Background The carbonylation of hydrocarbons is a process in which the carbonyl group is added to the double bond of a hydrocarbon thereby to produce oxygenates such as aldehydes, ketones and alcohols.

The addition of the units H and CHO to double bonds is also classified as a type of carbonylation process and represents one of the largest industrial applications of soluble transition-metal catalysts. The processes used are mainly based on either homogeneous cobalt or rhodium catalyst systems.

The process is frequently referred to as the"oxo"process, with oxo being short for oxonation, i e the addition of oxygen to a double bond. However, the term hydroformylation is descriptively more accurate and probably more useful in characterizing this type of reaction.

Processes using unmodified catalyst systems, i. e. no added inert ligands, like cobalt carbonyl catalysts are operated with temperatures typically in the range of 110°C to 180°C and with pressures in the range 200 to 350atm. The cobalt catalyst precursor is initially fed into the reactor as cobalt salts, e. g. cobalt acetate, cobalt carbonyls e. g. Co2 (CO) s or even cobalt metal. In the 1960s Slaugh and Mullineaux, working in Shell Oil's laboratories in California, discovered that by adding tertiary phosphine ligands to cobalt carbonyl systems, complexes were formed, which did not depend on high CO pressures for their stability and which were able to catalyze the conversion of alk-1-enes to normal alcohols with over 90% selectivity. E. g. cobalt carbonyl hydroformylation catalysts containing alkyl tertiary-phosphines, e. g. PBu3, are operated at H2/CO pressures as low as 5 to 10 atm and may be used for

reaction temperatures in the range 100 to 180°C. These also have a greater hydrogenation activity thus giving rise to alcohol rather than aldehyde products under hydroformylation conditions. With linear a-olefins as substrate, normal to iso-alcohol ratios are typically twice those obtained using unmodified catalysts, e. g. 8: 1 compared to 4: 1. On the negative side however, the activity of these complexes is considerably lower than that encountered with cobalt carbonyl catalysts not containing phosphine ligands ; at 145°C hydroformylation with an unmodified catalyst is some five times faster than that obtained with the modified one at 180°C.

Rhodium is a much more active hydroformylation metal than cobalt, it is capable of effectively operating under much milder conditions, (temperature and pressure). As with the unmodified cobalt systems the rhodium can be introduced into the reaction medium in a number of forms, e. g. rhodium on a support, as a chloro or carboxylic salt or as a metal-carbonyl complex such as Rh4 (CO) zu or Rh2 (CO) 4CI2, all of which under the hydroformylation conditions (70-150°C and 50-150 atm total pressure, H2 : CO = 1 : 1), form the catalytically active species, RhH (CO) 3. The major breakthrough in the commercial application of rhodium based hydroformylation systems occurred in the early sixties when Slaugh and Mullineaux of Shell Oil's Emeryville laboratories disclosed the use of trialkyl-phosphine and arsine complexes of rhodium as alkene hydroformylation catalysts. Generally, phosphine containing rhodium catalysts are operated at very mild conditions, ~100°C and ~35 atm CO: H2 pressure. Unlike cobalt the rhodium systems exhibit little or no aldehyde hydrogenation activity and thus the final reaction mixture contains almost no alcohols.

Other metals that have been used in hydroformylation are ruthenium containing complexes like Ru (CO) s (PPh3) 2, which is operated under fairly rigorous conditions like 120°C and 100 atm 1: 1 CO: H2. Typically, alkene to aldehyde selectivies of around 99% have been achieved, although the normal-iso ratio seldom exceeds 3: 1.

Shell Oil Company has a recent invention in which palladium is used in hydroformylation reactions. The catalyst system is a combination of: (a) A group VIII metal cation, (Pd and Pt), (b) A compound acting as bidentate ligand of formula R1R2M1-M2R3R4 wherein M1 ånd M2 independently are P, As or Sb. R represents a substituted or non-substituted bivalent group containing 1 to 5 atoms in the bridge. R'and R2 are a substituted or non-substituted bivalent group, furthermore, the two free valencies are linked to M1. R3 and R4 together are a substituted or non-substituted bivalent group whereby the two free valencies are linked to M2 or R3 and R4 independently are substituted or non-substituted hydrocarbon groups, and (c) A source of anions. Suitably acids are used as the source of anions or the salts thereof, e. g. anions derived from Bronsted acids such as from phosphoric acid and sulphuric acid and in particular sulphonic acid and (halogenated) carboxylic acids, such as trifluoroacetic acid. Complex anions generated by a combination of a Lewis acid such as BF3, B (C6F5) 3, AIC13, etc. combined with a protic acid eg. CF3SO3H or CH3SO3H or a halogenic acid such as HF or HCI are also suitable.

The reaction is carried out in the temperature of range of 100°-200°C and pressure range of 1 to 200 bar. The selectivities from 1-octene to Cs-alcohols depend on the type of ligand used.

Due to the paucity of options and the various drawbacks from whichs each suffers, the inventors have sought to provide a further carbonylation catalyst having catalytic activity and selectivity of an acceptable level.

As yet the potential of gold as a hydroformylation catalyst has been left largely unexplored. Gold has been employed in hydroformylation in polymer supported mixed metal clusters. The iron-cobalt-gold pentametallic clusters, (POL-C6H4CH2-PPh2Au-, u3) FeCo3 (CO) 12, where POL = poly (styrene- divinylbenzene), as well as the homogeneous analogue, PPh3Au- p. 3) FeCo3 (CO) 12 were used for the production of n-heptyl aldehyde in the hydroformylation of 1-hexen. The supported clusters were found to be more

stable and selective than the homogeneous cluster. The activities were found to increase with an increase in temperature, with 83.9 mol% conversion at 160°C and 30kg/cm2 1: 1 syngas pressure. The selectivities in mol% were found to be 99%.

Summary of the Invention Thus, according to a first aspect of the invention, there is provided an organometallic complex containing gold metal for use as catalyst in a carbonylation process. The carbonylation process may be a hydroformylation process.

Phrased differently, according to a first aspect of the invention, there is provided a carbonylation catalyst for carbonylating olefins, said catalyst containing an organometallic complex containing gold metal. The catalyst may be in an unsupported homogeneous form. The organometallic gold complex containing gold metal may be a monometallic gold complex.

The carbonylation catalyst may be a hydroformylation catalyst for hydroformylating olefins.

The invention extends to the use of unsupported, homogeneous, monometallic gold complexes as catalyst for the hydroformylation of olefins.

Yet further, the invention extends to the use of the gold complexes as isomerization and hydroformylation catalyst for the production of alpha aldehydes from olefins. Typically the olefins are internal or a-olefins.

Typical carbonylation process conditions using the above catalyst are in the temperature range of 40°C-200°C and pressure range of 10-500 bar.

However, at present, an operation temperature of 110°C and an operating pressure of 60 bar is preferred. Further experiments may however provide yet

other more preferred operating conditions and thus the invention is not limited to any particular combination of operating temperatures and pressures.

Using the catalyst a synthesis gas of a 1: 1 ratio (CO: H2, (50%: 50%), as well as that of a 2: 1 ratio (H2: CO, 33%: 66%) may be used for the carbonylation of olefins, however, at present better results are obtained when using the 2: 1 ratio synthesis gas.

The catalyst appears suitable for the hydroformylation of olefins in the range of ¬2-Cis. These olefins include olefins with double bonds in the alpha position, internal double bonds and branched olefins.

The invention extends also to a carbonylation catalyst system including a gold metal cation; a compound acting as a ligand, which ligand has the property of being a good leaving group thereby to expose a co-ordination position on the gold metal cation for the carbonylation reaction to proceed.

Typical ligands include all phosphines, monodentate as well as bidentate, all phosphites, monodentate as well as bidentate.

The carbonylation catalyst system may be suitable for hydroformylation of olefins to aldehydes.

Gold complexes of the oxidation states I and III may be employed as catalyst system precursors.

Specific Description of the Invention The invention is illustrated by way of examples given below, these examples are not meant to be limiting.

Examples 1) A gold complex containing trimethylphosphine as a monodentate phosphine ligand and an excess of triphenylphosphine were added to an autoclave containing 1-octene. The temperature was allowed to stabilize at 90°C. The autoclave was pressurized to 330 psi with a 1: 1 syngas mixture. The reaction was maintained for about 24hr, after which it become evident that hydroformylation started taking place. The n: iso ratio of the reaction products were 3: 1.

2) A gold complex containing trimethylphosphine as a monodentate phosphine ligand and an excess of triphenylphosphine were added to an autoclave containing 100ml of 1-octene. The temperature was allowed to stabilize at 100°C. The autoclave was pressurized to 540 psi with a 1: 1 H2 : CO syngas mixture. Slow gas consumption was observed and after about 19 hr hydroformylation started taking place. The reaction was monitored for a further 7 hr, during which time it became evident that the rate at which hydroformylation took place was about double that in reaction 1.

3) Two runs were done in order to determine the induction time for the formation of the catalytically active species. The runs were carried out under the following conditions: Run A: The gold complex containing trimethylphosphine as the monodentate phosphine ligand and an excess of of triphenylphosphine was added to an autoclave containing 1-octene. The temperature was stabilized at 100°C, after which the autoclave was pressurized to 540 psi with syngas 1: 1, H2: CO = 1: 1

Run B : The procedure in Run A was repeated, with the exception that the autoclave was pressurized to 540 psi with 2: 1 syngas, H2: CO = 2 : 1 The reactions were monitored over time. In the case of run A no hydroformylation was evident after 7hr, whereas hydroformylation was detected after 4.5 hr in run B. The rate of gas consumption also increased after hydroformylation had begun. This is an indication that the formation of the hydride complex is a rate limiting step in the formation of the active species.

4) A gold complex and an excess of the ligand, triphenylphosphine were added to an autoclave containing 1-octene. The temperature was allowed to stabilise at 100°C after which the reactor was pressurized to 640psi with 2: 1, H2 : CO ratio syngas. The hydroformylation of 1-octene started after 3hrs.

5) A gold complex containing triphenylphosphine as a monodentate phosphine ligand and an excess of triphenylphosphine were added to the autoclave containing 1-octene. The temperature was stabilised at 100°C after which the reactor was pressurized to 640 psi. The reaction was left for 3 days, after which a GC spectrum revealed that isomerization of the feed had taken place before hydroformylation.

6) A gold complex containing triphenylphosphine as a monodentate phosphine ligand and an excess of triphenylphosphine were added to the autoclave containing 1-octen. The temperature was stabilised at 120°C after which the reactor was pressurized to 820 psi. In this case only hydroformylation took place and no isomerization.

7) A gold complex containing triphenylphosphine as phosphine ligand was used under hydroformylation conditions with the temperature at 100°C and the pressure at 820 psi. Again only hydroformylation and no isomerization took place.

8) A gold complex containing tricyclohexylphosphine as phosphine ligand was added to an autoclave with an excess of the free ligand and 1-octene as the feed. The temperature was left to stabilize at 110°C, after which the reactor was pressurized to 820psi. Hydroformylation started after about 26 hours, without any isomerization being evident.

9) A gold complex containing tricyclohexylphosphine as phosphine ligand was added to an autoclave with an excess of the free ligand and 1-octene as the feed. The temperature was stabilized at 120°C after which the reactor was pressurized to 640 psi. The reaction was left for 3 days, after which a GC spectrum revealed that isomerization of the feed had taken place before hydroformylation.

10) A gold complex containing the bidentate ligand, 1,2-bis (diphenyl- phosphino) ethane, (ddpe), of the formula, (acac) MdppeM (acac) was synthesized and and tested as hydroformylation catalyst with 1-octene as the feed. The temperature was allowed to stabilize at 110°C, after which the autoclave was pressurized to 820psi. After 48hrs hydroformylation of the feed was observed.

11) A gold complex containing dimethylphenylphosphine was used as the phosphine ligand under hydroformylation conditions with 1-octene as the feed. The temperature was stabilized at 100°C, after which the autoclave was pressurized to 820 psi. Hydroformylation of the feed started after 3.5 hrs.

The conditions, conversions and selectivities for each example are summarized in Table 1.

Table 1: Conversions and selectivities Example M/Ligand Syngas T P induction Conversion Selectivity Number Composition (°C) psi Time % (after (n : iso) 1 hr) 1 Au/PMe3 1: 1 90 330 24 26 4 : 1 2 Au/PMe3 1: 1 100 540 19 28 4 : 1 3 (a) Au/PMe3 1: 1 100 540 7 26 4: 1 (b) Au/PMe3 2: 1 100 540 4.5 24 4: 1 4 Au/PMe3 2 : 1 100 640 3 30 4 : 1 5 Au/PPh3 2: 1 100 640 24 (Isom) 26 72 (Hf) 5 3 : 1 6 Au/PPh3 2: 1 120 820 5 25 4 : 1 7 Au/PPh3 2: 1 100 820 7 10 4 : 1 8 Au/PCy3 2: 1 110 820 26 27 4 : 1 9 Au/PCy3 2: 1 120 640 30 (Isom) 22 72 (Hf) 8 2 : 1 10 Au/dppe 2: 1 110 820 48 10 4 : 1 11 Au/PMePh2 2: 1 100 820 3.5 30 4: 1 Isom: Isomerization before hydroformylation Hf: Hydroformylation only On comparing the monodentate phosphine ligands used in the hydroformylation reactions a definite pattern is observed; the bulkiness of the phosphine ligand has an effect on the induction time needed to form the active catalytic species in a syngas atmosphere, as indicated in Table 2.

Table 2 : Effect of cone angle and basicity on the induction time Ligand Cone angle (0) Induction time TOF PMe3 118 3 hr 200 PMe2Ph 122 3. 5hr 200 PPh3 145 5hr 170 PCy3 170 26hr 160

TOF = turnover frequency