WO2012072594A1

WO2012072594A1 - Ligand, catalyst and process for hydroformylation

Info

Publication number: WO2012072594A1
Application number: PCT/EP2011/071206
Authority: WO
Inventors: Marijke De Boer-Wildschut; Manutsavin Charernsuk; Cornelia Alida Krom; Paul Gerard Pringle
Original assignee: Shell Internationale Research Maatschappij BV
Current assignee: Shell Internationale Research Maatschappij BV
Priority date: 2010-11-30
Filing date: 2011-11-28
Publication date: 2012-06-07
Anticipated expiration: 2013-05-30

Abstract

The invention relates to an organophosphine ligand comprising a phosphabicyclohydrocarbyl group in which the phosphorus atom of the phosphabicyclohydrocarbyl group is further substituted with a heterohydrocarbyl moiety containing at least one phosphorus oxide [P=O] group or sulfur oxide [S=O] group. The invention also relates to a catalytic composition for the hydroformylation of an ethylenically unsaturated compound, comprising a source of Group VIII metal cations and said organophosphine ligand. Furthermore, the invention also relates to a process for the hydroformylation of an ethylenically unsaturated compound comprising contacting the latter compound with carbon monoxide and hydrogen in the presence of said catalytic composition.

Description

LIGAND, CATALYST AND PROCESS FOR HYDROFORMYLATION

The present invention relates to a ligand and a catalyst suitable for use in the hydroformylation of ethylenically unsaturated compounds. It also relates to a process for the hydroformylation of ethylenically

unsaturated compounds.

Various processes for producing aldehyde and/or alcohol compounds by the reaction of an ethylenically unsaturated compound 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 olefinically unsaturated carbon atom in the starting material with simultaneous saturation of the olefin bond. Isomerization of the olefin bond may take place to varying degrees under certain conditions; thus, as a consequence of this isomerization, a variety of products may be obtained. These processes are

typically known as hydroformylation reactions and involve reactions which may be shown in the general case by the following equation:

catalyst

R¹R²C=CR³R⁴ + CO + H₂ ^> R¹R²CH-CR³RCHO +

R¹R²CH-CR³RCH₂OH and/or isomers thereof

In the above equation, each group R¹ 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 group. The above reaction may also be applied to a cycloaliphatic ring having an olefinic linkage, for example cyclohexene.

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

Representative of the earlier hydroformylation methods which use transition metal catalysts having organophosphine ligands are described in US3420898,

US3501515, US3448157, US3440291, US3369050 and US3448158.

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.

Phosphabicyclohydrocarbyl ligands are known in the art, and their production and use in hydroformylation reactions are for example described in WO200494440,

WO200382779, WO200368719, WO200368786, US7012162,

WO200052017, WO200703589, WO200456732, WO200454946 and US20100036171.

Said US20100036171 discloses

phosphabicyclohydrocarbyl ligands in which the phosphorus atom is further substituted with a hydrocarbyl or

heterohydrocarbyl moiety containing at least one branch at the β-carbon position. More specifically, said

US20100036171 discloses organophosphine ligands of the following formula:

wherein m = 1, 2 or 3 and n = 1, 2 or 3, with the proviso that m + n < 4 and R⁶ is a cyclic group. Mentioned examples of R⁶ are tetrahydrofuran, cyclohexane and tetrahydropyran groups .

Although the use of organophosphine ligands and organophosphine-modified metal catalysts provide very good results in the hydroformylation of ethylenically unsaturated compounds, the use of such ligands and catalysts is known to lead to the production of paraffins as a by-product. The paraffin by-products have very little commercial value. It would, therefore, be

desirable to reduce the amount of paraffin by-products formed in a hydroformylation process. Further, it would be desirable to provide an improvement in the activity or reaction rate of a hydroformylation reaction over that catalysed by known metal catalyst systems.

It has now surprisingly been found that the amount of by-product paraffins produced in the hydroformylation reaction of an ethylenically unsaturated compound can be reduced and the reaction rate of such a reaction can be increased by using an organophosphine ligand wherein the phosphorus atom of the phosphabicyclohydrocarbyl group is further substituted with a heterohydrocarbyl moiety containing at least one P=0 or S=0 group.

Accordingly, the invention relates to an

organophosphine ligand comprising a

phosphabicyclohydrocarbyl group in which the phosphorus atom of the phosphabicyclohydrocarbyl group is further substituted with a heterohydrocarbyl moiety containing at least one phosphorus oxide [P=0] group or sulfur oxide [S=0] group.

The invention also relates to a catalytic composition for the hydroformylation of an ethylenically unsaturated compound, said catalytic composition comprising

i) a source of Group VIII metal cations; and

ii) the above-mentioned organophosphine ligand.

Furthermore, the invention also relates to a process for the hydroformylation of an ethylenically unsaturated compound, said process comprising contacting the

ethylenically unsaturated compound with carbon monoxide and hydrogen in the presence of the above-mentioned catalytic composition.

In the present invention, the phosphorus atom of the phosphabicyclohydrocarbyl group containing ligand is substituted with a heterohydrocarbyl moiety, which moiety contains a P=0 or S=0 group, preferably a P=0 group.

Preferably, the heteroatoms from said P=0 group and S=0 group are the only heteroatoms in said heterohydrocarbyl moiety. Further, preferably, the P=0 or S=0 group is at the beta-, gamma-, delta- or epsilon-position, more preferably the beta-position, of the heterohydrocarbyl moiety .

Further, preferably, the ligand of the present invention is of Formula (I) :

Formula (I)

wherein m = 1, 2 or 3 and n = 1, 2 or 3, with the proviso that m + n is less than or equal to 4, and R represents the remainder of the ligand. That is, the phosphabicyclohydrocarbyl group is selected from the group consisting of 6-phosphabicyclohexyl , 7- phosphabicycloheptyl , 8-phosphabicyclooctyl and 9- phosphabicyclononyl groups, with the proviso that the smallest phosphorus-containing ring in the

phosphabicyclohydrocarbyl group contains at least 5 atoms. Any structural isomer of such compounds, e.g. the [3.3.1] and [4.2.1] isomers of a 9-phospha-bicyclononyl group, are suitable in the present invention. Preferably, m = 3 and n = 1 ( 9-phospha-bicyclo [ 4.2.1 ] nonyl ) or m = 2 and n = 2 ( 9-phospha-bicyclo [ 3.3.1 ] nonyl ) . It is also envisaged that the ligand of the present invention comprises a mixture of a ligand of Formula (I) wherein m = 3 and n = 1 and a ligand of Formula (I) wherein m = 2 and n = 2.

Each carbon atom within the phosphabicyclohydrocarbyl group of the ligand of the present invention may

independently be substituted or unsubstituted . Suitable substituents include hydrocarbyl groups,

heterohydrocarbyl groups and/or groups comprising hetero- atoms .

As used herein, hydrocarbyl refers to groups

containing only hydrogen and carbon atoms. Such groups may be saturated or unsaturated, branched or unbranched and may contain aromatic and/or aliphatic moieties.

As used herein, heterohydrocarbyl refers to groups containing hydrogen and carbon atoms as well as

heteroatoms . Such groups may be saturated or unsaturated, branched or unbranched and may contain aromatic and/or aliphatic moieties.

Preferably, any substituents on the

phosphabicyclohydrocarbyl group carbon atoms are selected from the group consisting of alkyl groups, halogen atoms and groups of general formulae =0, =S, -OH, -OR⁴, -COR⁴, -C(0)-OR⁴, -SH, -SR⁴, -C(0)-SR⁴, -NH₂, -NHR⁴, -NRR⁵, -N0₂, -CN, -C(0)-NH₂, -C(0)-NHR⁴, -C (O) -NR⁴R⁵ and CI₃, in which R⁴ and R⁵ independently represent alkyl groups having from 1 to 4 carbon atoms, such as methyl, ethyl, n- propyl, isopropyl, n-butyl, iso-butyl and t-butyl .

Preferably, if the phosphabicyclohydrocarbyl ring is substituted it is substituted with one or more alkyl groups, preferably having from 1 to 10 carbon atoms, more preferably from 1 to 4 carbon atoms. Linear, branched or cyclic alkyl groups can be used. Suitable alkyl groups include, methyl, ethyl, propyl, iso-propyl, butyl and iso-butyl. More suitably methyl groups are used. The substituted phosphabicyclohydrocarbyl ring can be mono- or poly-substituted and is preferably di-substituted. Most preferably, if the phosphabicyclohydrocarbyl ring is substituted, it is substituted with two methyl groups.

In one preferred embodiment of the present invention, the phosphabicyclohydrocarbyl group is unsubstituted .

Further, preferably, the organophosphine ligand of the present invention is of Formula (II) :

Formula (II)

wherein m = 1, 2 or 3 and n = 1, 2 or 3, with the proviso that m + n is less than or equal to 4, o = 1, 2, 3 or 4, and wherein Rl and R2 are each independently selected from the group consisting of hydrocarbyl and

heterohydrocarbyl groups, or the phosphorus atom of the P=0 group together with Rl and R2 form a cyclic

heterohydrocarbyl group.

Preferably, Rl and R2 are each a hydrocarbyl group. Further, preferably, Rl and R2 are the same hydrocarbyl group. Further, preferably, hydrocarbyl groups for Rl and R2 are selected from the group consisting of alkyl groups and aromatic groups. Suitable alkyl groups for Rl and R2 include alkyl groups containing in the range of from 1 to 20 carbon atoms, preferably 1 to 15 carbon atoms, more preferably 5 to 15 carbon atoms, most preferably 8 to 12 carbon atoms. In particular, Rl and R2 may both be n- hexyl . A suitable aromatic group for Rl and R2 is phenyl. In particular, Rl and R2 may both be phenyl.

Substituents on the alkyl and aromatic (including phenyl) groups, if present, may include heteroatoms and heterohydrocarbyl moieties. Preferably, substituents are selected from the group consisting of halogen atoms and groups of general formulae =0, =S, -OH, -OR⁴, -COR⁴, - C(0)-OR⁴, -SH, -SR⁴, -C(0)-SR⁴, -NH₂, -NHR , -NRR⁵, -N0₂,

-CN, -C(0)-NH₂, -C(0)-NHR⁴, -C(0)-NRR⁵ and CI₃, in which R⁴ and R⁵ independently represent alkyl groups having from 1 to 4 carbon atoms, such as methyl, ethyl, n- propyl, isopropyl, n-butyl, iso-butyl and t-butyl .

Alternatively, in the ligand of Formula (II), the phosphorus atom of the P=0 group together with Rl and R2 form a cyclic heterohydrocarbyl group. Said cyclic heterohydrocarbyl group may contain one ring or more than one ring. The ring or each of the rings may contain 4 to 9, preferably 5 to 7 ring atoms. Preferably, the cyclic group will be bicyclic, i.e. it will contain two rings. The ring atoms are comprised of phosphorus and carbon and, optionally, one or more of oxygen, nitrogen and sulfur. If chemically possible, any carbon or nitrogen atom in the ring may be substituted with a substituent selected from the group consisting of alkyl groups, halogen atoms and groups of general formulae =0, =S, -OH, -OR⁴, -COR⁴, -C(0)-OR⁴, -SH, -SR⁴, -C(0)-SR⁴, -NH₂, -NHR , -NR⁴R⁵, -NO₂, -CN, -C(0)-NH₂, -C (0) -NHR⁴, -C (0) -NR⁴R⁵ and CI₃, in which R⁴ and R⁵ independently represent alkyl groups having from 1 to 4 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, iso-butyl and t- butyl .

Still further, preferably, the organophosphine ligand of the present invention comprises two

phosphabicyclohydrocarbyl groups and is of Formula (III) :

Formula (III)

wherein m = 1, 2 or 3 and n = 1, 2 or 3, with the proviso that m + n < 4, and o = 1, 2, 3 or 4. Preferably, either m = 3 and n = 1 or m = 2 and n = 2, and preferably o = 1 or 2, more preferably o = 1. It is also envisaged that the ligand of the present invention comprises a mixture of a ligand of Formula (III) wherein m = 3 and n = 1 and a ligand of Formula (III) wherein m = 2 and n = 2, wherein for both said ligands preferably o = 1 or 2, more preferably o = 1.

The embodiments and preferences as described above with respect to the phosphabicyclohydrocarbyl group in the ligand of Formula (I) also apply to the

phosphabicyclohydrocarbyl group (s) in the above ligands of Formulas (II) and (III) .

In the catalyst and the process of the present invention, suitable Group VIII metals (as used herein the terminology 'Group VIII' is according to 'previous IUPAC form' , the Periodic Table of the Elements as published in R C Weast (Ed, ) "Handbook of Chemistry and Physics", 54^th edition, CRC Press, inside cover) are cobalt, rhodium, ruthenium, nickel, palladium and platinum. Preferably, the Group VIII metal is cobalt. _ g _

Cobalt hydroformylation catalysts according to the present invention can be prepared by a diversity of methods well known to those skilled in the art as disclosed in US3369050, US3501515, US3448157, US3420898 and US3440291, which are all herein incorporated by reference. A convenient method is to combine a cobalt salt, organic or inorganic, with the desired phosphine ligand, for example, in liquid phase followed by

reduction and carbonylation . Suitable cobalt salts comprise, for example, cobalt carboxylates such as acetates, octanoates, etc. as well as cobalt salts of mineral acids such as chlorides, fluoride, sulfates, sulfonates, etc. as well as mixtures of one or more of these cobalt salts. The valence state of the cobalt may be reduced and the cobalt-containing complex formed by heating the solution in an atmosphere of hydrogen and carbon monoxide. The reduction may be performed prior to the use of the organophosphine modified cobalt

hydroformylation catalysts or it may be accomplished in- situ with the hydroformylation process in the

hydroformylation environment. Alternatively, the organophosphine modified cobalt hydroformylation

catalysts can be prepared from a carbon monoxide complex of cobalt. For example, it is possible to start with dicobalt octacarbonyl and, by mixing this substance with a suitable phosphine ligand, the ligand replaces one or more of the carbon monoxide molecules, producing an organophosphine modified cobalt hydroformylation

catalyst; the active catalyst compound is typically formed under process conditions.

The ethylenically unsaturated compound, used as starting material in the process of the present

invention, is preferably an ethylenically unsaturated compound having from 2 to 4 0 carbon atoms per molecule, or a mixture thereof. Preferred are compounds having from 2 to 30 carbon atoms, or mixtures thereof. The advantages of the process according to the invention are further especially pronounced for larger ethylenically

unsaturated compounds comprising at least 4 carbon atoms, and preferably at least 6 carbon atoms. More preferably such a large ethylenically unsaturated compound comprises 8 or more carbon atoms, preferably from 8 to 25 and more preferably from 8 to 1 8 carbon atoms. The ethylenically unsaturated compound can further be a straight carbon chain or can be branched. Suitable ethylenically

unsaturated compounds hence include substituted

compounds. Preferably such substituents are alkyl groups, preferably alkyl groups comprising from 1 to 6 , more preferably from 1 to 4 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, iso-butyl and tert- butyl . Examples of suitable ethylenically unsaturated compounds include mono-alkenes , such as ethene, propene, butene, pentene, 1-hexene, internal hexenes, 1-heptene, internal heptenes, 1-octene, internal octenes, 1-nonene or internal nonenes, 1-decene or internal decenes, undecenes, methyl-branched undecenes, dodecenes, methyl- branched dodecenes, methyl-substituted or unsubstituted Ci3, Ci4, Ci5, Ci6, Ci7, Cie , C19 or C₂o-olefins and mixtures of those. Another suitable example of a branched

ethylenically unsaturated compound is a vinylidene compound of formula CH2=CRi ( R₂ ) wherein Ri and R₂ may be the same or different, and are alkyl groups, containing preferably 1 to 30 carbon atoms, more preferably 3 to 2 0 carbon atoms, even more preferably 5 to 15 carbon atoms, and most preferably 8 to 1 0 carbon atoms, which alkyl groups can be straight carbon chains or can be branched. The process is further suitable for the

hydroformylation of mono-alkenes in the presence of dienes .

The ethylenically unsaturated compound can further be an ethylenically unsaturated compound comprising

functional groups or heteroatoms , such as nitrogen, sulphur or oxide. Examples include unsaturated carboxylic acids, esters of such acids or alkene nitriles. Suitable ethylenically unsaturated compounds comprising functional groups or heteroatoms include, for example, pentene nitriles and methyl-pentenoates .

Preferably, however, the ethylenically unsaturated compound does not comprise any functional groups or heteroatoms and is an olefin comprising only carbon atoms.

In the process of the invention, the unsaturated starting material and the formed product may act as reaction diluent. Hence, the use of a separate solvent is not necessary. Conveniently, however, the hydro- formylation reaction may be carried out in the additional presence of a solvent which is inert, or which does not interfere to any substantial degree with the desired hydroformylation reaction under the conditions employed. Saturated liquid hydrocarbons, for example, may be used as solvent in the process, as well as alcohols, ethers, acetonitrile, sulfolane, and the like. Alternatively, a part of an alcoholic reaction product may, if desired, be recycled to the reaction zones to function as solvent and/or diluent and/or suspending medium for the catalyst, the catalyst components, and the like.

Admixtures of promoters and/or stabilizers and the like may also be included in the process of the present invention. Thus, minor amounts of phenolic stabilizers such as hydroquinone and/or alkaline agents such as hydroxides of alkali metals, for example NaOH and KOH, may be added into the process.

The quantity in which the catalyst system is used, is not critical and may vary within wide limits. Usually amounts in the range of 1CT⁸ to 1CT¹, preferably in the range of 1CT⁷ to 1CT² mole atom of Group VIII 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

Group VIII metal from 0.1 to 10, preferably

from 0.5 to 6, and more preferably from 0.5 to 3 moles of organophosphine are used

Carbon monoxide partial pressures in the range of from 1 to 65 bar are preferred. In the process according to the present invention, the carbon monoxide can be used in its pure form or diluted with an inert gas such as nitrogen, carbon dioxide or noble gases such as argon.

For hydroformylation the co-reactant can be molecular hydrogen, or more generally a hydride source. The carbon monoxide and hydrogen are preferably supplied in a molar ratio of hydrogen to carbon monoxide within the range of 10:1 to 1:5, preferably 6:1 to 1:3. The molar ratio of hydrogen to carbon monoxide can influence the type of product prepared. When the desired product is an alkanol, an excess of hydrogen is needed to enable the

hydrogenation of the originally formed aldehyde or ketone. Therefore, if the desired product is an alkanol, preferably a molar ratio of hydrogen to carbon monoxide within the range of 4:1 to 1.3:1 is used.

The process of the present invention may be carried out over a wide range of temperatures. Suitable

temperatures for the reaction environment are in the range of from 130 to 220 °C, preferably in the range of from 140 to 210 °C, more preferably in the range of from 150 to 205 °C.

The process of the present invention may be carried out at various pressures. Consequently, hydroformylation in accordance with the process of the present invention may typically be carried out at pressures below 8 x 10⁶ Pa, to as low as 1 x 10⁵ Pa. The process of the present invention is, however, not limited in its applicability to the lower pressures. Pressures in the broad range of from 1 x 10⁵ Pa up to about 2 x 10⁷ Pa, and in some cases up to about 2 x 10⁸ Pa or higher, may be employed.

Typically, the specific pressure used will be governed to some extent by the specific charge and catalyst employed. In general, pressures in the range of from about 2 x 10⁶

Pa to 10 x 10⁶ Pa and particularly in the range of from about 2.7 x 10⁶ Pa to about 9 x 10⁶ Pa are preferred.

The invention is further illustrated by the following Examples .

Exam les

1. Ligand preparation

The following ligands were prepared, which were subsequently tested in olefin hydroformylation in the following below-mentioned Examples:

Example 4: phobane-CH₂-phobane oxide

Example 5: phobane-CH₂-P (=0) ( (CH₂) ₅CH₃) ₂

Example 6: phobane-CH₂-P (=0) Ph₂

Preparation of phobane-CH₂-phobane oxide

The reactions carried out in order to prepare below Compound C (phobane-CH₂-phobane oxide) , having above- mentioned Formula (III) wherein m+n=4 and o=l, which is a ligand in accordance with the present invention, are schematically shown below.

A B C

Compound A (20.3 g, 0.14 mole) was dissolved in THF (20 cm³) and the solution was then cooled to 0 °C . A THF solution of 1M (1 molar) BH₃ · THF (157 cm³, 0.16 mole) was added dropwise over 1 hour and the reaction mixture was stirred for a further 1 hour. Solvent was removed under reduced pressure to give a colourless oil. The oil was then dissolved in THF (100 cm³) and cooled to 0 °C . 1.6M nBuLi (107 cm³, 0.17 mole) was added dropwise over 2 hours and then the reaction mixture was cooled to -78 °C . Then CH₂C1₂ (10.1 cm³, 0.16 mole) was slowly added

dropwise over 30 minutes. The reaction mixture was stirred in a dry ice bath and allowed to reach room temperature overnight. The colourless precipitate was filtered off and dried under reduced pressure (16.8 g, 0.052 mole) . The precipitate was then redissolved in pyrrolidine (62 cm³) and was heated to reflux at 90 °C for 24 hours. Solvent was removed under reduced pressure to give a white paste, which was extracted with hexane

(140 cm³) and N₂-saturated water (100 cm³) . The aqueous layer was washed with hexane (2 times 80 cm³) . The combined hexane layers were dried over MgS0₄, filtered and concentrated under reduced pressure to give a white solid, that is to say above-mentioned Compound B (12.1 g,

0.041 mole) .

Compound B (0.49 g, 1.64 mmole) was dissolved in diethyl ether (10 cm³) and 2M HC1 in diethyl ether (1.10 cm³, 2.13 mole) was added over 2 minutes to give a white precipitate immediately. The solid was filtered off, washed with diethyl ether (5 cm³) and dried under reduced pressure. The precipitate was dissolved in methanol (10 cm³) and cooled to 0 °C and stirred vigorously while H₂O₂ (30 wt.%, 0.16 cm³, 1.64 mmole) was added. Solvent was removed under reduced pressure to give a white

precipitate (0.452 g, 1.30 mmole) . The precipitate was suspended in diethyl ether (15 cm³), and NEt₃ (0.23 cm³, 1.64 mmole) was added. The reaction mixture was stirred for 4 hours after which the supernatant was filtered. The precipitate was washed with hexane (7 times 20 cm³) . The combined washings were concentrated under reduced

pressure and sublimed under reduced pressure to give Compound C as a colourless solid (0.25 g, 0.8 mmole) . Preparation of phobane-CH₂-P (=0) ( (CH₂)5CH₃)2 and phobane- CH₂-P (=0) Ph₂

Two other ligands in accordance with the present invention were prepared, having above-mentioned Formula (ID :

Formula (II)

wherein m+n=4, o=l, and Rl and R2 were either both n- hexyl or both phenyl. These 2 ligands were phobane-CH₂- P(=0) ( (CH₂)₅CH₃)2 and phobane-CH₂-P (=0) Ph₂, respectively. These 2 ligands were prepared in the following way, in both cases as mixtures of the symmetric ("sym") isomer (n=m=2) and the asymmetric ("asym") isomer (n=3, m=l) isomer. The below-mentioned compound "PhobPCl" is of the following formula:

wherein n+m=4, and n=m=2 (sym isomer) and n=3, m=l (asym isomer) .

Preparation of sym- and 35ym-phobane-CH₂-P (=0) ( (CH2)5C¾)2 mixture

To a solution of 2M LDA in THF (58.0 cm³, 0.116 mol) cooled to -78 °C, was added a solution of

methyldihexylphosphine oxide (13.5 g, 0.058 mol) in THF

(180 cm³) over 4 min. The brown reaction mixture was stirred for a further 10 min during which time the temperature was kept below -65 °C . A 1.6:1 solution of sym- and asym-PhobPCl mixture (8.64 g, 0.049 mol) in THF

(120 cm³) was slowly added over 90 min. The brown

reaction mixture was stirred for 16 h and the temperature was slowly raised to room temperature over 16 h. The solvent was removed under reduced pressure to give a brown oil and then redissolved in acetonitrile (400 cm³) . After 48 h, the solvent was removed under reduced

pressure to give a yellow foam-like solid. The

precipitate was then dissolved in diethyl ether (120 cm³) and neutralised with a deoxygenated solution of aqueous ammonium chloride. The organic phase was separated and the aqueous phase was washed with diethyl ether (3x 100 cm³) . The combined organic phases were dried over MgS0₄, filtered and concentrated under reduced pressure to give a yellow oil of sym- and asym- phobane-C¾- P (=0) ( (CH₂) ₅CH3) 2 mixture (26.0 g, 0.035 mol, 90% pure by ³¹P NMR) .

Preparation of sym- and 35ym-phobane-CH₂-P (=0) Ph₂ mixture

To a solution of 2M LDA in THF (48.9 cm³, 0.098 mol) cooled to -78 °C, was added a solution of

methyldiphenylphosphine oxide (10.6 g, 0.049 mol) in THF (125 cm³) over 6 min. The yellow reaction mixture was stirred for further 10 min during which time the temperature was kept below -65 °C . A 1.6:1 solution of sym- and asym-PhobPCl mixture (8.64 g, 0.049 mol) in THF (100 cm³) was slowly added over 30 min. The brown

reaction mixture was stirred and allowed to warm to room temperature over 16 h. The solvent was then removed under reduced pressure to give a brown oil which was then redissolved in acetonitrile (120 cm³) . After 48 h, the solvent was removed under reduced pressure to give a yellow precipitate. The precipitate was then dissolved in diethyl ether (80 cm³) and neutralised with a

deoxygenated solution of aqueous ammonium chloride. The organic phase was separated and the aqueous phase was washed with diethyl ether (3x 60 cm³) . The combined organic phases were dried over MgSC^, filtered and concentrated under reduced pressure to give a yellow oil of sym- and asym-phobane-CH2-P (=0) Ρ]¾ mixture (13.0 g, 0.018 mol, 84% pure by ³¹P NMR) .

2. Olefin hydroformylation

Comparative Examples 1, 2 and 3 and Example 4 were carried out as follows. An autoclave was filled with solvent ( 2-ethylhexanol ) , a mixture of Cll and C12 olefins and KOH (K:Co = 0.5) . The mixture was heated to 190°C and a pressure of 50 bars syngas (at a ¾ : CO ratio of 1.8:1) was applied. A catalyst solution containing Co ( 2-ethylhexanoate ) 2 and a phosphine ligand (at a ratio of P : Co of 1.5:1) in 2-ethylhexanol, was injected into the autoclave. The cobalt concentration in the reaction mixture was 0.11 wt . % . The reaction was followed for 6 hours and samples were taken at regular intervals. The results obtained are shown in Table 1.

Example 5 was carried out as follows. An autoclave was filled with solvent (2-ethylhexanol), a catalyst solution containing cobaltoctacarbonyl, 2-ethylhexanoic acid (acid:Co = 0.15) and a phosphine ligand (at a ratio of P:Co of 1.3:1) in toluene and KOH (K:Co = 0.5). The mixture was heated to 190°C and a pressure of 50 bars syngas (at a H₂ : CO ratio of 1.8:1) was applied. A mixture of Cll and C12 olefins was injected into the autoclave.

The cobalt concentration in the reaction mixture was 0.11 wt . % . The reaction was followed for 6 hours and samples were taken at regular intervals. The results obtained are shown in Table 1.

Example 6 was carried out in the same way as Example

5, but with a reaction temperature of 200°C, a syngas pressure of 70 bar, P : Co = 1.5 and K:Co = 0.7. The results obtained are shown in Table 1.

Table 1

measured after 6 hours

- comparative example

The ligands used in Examples 4, 5 and 6 are in accordance with the present invention. The ligands used in Comparative Examples 1, 2 and 3 comprised Compounds 1, 2 and 3, respectively, as shown below, which compounds are also disclosed in above-mentioned US20100036171.

1 2 3 As can be seen from comparing the results on paraffin make and on "k" in the 2nd and 4th columns in Table 1, respectively, the ligands of the present invention

(Examples 4, 5 and 6) perform surprisingly far better in that the amount of paraffin by-products formed in the hydroformylation process is reduced significantly, and at the same time the activity or reaction rate of the hydroformylation reaction is considerably improved.

In Comparative Example 7, the compound phobane- CH₂CH₂-phobane (commercially available at Cytec) was used as a ligand. Said compound differs from the ligand used in Example 4 (Compound C) in that there is no =0 moiety on one of the P atoms. Comparative Example 7 was carried out as follows. A 300 ml autoclave was charged with 100 g of isomerised dodecene, cobalt ( 2-ethylhexanoate ) 2 and a potassium hydroxide solution. The cobalt concentration was 0.2 wt.%, K:Co = 0.85 and ligand: Co = 1.5. The reaction mixture was heated to 200 °C for 24 hours at a constant pressure of 76 bar of ¾ : CO = 2. After 24 hours, the product was analysed. The conversion of dodecene was found to be 0%. This result from Comparative Example 7 demonstrates the importance of the =0 moiety in the ligands of the present invention which showed a

relatively high activity or reaction rate as discussed above .

Claims

C L A I M S

1. An organophosphine ligand comprising a

2. The organophosphine ligand of claim 1 wherein the phosphorus oxide group or sulfur oxide group is at the beta-, gamma-, delta- or epsilon-position of the

heterohydrocarbyl moiety.

3. The organophosphine ligand of claim 2 wherein the phosphorus oxide group or sulfur oxide group is at the beta-position of the heterohydrocarbyl moiety.

4. The organophosphine ligand of any one of the

preceding claims wherein the organophosphine ligand is of Formula ( I ) :

Formula (I)

wherein m = 1, 2 or 3 and n = 1, 2 or 3, with the proviso that m + n is less than or equal to 4, and R represents the remainder of the ligand.

5. The organophosphine ligand of claim 4 wherein m = 3 and n = 1 or wherein m = 2 and n = 2.

6. The organophosphine ligand of claim 4 or 5 wherein the organophosphine ligand is of Formula (II) :

Formula (II)

heterohydrocarbyl group.

7. The organophosphine ligand of claim 6 wherein the organophosphine ligand is of Formula (III) :

Formula (III)

wherein m = 1, 2 or 3 and n = 1, 2 or 3, with the proviso that m + n 4, and o = 1, 2, 3 or 4.

8. The organophosphine ligand of claim 6 or 7 wherein m = 3 and n = 1 or wherein m = 2 and n = 2, and wherein o = 1.

9. A catalytic composition for the hydroformylation of an ethylenically unsaturated compound, said catalytic composition comprising

i) a source of Group VIII metal cations; and

ii) the organophosphine ligand of any one of claims 1-8.

10. The catalytic composition of claim 9 wherein the group VIII metal is cobalt.

11. A process for the hydroformylation of an

ethylenically unsaturated compound, said process

comprising contacting the ethylenically unsaturated compound with carbon monoxide and hydrogen in the presence of the catalytic composition of claim 9 or 10.

12. The process of claim 11 wherein the ethylenically unsaturated compound is a mono-alkene.