GB2451325A

GB2451325A - Hydroformylation process

Info

Publication number: GB2451325A
Application number: GB0812778A
Authority: GB
Inventors: Hendrik Dirkzwager; Fredericus Jacobus Maria Kerkhof; Frederik Hendrik Van Der Steen
Original assignee: Shell Internationale Research Maatschappij BV
Current assignee: Shell Internationale Research Maatschappij BV
Priority date: 2007-07-24
Filing date: 2008-07-11
Publication date: 2009-01-28
Also published as: GB0812778D0

Abstract

A process for hydroformylation of vinylidene olefins, such as C16 vinylidene olefins, comprises of contacting the olefins with carbon monoxide and hydrogen in the presence of a catalyst system. The catalyst system comprises of a source of platinum group metal cations, such as platinum or palladium; a source of anions, other than halide anions, such as acids having a pKa value of less than 3, measured at 18{C in aqueous solution, such as anions of phosphoric acid, sulphuric acid, sulphonic acid and trifluoroacetic acid; and a source of bidentate ligands of the formula (I), R1R2M1RM2R3R4 (I). In formula (I), M1 and M2 is independently a phosphorous, arsenic or antimony, R is a bivalent organic bridging group containing 1-4 atoms in the bridge, such as an ethylene group, R1 and R2 is independently a substituted or unsubstituted hydrocarbyl group or together is a bivalent substituted or non-substituted cyclic group where the two free valencies are linked to M1, and R3 and R4 is a substituted or non-substituted hydrocarbyl group, or together is a bivalent substituted or non-substituted cyclic group where the two free valencies are linked to M2. The hydroformylation process is used for producing one or more primary alcohols comprising a carbon chain which is split into two branches at the C3 position.

Description

HYDROFORI4YLATION PROCESS

Field of the Invention

This invention relates to a process for the hydroformylation of vinylidene olef ins.

Background of the Invention

Various processes for producing aldehyde and/or alcohol compounds by the reaction of a compound having at least one olefinic carbon-to-carbon bond with carbon monoxide and hydrogen in the presence of a catalyst are known. Typically, these reactions are performed at elevated temperatures and pressures. The aldehyde and alcohol compounds that are produced generally correspond to compounds obtained by the addition of a carbonyl or carbinol group, respectively, to an clef inically unsaturated carbon atom in the starting material with simultaneous saturation of the clef in bond. These processes are typically known as hydroformylation reactions and involve reactions which may be shown in the general case by the following equation: R'R2C-.-CR3R4CHO R'R2CCR3R4 catalyst and/or + isomers thereof CO/H2 12 34 R R C-CR R CH2OH In the above equation, each group R' to R4 may independently represent an organic radical, for example a hydrocarbyl group, or a suitable atom such as a hydrogen or halogen atom, or a hydroxyl or alkoxy group. The above reaction may also be applied to a cycloaliphatic ring having an olefinic linkage, for example cyclohexene.

Conventional modes of operation were initially based on the use of a cobalt carbonyl catalyst. However, the activity of this catalyst is relatively low.

More recently, the catalyst employed in a hydroformylation reaction typically comprises a transition metal, such as cobalt, platinum, rhodium or ruthenium, in complex combination with carbon monoxide and ligand(s) such as an organophosphine.

Representative of the earlier hydroforrnylation methods which use transition metal catalysts having organophosphine ligands are described in US 3420898, US 3501515, US 3448157, US 3440291, US 3369050 and US 3448158.

In attempts to improve the efficiency of a hydroformylation process, attention has typically focussed on developing novel catalysts and novel processes for recovering and re-using the catalyst. In particular, novel catalysts have been developed which may exhibit improved stability at the required high reaction temperatures. Catalysts have also been developed which may permit the single-stage production of alcohols rather than a two-step procedure involving separate hydrogenation of the intermediate aldehyde. Moreover, homogeneous catalysts have been developed which may permit improved reaction rates whilst providing acceptable yields of the desired products.

When the olef in to be hydroformylated is a vinylidene olef in, as with all olef ins, isomerizatiorj of the olefin bond may take place to varying degrees under certain conditions (e.g. those suitable for hydroformylation) before hydroformylation occurs. As a consequence of this isomerjzatiorj, a variety of products may be obtained.

Figure 1 illustrates the range of products which may be obtained during the hydroformylation of a C16 vinylidene olef in. Product 1 will be produced when the non-substituted (hydrogen) end of the olef in is hydroformylated. Product 2 will be produced by hydroformylation on the substituted end of the olef in, leading to a quaternary carbon atom. When isomerisation takes place before hydroformylation, cis and trans jinternal olef ins will be formed and then hydroformylated, leading to an alcohol with a methyl branch in the carbon chain (for example, products 3 and 4). Further isomerisation will lead to a terminal or cx-olefin and thus the alcohols shown as products 5 and 6. A range of other products, formed from olefins wherein the double bond has migrated to a position between those which form 3 or 4 and those which form 5 or 6, are also possible.

A similar range of products may be obtained when using viriylidene olef ins of any chain length.

WO 01/30726 describes a method for the hydroformylation of vinylidene alcohols using a catalyst comprising cobalt neodecanoate and 9-eicosyl-phosphabicylononane. After fractional distillation, a fraction comprising 80 to 85% of monomethyl branched alcohols is obtained.

WO 97/00843 also describes a process for the hydroforrnylation of vinylidene alcohols using a catalyst comprising cobalt carbonyl and 9-phenyl--9-phosphabicyclononane. Such a process allows hydroformylation of the vinylidene olef in at the unsubstituted end of the olefin to produce a product equivalent to product 1 (see Figure 1), however with an undisclosed selectivity. After fractional distillation, the isolated fraction contains 75% of this desired -r product. The selectivity to product 1 with a similar cobalt catalyst to that disclosed in W097/00843 at the same conditions was only 33% in the crude reaction mixture at full conversion of a C16 vinylidene olef in It would be desirable to provide a more selective process to form products equivalent to product 1, i.e. a bifurcated primary alcohol, wherein the carbon chain is split into two branches at the C3 position, in the hydrofortnylation of vinylidene olef ins.

Further, a problem in many hydroformylation reactions is the formation of undesirable saturated hydrocarbon by-products. It would therefore be preferable to provide a process in which the formation of such by-products is suppressed.

Summary of the Invention

The present invention relates to a process for the hydroformylation of vinylidene olef ins, said process comprising contacting said olef ins with carbon monoxide and hydrogen in the presence of a catalyst system comprising: a) a source of platinum group metal cations; b) a source of anions, other than halide anions; and C) a source of bidentate ligands of the formula (I) R'R2M'RM2R3R4 (I) wherein M' and M2 independently represent a phosphorus, arsenic or antimony atom, R represents a bivalent organic bridging group containing from 1 to 4 atoms in the bridge, R' and R2 independently represent a substituted or unsubsticuted hydrocarbyl group or together represent a bivalent substituted or non-substituted cyclic group whereby the two free valencies are linked to M1 and R3 and R4 independently represent a substituted or non-substituted hydrocarbyl group, or together represent a

I p

bivalent substituted or non-substituted cyclic group whereby the two free valencies are linked to M2.

Brief Description of the Drawing

Figure 1 shows a range of products which may be obtained during the hydroformylation of a C16 vinylidene olef in.

Detailed Description of the Invention

It has surprisingly been found that primary alcohols comprising a carbon chain which is split into 2 branches at the C3 position may be formed in a selective manner by reacting vinylidene olef ins with carbon monoxide and hydrogen in the presence of a catalyst system comprising: a) a source of platinum group metal cations; b) a source of anions, other than halide anions; and C) a source of bidentate ligands of the formula (I) R'R2M'RN2R3R4 (I) wherein M1 and M2 independently represent a phosphorus, arsenic or antimony atom, R represents a bivalent organic bridging group containing from]. to 4 atoms in the bridge, R' and R2 independently represent a substituted or unsubstituted hydrocarbyl group or together represent a bivalent substituted or non-substituted cyclic group whereby the two free valencies are linked to M' and R3 and R4 independently represent a substituted or non-substituted hydrocarbyl group, or together represent a bivalent substituted or non-substituted cyclic group whereby the two free valencies are linked to M2.

Preferably, the process is carried out in the further presence of a catalyst promoter comprising a source of halide anions. Typically, if such a catalyst promoter is present, the molar ratio between halide and platinum group metal cations is in the range of from 0.02:1 to 3:1.

I p

Also preferably, the process is carried out in the presence of water in the range of from 0.6 wt', based on the total of the reaction mixture up to its solubility limit under the reaction conditions. More preferably, an amount of water in the range of from 0.7 to 3.Owt%, based on the total reaction mixture, is present.

In the present specification the metals of the

platinum group are defined as the metals with the atomic numbers 28, 46 and 78, i.e. nickel, palladium and platinum. Of these, palladium and platinum are preferred.

Most preferably, the metal is palladium.

Examples of suitable metal sources are platinum or palladium compounds such as salts of palladium and nitric acid, sulphuric acid or suiphonic acids, salts of platinum or palladium and carboxy].ic acids with up to 12 carbon atoms, palladium-or platinum complexes, e.g. with carbon monoxide or acetylacetonate, or palladium combined with a solid material such as an ion exchanger or carbon.

Palladium(II) acetate and platinum(II) acetylacetonate are examples of preferred metal sources.

As anion source, other than halide anions, any compound generating these anions may be used. Suitably, acids, or salts thereof, are used as source of anions, for example any of the acids mentioned above, which may also participate in the salts of the metals of the platinum group.

In the catalyst systems of the invention, preferably strong acids are used as anion source, i.e. acids having a pKa value of less than 3, preferably less than 2, measured in aqueous solution at 18 °C. The anions derived from these acids are non-coordinating or weakly coordinating with the metals of the platinum group.

P

Typical examples of suitable anions are anions of phosphoric acid, sulphuric acid, suiphonic acids and halogenated carboxylic acids such as trifluoroacetic acid.

Suiphonic acids are in particular preferred, for example methanesuiphonic acid, trifluoromethanesuiphonic acid, tert-butane-sulphonic acid, p-toluenesulphonic acid and 2,4, 6-trimethylbenzene-sulphonjc acid.

Complex anions are also suitable as an anion source, other than halide anions. Examples of suitable complex anions include those generated by a combination of a Lewis acid such as BF3, Aid3, SnF2, Sn(CF3SO3)2, SnC12 or GeC12, with a protic acid, such as a suiphonic acid, e.g. CF3SO3H or CH3SO3H or a hydrohalogenic acid such as HF or HC1, or a combination of a Lewis acid with an alcohol.

Examples of such complex anions are BF4, SnC1, [SnC12.CF3SO3] -and PF6.

In bidentate ligands of formula (I), i.e. component c of the catalyst system, M' and M2 are preferably the same and, more preferably, are both phosphorus atoms, in which case the ligands are bisphosphines.

In the organic bridging group, represented by R, typically all atoms in the bridge are carbon atoms.

Preferably the bridging group contains two carbon atoms in the bridge. It has been observed that the reaction rate is usually considerably enhanced if, instead of a catalyst based on a three-membered bridging group, for instance a trimethylene group, a catalyst is used based on a two-membered bridging group, for example an ethylene group.

In the ligands represented by formula (I), R1 and R2 may independently represent various non-cyclic or cyclic groups, optionally substituted with substituents such as p alkoxy groups with 1 to 4 carbon atoms, halogen atoms or (Cl to C4 alkyl)amino groups. Suitable examples include, but are not limited to, alkyl groups such as ethyl, isopropyl, sec-butyl and tert-butyl groups, cycloalkyl groups such as cyclopentyl and cyclohexyl groups, aryl groups such as pherxyl and tolyl groups and bivalent groups such as a hexan-iethylene group.

In a preferred embodiment, the bivalent (substituted) cyclic group, represented by R' together with R2, comprises at least 5 ring atoms and preferably contains from 6 to 9 ring atoms. More preferably the cyclic group contains 8 ring atoms. Substituents, if any, are usually alkyl groups having from 3. to 4 carbon atoms.

Suitably, all ring atoms are carbon atoms, but bivalent cyclic groups containing one or two heteroatoms in the ring, such as oxygen or nitrogen, atoms are not precluded. Examples of suitable bivalent. cyclic groups are 1,4-cyclohexylene, 1,4-cycloheptylene, 1,3-cycloheptylene, 1, 2-cyclo-octylene, 1,3-cyclooctylene, l,4-cyclooctylerie, l,5-cyclooctylene, 2-methyl-1,5- cyclooctylene, 2,6-dirnethyl-1,4-cyclooctylene and 2,6-dimethyl -1, 5-cyclooctylene groups.

Preferred bivalent cyclic groups are selected from l,4-cyclo-octylene, l,5-cyclooctylene, and methyl (di)substituted derivatives thereof.

Mixtures of ligands comprising different bivalent cyclic groups may also be used, e.g. mixtures of ligands with l,4-cyclooctylene and ligands with l,5-cyclooctylene groups.

In the ligands represented by formula (I), R3 and R4 may independently represent various non-cyclic or cyclic groups, optionally substituted with substituents such as alkoxy groups with 1 to 4 carbon atoms, halogen atoms or ii (Cl to C4 alkyl)ami.no groups. Suitable examples include, but are not limited to, alkyl groups such as ethyl, isopropyl, sec-buty]. and tert-butyl groups, cycloalkyl groups such as cyclopentyl and cyclohexyl groups, aryl groups such as phenyl and tolyl groups and bivalent groups such as a hexamethylene group. However, preferably R3, together with R4 represents a bivalent cyclic group, in particular the same group as the group represented by R' together with R2, in which case the two free valencies of the bivalent cyclic group are, of course, linked to M2, instead of M'. Thus, preferred bidentate ligands of formula (I) are 1,2-bis(1,4-cycloocty].ene-phosphino)ethane, 1,2-bis(l,5-cyclooctylene phosphino)ethane and mixtures thereof.

For the preparation of the bidentate ligands, reference is made to known techniques, for example the method disclosed in GB 1127965.

The quantity in which the catalyst system is used, is not critical and may vary within wide limits. Usually amounts in the range of l0 to 10', preferably in the range of 1O to 102 mole atom of platinum group metal per mole of ethylenically unsaturated compound are used.

The amounts of the participants in the catalyst system are conveniently selected such that per mole atom of platinum group metal from 0.5 to 10, preferably from 1 to 6 moles of bidentate ligand are used, from 0.5 to 15, preferably from 1 to 8 moles of anion source or a complex anion source.

In a preferred embodiment of the process of the invention a catalyst promoter, comprising a source of halide anions, may also be present. When such a promoter is used, the molar ratio between halide anions and platinum group metal cations should be at most 31.

SI

-10 -

I

If larger amounts of halide anions are present, the activity of the catalyst system is adversely affected.

Without wishing to be bound by theory, the adverse effect of the larger amount of halide anions may be due to co-ordination occurring between palladium and halide moieties.

Preferably, the molar ratio between halide anions and platinum group metal cations is at most 2:1, more preferably less than 1:1, for instance from 0.02:1 to 1:1.

As source of halide anions any compound generating halide anions under the reaction conditions may be used.

Recommended are inorganic compounds such as hydrogen halides, e.g. HC1, HBr and HI and metal halides, e.g. NaCl, MgBr2, ZnCl2, Zn12, KBr, RbC1, CsCl, CsI, MgI2 and CuC1.

Another category of recommended sources of halide anions consists of halogen containing organic compounds which are capable of providing halide anions to the reaction medium. Suitable are for example organic phosphonium halides, such as triarylalkyl phosphonium chloride and halogen containing aromatic compounds such as 5-halo-berizoic acids, e.g. 5-chlorobenzoic acid, 2,5- dichlorobenzoic acid, 2,3,5-tri--iodobenzoic acid, 3,5-di-iodobenzoic acid, m-halophthalic acids and esters thereof.

Catalyst promoters comprising a source of chloride anions are in particular preferred.

The term vinylidene olef in' as used herein has its standard definition, i.e. it is a compound of formula RARBCH=CH2, wherein RA and R3 are independently selected from optionally substituted hydrocarbyl groups.

-11 -

I

Preferably, in the present invention R and RB are independently selected from alkyl groups. Most preferably, RA and RB are independently selected from alkyl groups having carbon numbers in the range of from 2 to 20, preferably from 4 to 16. R and RB are suitably linear alkyl groups, but may also contain branching.

Viriylidene clef ins suitable for use in the present invention may be formed by any suitable method known in the art. Typically the vinylidene clef ins are made by dimerisation of a-olef ins under selective conditions (see, for example WO 01/30726 and WO 97/00843) . Such a reaction forms vinylidene olef ins according to the following equation: R'CH=CH2 + R"CH=CH2 CH2=C (Rc) CH2CH2R + CH2=C (R) CH2CH2RX wherein Rx and R may be different or the same. Thus, a mixture of cx-olef ins will produce a mixture of vinylidene olef ins.

Suitable cx-olef ins may be formed by any suitable method known in the art, in particular, they may be formed by subjecting a synthesis gas comprising carbon monoxide and hydrogen to Fischer-Tropsch reaction conditions in the presence of a suitable Fischer-Tropsch catalyst.

The desired products of the process of the present invention are primary alcohols comprising a carbon chain which is split into 2 branches at the C3 position. That is, the vinylidene clef in is hydroforrnylated at the non-substituted (hydrogen end) according to the following equation: R1R' R -12 -ft In the process of the present invention, carbon monoxide and hydrogen may be supplied in equimolar or non-equitnolar ratios, e.g. in a ratio within the range of 5:1 to 1:5, typically 3:1 to 1:3. Preferably they are supplied in a ratio within the range of 2:1 to 1:2.

The hydroformylation can be suitably carried out at moderate reaction conditions. Hence temperatures in the range of 50 to 200 °C are recommended, preferred temperatures being in the range of 70 to 160 °C. Reaction pressures in the range of 5 to 100 bar are preferred, lower or higher pressures may be selected, but are not considered particularly advantageous. Moreover, higher pressures require special equipment provisions.

In the process of the invention, the ethylenically unsaturated starting material and the formed hydroforrnylatjon product may act as reaction diluent.

Hence, the use of a separate solvent is not necessary.

Conveniently, however, the hydroformylation reaction may be carried out in the additional presence of a solvent.

As such, saturated hydrocarbons, e.g. paraf fins and isoalkaneg are recommended and furthermore alcohols, preferably having from 4 to 10 carbon atoms per molecule, such as butanol, ethylhexanol-i, nonanol-1, or in general terms the alcohols formed as hydroformylation product; ethers such as 215,8-trioxanonane (diglyme), diethylether and anisole, and ketones, such as methylbutylketone.

It is also advantageous, if the hydroformylation process is carried out in a homogeneous reaction medium using a dissolved catalyst system of adequate activity, whereby the catalyst can be readily recovered and reused, without significant loss or decomposition thereof, if so desired.

-13 -Accordingly, a preferred embodiment of the invention relates to a process for the hydroformylation of vinylidene olef ins by reaction thereof with carbon monoxide and hydrogen in a single-phase liquid medium in the presence of the aforementioned catalyst system, followed by effecting the formation of a multiphase liquid reaction medium comprising one phase in which substantially all platinum group metal cations of the catalyst system are present and at least one further phase containing a major portion of the hydroformylated product.

The formation of the multiphase liquid reaction medium, following the hydroformylation reaction, can be effected in various ways.

For example, a selective solvent for the hydroformylated product may be added to the single-phase liquid reaction mixture during or subsequent to the hydroformylation reaction, thereby forming a second liquid phase in which a major portion of the hydroformylated product, and possibly part of any unconverted unsaturated starting material, will be found.

Whereas in this embodiment two liquid phases are formed allowing an adequate separation between the catalyst system on the one hand and a major portion of the hydroformylation product on the other hand, it will be necessary to remove the hydroformylated product from the said second liquid phase containing the added solvent.

Therefore, it is preferred to effect the formation of a multiphase liquid reaction medium by adding an inert solvent capable of selectively dissolving substantially all platinum group metal of the catalyst system to the single-phase liquid reaction medium during or subsequent to the hydroformylation reaction. This embodiment allows an adequate separation between the hydroformylated product and the catalyst system, whilst, at the same time, simplifying the recovery of the hydroformylated product.

According to a still more preferred embodiment, the hydroformylation reaction is carried out in the presence of an inert solvent and, subsequent to the reaction, the multiphase liquid reaction medium is formed by cooling the reaction medium obtained in the reaction.

In this manner it is possible to ensure, that substantially all platinum group metal of the catalyst system, i.e. at least 95% and in particular at least 97% of the platinum group metal, is present in the liquid phase containing the inert solvent.

A major portion of the hydroformylated product, i.e. at least 50% and in particular at least 80% of the hydroformylated product is obtained in another liquid phase from which it can be easily recovered by known techniques.

By selection of a suitable solvent the multiphase liquid medium is readily formed when the temperature of the reaction mixture is decreased to ambient temperature.

If desired, the reaction medium can be cooled to lower temperatures. However, for large-scale operation this is not considered of special advantage in view of the additional provisions to be made in the reactor sedtion of the equipment.

Suitable inert solvents which may be added instead of, or in addition to, the solvents mentioned above, that are capable of selectively dissolving substantially all platinum group metal of the catalyst system, are usually -15 -characterized by the presence of an aprotic, polar group in the molecule.

Solvents comprising, or substantially consisting of, suiphones are preferred. Suiphones are in particular preferred, for example dialkylsuiphones such as dimethylsulphone and diethylsuiphone and cyclic suiphones, such as sulfolane (tetrahydrothiophene-2,2- dioxide), sulfolene, 2-methylsulfolane arid 2-methyl-4-ethylsulfolane.

Sulfolane has proved to be a most effective solvent for the formation of a multiphase liquid reaction medium.

It is particularly beneficial to carry out the invention using sulfolane as solvent and a catalyst system based on a complex anion (for instance based on SnC12) and/or in the presence of a catalyst promoter, to counter the somewhat increased paraffin formation due to presence of the solvent.

Mixtures of solvents may also be used, for example a mixture of a suiphone with a protic solvent, such as an alcohol. In the hydroformylation of olefins, typically an alcohol is selected which is identical or similar to an alcohol as obtained in the hydroformylation reaction.

The amount of solvent to be used in the process of the invention may vary considerably. It is within the reach of those skilled in the art to establish in each case the degree of cooling and the optimal amount of solvent required for the formation of a rnultiphase liquid reaction medium.

The invention will now be illustrated by the following, non-limiting examples.

Examples

The following Examples were all carried out under the conditions set out herebelow.

A Cl6 vinylidene olef in, formed by dimerisation of C8 a-olefins and measured as 98 wt% or more purity by GC and 3C NMC, was obtained from Shell Chemicals. Cobalt octanoate (9.7wt% Co in 2-ethyihexanol) and 9-eicosyl-9-phosphabicyclononane were used in comparative experiments 2 to 4. Palladium acetate (ex. Acros) and l,2-bis(9-phosphabicylonyl)ethane (ex. Cytec) were used in Example 1 (of the invention).

Example 1

A 300 ml Hastelloy autoclave was charged with 58.0 g of C16 vinylidene olefin, 53.7 g 2-ethylhexanol, 2.0 g of tetradecane (internal standard) and 2.0 g of water. The autoclave was purged with nitrogen, heated to 105 °C and pressured to 70 barg with syngas (H2/CO ratio = 2.0). To start the experiment 20 g of a sulfolane solution containing pre-prepared palladium catalyst with a molar ratio of palladium acetate: 1,2-bis(9-phosphabicylonyl)ethane: HC1: HOtf of 1.0: 1.05 0.4 1.7 was injected and a t=0 sample was taken. The starting composition of the autoclave is substantially equal to 40 %w 2-ethyihexanol, 15 %w sulfolane, 1.6 %w water, 1.5 %w internal standard, 42 %w C16 olef in and 200 ppmw palladium. Samples were withdrawn at regular time intervals and analyzed by GC to determine conversion and selectivity. After 4 hours reaction 76% of the C16 vinyuidene olef in was converted into alcohols (98.0 %w), aldehydes (1.9 %w) and paraff ins (0.]. %w) The product distribution of the C17 alcohol fraction was as follows: 77.1 %w 3-hexyl-undecanol-i. (product 1), 4.8 %w various monomethyl branched alcohols (product 3 & -17 - 4) and 18.2 %w 8-methyl-hexadecanol-i and 10-methyl-hexadecanol-a. (products 5 & 6).

Comparative Example 2 Comparative Example 2 relates to a cobalt catalyst similar to that disclosed in W097/00843. A 300 ml Hastelloy autoclave was charged with 71.4 g of C16 vinylidene olefin, 51.6 g 2-ethyihexanol, 4.07 g of a 5 %w solution of KOH in 2-ethyihexanol, 2 g of tetradecane (internal standard) . The autoclave was purged with nitrogen and heated to 200 °C and pressured to 70 barg with syngas (H2/CO ratio = 2.0). To start the experiment 14.3 g of 2-ethyihexanol solution containing cobalt octoate (14.6 %w) and 9-eicosyl-9-phosphabicyclononane (24.0 %w) was injected and a t=0 sample was taken. The resulting catalyst composition was 0.25 %w Cobalt, with a molar ratio of 9-eicosyl-9-phosphabicyclononane to Co of 1.3 and a molar ratio of KOH to Co of 0.6. Samples were withdrawn at regular time intervals and analyzed by GC to determine conversion and selectivity. After 4 hours reaction 91% of the C].6 vinylidene olefin was converted into alcohols (91.4 %w), aldehydes (2.3 %w) and paraff ins (6.3 %w).

The product distribution of the C17 alcohol fraction was as follows: 28.9 %w 3-hexyl-undecanol-1 (product 1), 8.5 %w various rnonomethyl branched alcohols (product 3 & 4) and 62.6 %w 8-rnethyl-hexadecanol-i and 10-methyl-hexadecanol-l (products 5 & 6).

Comparative Example 3 (according to WO 97/00843) Following the same procedure as in Comparative Example 2 an experiment with a molar 9-eicosyl-9-phosphabicyclononane to cobalt ratio of 2.0 without KOH (molar ratio of KOH:cobalt is 0) at 200 °C was carried out. After 4 hours reaction only 32% of the C16 -18 -vinylidene olef in was converted into alcohols (90.6 %w), aldehydes (2.6 %w) and paraf fins (6.8 %w).

The product distribution of the C17 alcohol fraction was as follows: 51.0 %w 3-hexyl-undecanol-l (product 1), 2.6 %w various monomethyl branched alcohols(product 3 & 4) and 44.9 %w 8-methyl-hexadecanol-1 and 10-methyl-hexadecanol-1 (products 5 & 6). This product selectivity is perceptive as the selectivity at low conversion is different from the selectivity at high olefin conversion.

After 45 hours reaction 99% conversion of C16 vinylidene olef in was reached: 92 %w alcohols, 1.3 %w aldehydes and 6.7 %w paraff ins. The product distribution of the C17 alcohol fraction was as follows: 32.6 %w 3-hexyl-undecanol-1 (product 1), 3.9 %w various monomethyl branched alcohols(product 3 & 4) and 63.5 %w 8-methyl-hexadecanol-1 and l0-methyl-hexadecanol--1 (products 5 & 6) Comparative Example 4 (According to WO 01/30726) Following the same procedure as in Example 2 an experiment with a molar 9-eicosyl-9-phosphabicyclononane cobalt ratio of 2.6 at 170 °C was carried out. After 4 hours reaction only 32% of the C vinylidene olef in was converted into alcohols (88.8 %w), aldehydes (4.0 %w) and paraffins (7.2 %w) The product distribution of the C17 alcohol fraction was as follows: 53.6 %w 3-hexyl-undecanol-1 (product 1), 2.8 %w various monomethyl branched alcohols(product 3 & 4) and 43.6 %w 8-methyl-hexadecanol-]. and 10-methyl-hexadecanol-1 (products 5 & 6). This product selectivity is perceptive as the selectivity at low conversion is different from the selectivity at high clef in conversion.

Without wishing to e bound by theory, the selectivity at high olefin conversion is expected to be closer to the selectivity shown in Comparative Example 3.

In summary, the process of the present invention

provides a selective method for the hydroformylation of vinylidene olef ins in order to form bifurcated alcohols, wherein the carbon chain is split at the C3 position.

A further advantage of the process of the present invention is the low paraffin make observed in the hydroformylat ion process.

Claims

-20 -a CLAIMS

1. A process for the hydroformylation of vinylidene olef ins, said process comprising contacting said olef ins with carbon monoxide and hydrogen in the presence of a catalyst system comprising: a) a source of platinum group metal cations; b) a source of anions, other than halide anions; and c) a source of bidentate ligands of the formula (I) R'R2M'RM2R3R4 (I) wherein M1 and M2 independently represent a phosphorus, arsenic or antimony atom, R represents a bivalent organic bridging group containing from 1 to 4 atoms in the bridge, R' and R2 independently represent a substituted or unsubstituted hydrocarbyl group or together represent a bivalent substituted or non-substituted cyclic group whereby the two free valencies are linked to M1, and R3 and R4 independently represent a substituted or non-substituted hydrocarbyl group, or together represent a bivalent substituted or non-substituted cyclic group whereby the two free valencies are linked to M2.

2. The process of claim 1, wherein the vinylidene olef in has been obtained by the dimerisation of one or more a-olefins.

3. The process of claim 1 or claim 2, wherein the platinum group metal is selected from platinum and * 25 palladium.

4. The process of any one of claims 1 to 3, wherein in the source of bidentate ligands of formula (I), M' and M2 each represent a phosphorous atom.

5. The process of any one of claims 1 to 4, wherein R represents an ethylene group.

-21 -

6. The process of any one of claims 1 to 5, wherein in the bidentate ligand of formula (I), R' and R2 together represent a bivalertt cyclic group comprising a cyclo-alkylene group having from 6 to 9 ring atoms.

7. The process of claim 6, wherein in the bidentate ligand of formula (I), R3 and R4 together represent a bivalent cyclic group comprising a cyclo-alkylene group having from 6 to 9 ring atoms.

8. The process of any one of claims 1 to 7, wherein the process is carried out in the further presence of a S catalyst promoter comprising halide anions.

9. The process of any one of claims 1 to 8, wherein the source of anions, other than halide ions, is selected from acids having a pKa value of less than 3, measured in aqueous solution at 18 °C.

10. The process of any one of claims 1 to 9, wherein the product of said process is one or more primary alcohol comprising a carbon chain which is split into 2 branches at the C3 position.