable ruthenium-containing compounds which may be used include ruthenium (111) chloride, ruthenium (M) chloride trihydrate, ruthenium (IV) chloride, ruthenium (111) bromide, ruthenium (M) iodide, ruthenium metal, ruthenium oxides, ruthenium (Ill) formate, [Ru(C0)3131-H', tetra(aceto)chlororuthenium (I1J11), ruthenium (M) acetate, ruthenium (M) propionate, ruthenium (III) butyrate, ruthenium pentacarbonyl, trirutheniumdodecacarbonyl and mixed ruthenium halocarbonyls such as dichlorotricarbonylruthenium (II) dimer, dibromotricarbonylruthenium (I1) dimer, and other organoruthenium complexes such as tetrachlorobis(4- cymene)diruthenium (II), tetrachl o rob ni s(benzene) dir-utheni urn (I1), dichlor(cycloocta-1,5-diene)ruthenium (11) polymer and tris(acetylacetonate)ruthenium (M).

Examples of suitable osmium containing compounds which may be used include osmium (111) chloride hydrate and anhydrous, osmium metal, osmium tetraoxide, triosmium dodecacarbonyl, pentachloro-u-nitrododiosmium and mixed osmium halocarbonyls such as tricarbonyldichloroosmium (11) dimer and other organoosmium complexes.

Examples of suitable cadmium-containing compounds which may be used include Cd(OAC)2, Cd12, CdBr2, CdC 12, Cd(OH)2, and cadmium acetylacetonate.

Examples of suitable mercury- containing compounds which may be used 4 the formula:- include Hg(OAc)2, H912, HgBr2, HgC 12, H9212, and H92C 12.

Examples of suitable zinc-containing compounds which may be used include Zn(OAC)2, Zn(OH)2, Zn12, ZnBr2, ZnC 12, and zinc acetylacetonate.

Examples of suitable gallium-containing compounds which may be used include gallium acetylacetonate, gallium acetate, GaC13, GaBr3, Gah, Ga2C14 and GafflH)3.

Examples of suitable indium-containing compounds which may be used include indium acetylacetonate, indium acetate, InC13, InBr3, InI and In(OH)3.

Examples of suitable tungsten-containing compounds which may be used include W(C0)6, WC14, WC16, VY'Brs, W12, C9H12W(M3 and any tungsten chloro. bromo-, or iodo-carbonyl compound. The molar ratio of each promoter to Group VIII noble metal catalyst is suitably in the range (0. 1 to 20). 1, preferably (0. 5 to 1 o): 1.

The Group VIII noble metal component and bidentate ligand having the formula (I) may be added to the liquid reaction composition in the form of a metal complex in which the bidentate ligand is coordinated to the metal. This is preferred when another transition metal capable of binding the phosphine is employed. For this purpose a Group VIII noble metal moiety having displaceable groups is premixed with the bidentate ligand in a suitable inert solvent, for example methanol, prior to addition to the liquid reaction composition. Taking rhodium as exemplary of the Group VIII noble metal, suitable rhodium moieties include for example [Rh(C02)C1]2, [Rh(C0)21]2, rhodium (H1) chloride trihydrate, rhodium (III) bromide, rhodium (M) iodide, rhodium (III) acetate, rhodium dicarbonylacetylacetonate, RhO(M3)3 and RhO(C0)(M3)2. Alternatively the Group VIII noble metal complex, may be formed in situ, by addition to the liquid reaction composition of, for example, the aforesaid rhodium moiety and the bidentate ligand having the formula (I).

The preferred catalyst system is believed to comprise the complex having 6 1 C0 m W' (CR"R4),, Rs' Y / 'I R 6' (IV) wherein M is a Group VIII noble metal, and R",R 2' R 3 ',R 4' R5',R6', X., Y' and n are as defined in the formula (1 The Group VIII noble metal of the catalyst system may suitably be present in the liquid reaction composition at a concentration of from 25 to 500Oppm metal and the mole ratio of the Group VIII noble metal to the bidentate ligand having the formula (I), preferably (1 may suitably be in the range from 1 to 10, preferably in the range from 1 to 2.

The halide co-catalyst may suitably be added in the form of a hydrogen halide or a hydrocarbyl halide, preferably the latter. Suitably the hydrocarbyl group is an alkyl group, preferably a lower, e.g. Cl to C4, alkyl group. Of the halides the iodide is preferred. A preferred halide co-catalyst is methyl iodide. The concentration of halide co-catalyst in the liquid reaction composition is suitably in the range of from 1 to 30% by weight, for example from 5 to 20% by weight.

A suitable alcohol reactant is any alcohol having from 1 to 20 carbon atoms and at least one hydroxyl group. Preferably the alcohol is a monofunctional aliphatic alcohol having from 1 to 8 carbon atoms. Most preferably the alcohol is methanol, ethanol and/or propanol. A mixture comprising more than one alcohol may be used. The carbonylation product of the alcohol will be a carboxylic acid having one carbon atom more than the alcohol and/or an ester of the alcohol and the carboxylic acid product. A particularly preferred reactant is methanol, the carbonylation product of which is acetic acid and/or methyl acetate.

Alternatively, or in addition, the reactant may be a reactive derivate of an alcohol. Suitable such reactive derivatives include esters, halides and ethers.

A suitable ester carbonylatable reactant is any ester of an alcohol and a carboxylic acid. Preferably the ester reactant is an ester of a carboxylic acid and an alcohol which alcohol has from 1 to 20 carbon atoms. More preferably the ester 6 7 reactant is an ester of a carboxylic acid and a monofunctional aliphatic alcohol which alcohol has from 1 to 8 carbon atoms. Most preferably the ester reactant is an ester of a carboxylic acid and methanol, ethanol or propanol. Preferably the ester reactant is an ester of an alcohol and the carboxylic acid product. Preferably the ester reactant has up to 20 carbon atoms. A mixture of ester reactants may be used. The carboxylic acid carbonylation product of the ester reactant will be a carboxylic acid having one carbon atom more than the alcohol component of the ester reactant. A particularly preferred ester reactant is methyl acetate, the carbonylation product of which is acetic acid.

A suitable halide carbonylatable reactant is any hydrocarbyl halide having up to 20 carbon atoms. Preferably the halide reactant is an iodide or a bromide. More preferably the halide component of the hydrocarbyl halide reactant is the same halide as that of the halide carbonylation promoter. Most preferably the hydrocarbyl halide is a hydrocarbyl iodide, most preferably methyl iodide, ethyl iodide or propyl iodide. A mixture of hydrocarbyl halide reactants may be used. The carboxylic acid product of the hydrocarbyl halide reactant will be a carboxylic acid having one more carbon atom than the hydrocarbyl halide reactant. The ester carbonylation product of the hydrocarbyl halide will be the ester of the hydrocarbyl halide and a carboxylic acid having one more carbon atom than the hydrocarbyl halide. A suitable ether carbonylatable reactant is any hydrocarbyl ether having up to 20 carbon atoms. Preferably the ether reactant is a dialkyl ether, most preferably dimethyl ether, diethyl ether or dipropyl ether. A mixture of ethers may be used. The carbonylation products of the ether reactant will be carboxylic acids having one carbon atom more than each of the hydrocarbyl groups of the ether and/or ester derivatives thereof. A particularly preferred ether carbonylation reactant is dimethyl ether, the carboxylic acid product of which is acetic acid.

A mixture of alcohol, ester, halide and ether carbonylatable reactants may be used in the carbonylation process. More than one alcohol, ester, halide and/or ether may be used. A particularly preferred carbonylatable reactant is methanol and/or methyl acetate, the carboxylic acid carbonylation products of which are acetic acid.

The reaction composition further comprises a finite concentration of water. Suitably water may be present at a concentration in the range from 0. 1 to 30%, for example from 0. 1 to 15%, by weight based on the total weight of the liquid reaction composition. Water may be formed in situ in the carbonylation reaction, 7 8 for example, by the esterification reaction between alcohol reactant and carboxylic acid product. The water may be introduced to the carbonylation reactor together with or separately from the other reactants such as esters, for example methyl acetate. Water may be separated from the reaction composition withdrawn from the reactor and recycled in controlled amounts to maintain the required concentration in the reaction composition.

Acetic acid may be present as a solvent in the reaction composition of the present invention.

The carbon monoxide reactant may be essentially pure or may contain inert impurities such as carbon dioxide, methane, nitrogen, noble gases, water and C, to C4 paraffinic hydrocarbons. The partial pressure of carbon monoxide in the carbonylation reaction may suitably be in the range from 1 to 70 barg.

The reaction may be carried out at a total pressure in the range from 10 to 100 barg. The temperature may suitably be in the range from 50 to 250'C, typically fi-om 100 to 2500C.

The process may be operated batchwise or continuously, preferably continuously.

An advantage of the process of the present invention is that the reactivity of a rhodium catalyst can be increased. In turn this allows the amount of halide co- catalyst employed in the process to be reduced, thereby reducing the amount of separation and recycle required.

Many of the bidentate ligands having the formula (1) are believed to be novel.

Accordingly in another aspect the present invention provides a bidentate 1 ligand having the formula (1) wherein either W'R 2' or Rs'R 6' is a group of the formula (V). - D E C (V) B X A) 2 wherein A, B, C, D, and E are independently selected from halogen or groups 35 having the formula (111) as hereinbefore defined other than the compounds:- 8 9 (3-F-C61-4)2P(CH2)2PPh2, (C6F5)2P(CH2)2PPh2, and is (3-CF3-C6H4)2P(CH2)2PPh2.

Examples of novel bidentate ligands having the formula (1 wherein either W'R2' or R"R6' is a group of the formula (V) include: (3,5-F2C6H3)2P(CH2)2PPh2; (3,4,5-F3-C6H2)2P(CH2)2PPh2; (2,4,6-F3-C6H2)2P(CH2)2PPh2and (3,5-CF3-C6H3)2P(CH2)2PPh2 In another aspect of the present invention there is provided a catalyst system comprising a Group VIII noble metal and a bidentate ligand having the formula (1), preferably (1 Preferably the Group VIII noble metal is rhodium.

The invention will now be illustrated by reference to the following Examples. In the Examples the following Experimental Method was used:Experimental Method A 300 m] Hastelloy B2 autoclave equipped with a dispersimax stirrer, ballast vessel and liquid catalyst injection system was used for a series of batch carbonylation experiments. At the end of the experiment liquid by-products and vent gases were analysed by gas chromatography (GC). For each batch carbonylation experiment the Rh complex [Rh(C0)2C1212 was dissolved in MeOH in the base of the autoclave and the phosphine under test was added with vigorous stirring. The autoclave was then sealed and flushed three times with carbon monoxide. Following this, the main liquid charge (water (H20), and acetic acid) was added to the autoclave via a charging vessel. The autoclave was then pressurised with carbon monoxide to a pressure of ca. 10 barg and heated with stirring (1500 r. p. m.) to 185T. Once stable at this temperature a small amount of carbon monoxide was fed forward from the ballast vessel to give an autoclave pressure of ca. 22 barg. The Mel charge (mixed with 2 g of AcOH) was 9 injected into the autoclave using an overpressure of carbon monoxide. After injection of the Mel, the autoclave pressure was kept constant at ca. 28 ( 0.5) barg using carbon monoxide fed from the ballast vessel. After 2 hr., a second aliquot of MeOH (9.36 g) was injected into the autoclave using the catalyst injection facility. The overpressure used for this injection was such that a pressure of ca. 49 barg was attained. After injection of the MeOH the autoclave pressure was kept constant using carbon monoxide fed from the ballast vessel. After a further 1 hr. the reaction mixture was cooled, the autoclave was vented and the vent gases sampled and analysed. The liquid reaction mixture was discharged from the autoclave, sampled and was analysed for liquid products and by-products. Component charges for Examples 1 to 10 and Comparison Tests (CTs) 1 to 5 are given in Table 1, and reaction rates at appropriate %wt levels of MeOAc in Table 2 Liquid and gaseous by-product yields are collated in Table 3. The aforesaid procedure is designed with a view to helping test which of the ligands remain co-ordinated to the metal. As an additional test to determine this p3 'NMR was employed.

2 CTI and CT2 are not examples according to the invention because none of W, R 6 2 6 R' and R contains an electron withdrawing group and R1R = R5R.

c CT3 is not an example according to the invention because none of R', R 2 ' R' and R 6 contain an electron withdrawing group.

2 6 CT4 is not an example according to the invention because WR = WR. CT5 is not an example according to the invention because WR' = WR 6. The rate of total gas uptake from the ballast vessel was monitored every 12 seconds using datalogging facilities. This data was subsequently used to calculate the rate of total gas uptake in mol/(1. hr.). at various methyl acetate concentrations.

A comparision of Example 5 with CT4 shows the advantage of having WR 2 different from R 5 R 6 in that although in both cases there are four fluoros on metapositions in the phenyl groups, which should result in substantially equivalent 2 6 electron withdrawing power, the compound in which WR is not identical to WR i.e. the compound of Example 5, is very much more active than the compound in which R1R 2 is identical to WR6, i.e. the compound of CT4.

Table 1. Charges for Bisphosphine Experiments Example Catalyst System [Rh(C0)202 Ligand MeOH H20 Mel AcOH MeOH 12 (g) (g) (g) (g) (g) (second (g) injection) (g) CTI Ph2P(CH2)2M2 0.241 0.982 12.28 18.75 22,52 96.71 9.36 CT2 Ph2P(CH2)21PM2 0.240 0.983 12.30 18.74 22.53 96.52 9.36 CT3 Ph2P(CH2)2AsM2 0.240 1.092 12.30 18.84 22.46 96.54 9.36 1 (3-F-C6H4)2P(CH2)2PPh2 0.241 1.074 12.25 18.77 22.48 98.58 9.36 2 (3-F-C6H4)2P(CH2)2PPh2 0.240 0.642 12.24 18.77 22.56 96.56 9.36 3 (3-F-C6H4)2P(CH2)2PPh2/RU3 0.240 0.643 12.28 18.75 22.69 97.33 9.36 4 (3-F-C6H4)2P(CH2)2PPh2/Cd 1 2 2 10.67 16.58 21.62 84.73 9.36 CT4 (3-F-C6H4)2P(CH2)2P(3-F-C6H4)2 0.240 1.160 12.25 18.83 22.52 96.52 9. 36 (3, 5-F2-C6H3)2P(CH2)2PPh2 0.240 0.758 12.34 18.79 22.88 97.30 9.36 11 12 6 (3,4,5-F3-C6H2)2P(CH2)2PPh2 0.240 0.756 12,36 18.79 22.89 97.32 9.36 7 (C6F5)2P(CH2)2PPh2 0.241 1.400 12.26 18,87 22.54 96.56 9.36 CT5 (4-CF3-C6H4)2P(CH2)2P(4-CF3- 0.241 1.654 12.28 19.20 22.69 97.38 9.36 C6H4)2 8 (3 -CF3 -C6114)2P(CH2)2PP112 0.240 0.791 12.37 18.80 22,74 97.46 9.36 9 (3,5-CF3-C6H3)2PCH2CH2PP112 0.240 1.010 12.36 19.02 22.56 96.51 9.36 (2,4,6-F3-C6H2)2PCH2CH2PP112 0.159 0.500 8.10 12.23 15.00 64.41 9.36 Notes 1) 1.463 g Cd(OAC)22H20 added 2) 1.038 g preformed ((3-FC6H4)2P(CH2)2PPh2)Rh(C0)13 added 3) 0.577 g Ru(C0)412 added CT denotes Comparison Test 12 13 Table 2 Rate Date for Bisphosphine Reactions Example Catalyst System Injection Rate at Rate at Rate at Injection Rate at Rate at 1 t=0 hr 15% 10% 5% 2 t=2 hr 10% 5% MeOAc MeOAc MeOAc MeOAc MeOAc (mol/1/hr) (mol/1/hr) (mol/1/hr) (mol/1/hr) (mol/1/hr) CTI Ph2P(C142)21Ph2 1.7 1.9 1.6 3.5 1.4 CT2 Ph2P(C142)2PM2 2.4 2.1 1.4 3.2 1.8 CT3 Ph2P(CH2)2AsM2 2.7 2.7 2.3 4.5 2.3 1 (3-F-C6H4)2P(CH2)2PPh2 7.0 6.2 4.6 6.4 5.4 2 (3 -F-C6H4)2P(CH2)2PPh2 6.2 5.0 3.5 6.9 4.3 3 (3-F-C6H4)2P(CH2)2PPh21Ru 20.4 13.7 6.4 21.0 11.9 4 (3-F-C6H4)2P(CH2)2PPh2/Cd 9.2 7.0 4.7 9.6 6.3 CT4 (3-F-C6H4)2P(CH2)2P(3-F-C6H4)2 2.0 2.0 1.8 3.5 2.5 (3,5-F2-C6H3)2P(CH2)2PPh2 8.9 8.5 6.2 9.8 8.2 13 14 6 (3,4,5-F3-C6H2)2P(CH2)2PPh2 9,3 7.6 5.7 6.8 7 (C6F5)2P(CH2)2PPh2 21.9 18.9 16.3 15.6 15.9 CT5 (4-CF3-C6F14)2P(CH2)2P(4-CF3- 2.6 2.3 1.8 2.2 2.0 C6H4)2 8 (3 -CF3 -C6H4)2P(CH2)2 PP112 6.3 5.6 4.4 6.6 5.2 9 (3,5-CF3-C6H3)2PCH2CH2PPh2 3.4 2.9 2.1 4.0 2.5 (2,4,6-F3-C6H2)2PCH2CH2PPh2 11.0 9,8 7,1 12.5 9.6 14 Table 3 BY-Product Data for Bisphosphine Reactions Example Catalyst System H2 C02 CH4 Acetaldehyde Ethyl Ethyl Propionic (%vol./vol.) (%vol./vol.) (%vol./vol.) (Ppm) Iodide Acetate Acid (Ppm) (Ppm) (Ppm) CTI Ph2P(C1-12)2PM2 5.2 1.9 0.5 204 29 6 4 CT2 Ph2P(CH2)2M2 4.9 1.6 0.4 133 18 5 CT3 Ph2P(CH2)2AsPh2 6.0 2.3 0.4 158 90 7 1 (3-F-C6H4)2P(CH2)2PPh2 19.9 7,2 0.3 46 497 24 2 (3-F-C6H4)2P(CH2)2PPh2 18.9 6.9 2.1 69 555 10 3 (3-F-C6H4)2P(CH2)2PPh21Ru 37.9 15.5 1.7 33 3051 35 4 (3-F-C6H4)2P(CH2)2PPh2/Cd 18.6 7.7 0.7 416 583 15 CT4 (3-F-C6H4)2P(CH2)2P(3-F- - - - 199 232 34 C61-14)2 (3,5-F2-C6H3)2P(CH2)2PPh2 30.7 12.7 0.4 156 1070 13 188 13 79 16 6 (3,4,5-F3-C6H2)2P(CH2)2PPh2 34.1 11.9 0.6 25 755 10 54 7 (C6F5)2P(CH2)2PM2 34.7 17.4 1.8 21 3698 29 172 CT5 (4-CF3-C6H4)2P(CH2)2P(4-CF3- 24.6 9.3 2.2 494 0 81 20 C6H4)2 8 (3 -CF3 -C6H4)2P(CH2)2M2 24.9 9.0 0.5 40 586 11 50 9 (3, 5-CF3 -C6H3)2PCH2CH2PPh2 19.9 7.2 1.0 220 566 24 31 (2,4,6-F3 -C6H2)2PCH2CH2M2 23.1 10.4 0.2 36 870 10 79 16 -1

Claims (9)

1. Claims: 1. A process for the production of a carboxylic acid by the

   carbonylation of an alcohol and/or a reactive derivative thereof, which process comprises reacting in the liquid phase carbon monoxide with a reaction composition comprising at least one alcohol and/or a reactive derivative thereof, a finite concentration of water, a halide co-catalyst and a catalyst system comprising a Group VIII noble metal and a bidentate ligand having the formula:-

   Z R' R 2 X - (Z)-Y R6 (1) wherein X and Y are independently either N, P, As, Sb, or Bi., R', R 2, R5 and R 6 are independently selected from alkyl, substituted alkyl, phenyl, substituted phenyl and the group of formula..

   (W)(W).(R 4)b wherein W is independently 0, N or S of valency m, (I1) R 3 is alkyl, substituted alkyl, phenyl or substituted phenyl, R 4 is either hydrogen or R3, a is a positive integer, and a + b = m; and Z is a divalent linking group, provided that WR 2 is not identical to WR6.
2. 2. A process as claimed in claim 1 in which the bidentate ligand has the 17 formula:- W' R 2' 18 X' - (CR"R 4')" _ Y Rs' 6' R (I) wherein X'and Y'are independently either nitrogen, phosphorus, arsenic, antimony or bismuth, at least one of R
3. 3 'and R 4' is (are) independently either hydrogen or hydrocarbyl; R", R2', W' and R" are independently selected from alkyl, substituted alICY1, phenyl and substituted phenyl, at least one of which is substituted by one or more electron withdrawing groups provided that W' R 2' is not identical to R" R 6 ', and n is an integer. 3. A process as claimed in claim 1 or claim 2 in which X and Y and X' and Y' are either nitrogen or phosphorous.
4. 4. A process as claimed in claim 2 or claim 3 is which both W' and R4' are hydrogen.
5. 5. 1.
6. 6. A process as claimed in which the electron withdrawing groups include halo substituents, preferably fluoro and groups having the formula:- A process as claimed 'In any one of claims 2 to 4 in which n is greater than 9 R (III) wherein at least R 7 - R9 is halo and the remainder, if any, is hydrogen.
7. 7. A process as claimed in claim 1 in which the bidentate ligand is selected from the group consisting of (i) (3 - F - C6H4)2P(CH2)2PM2 18 19 (ii) (3,5 - F2 - C6H3)2P(CH2)2P M2 (iii) (3,4,5 - F3 - C6H2)2P(CH2)2P M2 (iv) (3 -CF3 - C6H4)2P(CH2)2P M2 (v) (3,5 - CF3 - QHs)Y(CH2)2P M2 and (vi) (2,4,6 - F3 -C6H2)2P(CH2)2P Ph2
8. 8. A process as claimed in any one of the preceding claims in which the Group VIII noble metal is rhodium.
9. 9. A process as claimed in any one of the preceding claims in which the catalyst system includes a metal promoter component.

   19