ZA200504750B - Tetramerization of olefins - Google Patents

Description

TETRAMERIZATION OF OLEFINS

Field of the invention:

This invention relates to the oligomerisation of ethylene. More particularly, the invention relates to a tetramerisation process, a catalyst system for tetramerisation of olefins and the identification and use of ligands for a catalyst system for tetramerisation of olefins.

Background of the invention

This invention defines a process and catalyst system, that facilitates the production of 1- octene in high selectivity, while avoiding the co-production of significant quantities of butenes, other octene isomers, specific higher oligomers and polyethylene. The catalyst system can also be used for the tetramerisation of other olefins, especially a~olefins.

Despite the well known value of 1-octene, the art does not teach a commercially successful process for the tetramerisation of ethylene to produce 1-octene selectively.

Conventional ethylene oligomerisation technologies produce a range of a olefins following either a Schulz-Flory or Poisson product distribution. By definition, these mathematical distributions limit the mass % of the tetramer that can be formed and make a distribution of products. In this regard, it is known from the prior art (US patent 6,184,428) that a nickel catalyst comprising a chelating ligand, preferably 2-diphenyl phosphino benzoic acid (DPPBA), a nickel compound, preferably NiCl,.6H,O, and a catalyst activator, preferably sodium tetraphenylborate, catalyse the oligomerisation of ethylene to yield a mixture of linear olefins. The selectivity towards linear C8 a-olefins is claimed to be 19%. Similarly the Shell Higher Olefins Process (SHOP process, US patents 3,676,523 and 3,635,937) using a similar catalyst system is reported to typically yield 11 mass % 1-octene in its product mixture (Chem Systems PERP reports 90-1, 93- 6 and 94/95812).

Ziegler-type technologies based on trialkylaluminium catalysts, independently developed by Gulf Oil Chemicals Company (Chevron, e.g. DE patent 1,443,927) and Ethyl

Corporation (BP/Amoco, e.g. US patent 3,906,053), are also commercially used to oligomerise ethylene to mixtures of olefins that reportedly contain 13-25 mass % 1- octene (Chem Systems PERP reports 90-1, 93-6, and 94/95S12).

The prior art also teaches that chromium-based catalysts containing heteroatomic ligands with both phosphorus and nitrogen heteroatoms selectively catalyse the trimerisation of ethylene to 1-hexene. Examples of such heteroatomic ligands for ethylene trimerisation include bis(2-diethylphosphino-ethyl) amine (WO 03/053891, hereby fully incorporated herein by means of reference) as well as (o- methoxyphenyi),PN(methyl)P(o-methoxyphenyl), (WO 02/04119, hereby fully - incorporated herein by means of reference). Both these catalyst systems and processes are very specific for the production of 1-hexene and only yield 1-octene as an impurity (typically less than 3 mass % of the product mixture as disclosed by WO 02/04119). The coordinating phosphorus heteroatoms in (o-methoxyphenyl),PN(methyl)P(o- methoxyphenyl), (WO 02/04119) are spaced apart by one nitrogen atom. It is believed that the nitrogen atom does not coordinate, at least in the absence of an activator, with the chromium and that without any further electron donating atoms on the ligand that it is a bidentate system. Furthermore it is argued that the polar, or electron donating substituents in the ortho-position of the phenyl groups help form a tridentate system, which is generally believed to enhance selectivity towards 1-hexene formation as reiterated by the inventor of WO 02/04119 in Chem. Commun., 2002, 858-859 by stating “This has led us to hypothesise that the potential for ortho-methoxy groups to act as pendent donors and increase the coordinative saturation of the chromium centre is an important factor.” To support their hypothesis, the authors of Chem. Commun., 2002, 858-859 showed that the use of (p-methoxyphenyi),PN(methyl)P(p-methoxyphenyl),, a compound without any such otho-polar substituents on at least one of R!, R?, R® and R*, as a ligand under catalytic conditions resulted in no catalytic activity towards a-olefins.

WO 02/04119 (Example 16) teaches the production of octenes using a trimerisation of olefins process and catalyst system. In this instance, 1-butene was co-trimerised with two ethylene molecules to give 25% octenes. However, the nature of these octenes was not disclosed and the applicant believes that they consist of a mixture of linear and branched octenes.

The prior art teaches that high 1-octene selectivities cannot be achieved since expansion of the generally accepted seven-membered metallacycle reaction intermediate for ethylene trimerisation (Chem. Commun., 1989, 674) to a nine- membered metallacyle is unlikely to occur (Organometallics, 2003, 22, 2564; Angew.

Chem. Int. Ed., 2003, 42 (7), 808). It is argued that the nine-membered ring is the least favoured medium sized ring and should thus be disfavoured relative to the seven- membered ring (Organometallics, 2003, 22, 2564). In addition, it is also stated by the same authors that, “if a nine-membered ring formed, it would be more likely to grow to an eleven- or thirteen-membered ring...In other words, one would never expect much octene, but formation of some (linear) decene or dodecene would be more reasonable.”

Despite the teaching of the opposite, the applicant has now found a process for selectively producing a tetramerised olefin. The applicant has further found that chromium-based catalysts containing mixed heteroatomic ligands with both nitrogen and phosphorus heteroatoms, with polar substituents on the hydrocarbyl or heterohydrocarbyl groups on the phosphorous atoms, can be used to selectively tetramerise ethylene to 1-octene often in excess of 60 mass% selectivity. This high 1- octene selectivity cannot be achieved via conventional one-step ethylene oligomerisation or trimerisation technologies which at most yield 25 mass% 1-octene.

Summary of the invention

This invention relates to a process for selectively producing tetrameric products.

This invention specifically relates to a process for selectively producing tetrameric products such as 1-octene from olefins such as ethylene.

The invention relates to a process of selectively producing tetrametric products using a transition metal catalyst system containing a heteroatomic ligand.

According to a first aspect of the invention there is provided a process for tetramerisation of olefins wherein the product of the tetramerisation process is an olefin and makes up more than 30% of the product stream of the process.

According to a second aspect of the invention the tetramerisation process includes the step of contacting an olefinic feedstream with a catalyst system which includes a transition metal and a heteroatomic ligand and wherein the product of the tetramerisation process is an olefin and makes up more than 30% of the product stream of the process.

In this specification, % will be understood to be a mass %.

The term “tetramerisation” generally refers to the reaction of four, and preferably four identical, olefinic monomer units to yield a linear and/or branched olefin.

By heteroatomic is meant a ligand that contains at least two heteroatoms, which can be the same or different, where the heteroatoms may be selected from phosphorus, arsenic, antimony, sulphur, oxygen, bismuth, selenium or nitrogen.

The feedstream will be understood to include an olefin to be tetramerised and can be introduced into the process according to the invention in a continuous or batch fashion.

The product stream will be understood to include a tetramer, which tetramer is produced according to the invention in a continuous or batch fashion.

The feedstream may include an a-olefin and the product stream may include at least 30%, preferably at least 35%, of a tetramerised a-olefin monomer.

The process may include a process for tetramerisation of a-olefins. Under the term o— olefins is meant all hydrocarbon compounds with terminal double bonds. This definition includes ethylene, propylene, 1-butene, isobutylene, 1-pentene, 1-hexene, 1-octene and the like.

The process may include a process for tetramerisation of a-olefins to selectively yield tetrameric a-olefin products.

The olefinic feedstream may include ethylene and the product stream may include at least 30% 1-octene. The process may be a process for tetramerisation of ethylene.

The invention allows the ligand, catalyst system and/or process conditions to be selected to give a product stream of more than 40%, 50%, or 60% a-olefins. It may be preferable, depending on the further use of the product stream, to have such high selectivities of the a-olefin.

The olefinic feedstream may include ethylene and the (Cg + Cg) : (C4 + Cy ) ratio in the product stream may be more than 2.5:1.

The olefinic feedstream may include ethylene and the Cs : Cg ratio in the product stream is more than 1.

The ethylene may be contacted with the catalyst system at a pressure of greater than 1 barg and preferably greater than 10 barg, more preferably greater than 30 barg.

The heteroatomic ligand may be described by the following general formula (R)nA-B-C(R)m where A and C are independently selected from a group which comprises phosphorus, arsenic, antimony, oxygen, bismuth, sulphur, selenium, and nitrogen, and B is a linking group between A and C, and R is independently selected from any homo or heterohydrocarbyl group of which at least one R group is substituted with a polar substituent and n and m is determined by the respective valence and oxidation state of A and C.

A and/or C may be a potential electron donor for coordination with the transition metal.

An electron donor or electron donating substituent is defined as that entity that donates electrons used in chemical, including dative covalent, bond formation.

The heteroatomic ligand may be described by the following general formula (R' XR?)A-B-

C(R*)(R*) where A and C are independently selected from a group which comprises phosphorus, arsenic, antimony, bismuth and nitrogen and B is a linking group between A and C, and R', R% R® and R* are independently selected from non-aromatic and aromatic, including heteroaromatic, groups of which at least one of R', R?, R® and R* is substituted with a polar substituent.

In some embodiments of the process aspect of the invention, up to four of R', R?, R? and

R* may have substituents on the atom adjacent to the atom bound to A or C.

In addition to at least one of R', R?, R® and R* being substituted with a polar substituent, each of R', R? R® and R* may be aromatic, including heteroaromatic, but preferably not all of R", R?, R® and R*, if they all are aromatic, are substituted by any substituent on an atom adjacent to the atom bound to A or C.

In addition to at least one of R’, R?, R® and R* being substituted with a polar substituent, not more than two of R', R?, R® and R*, if they are aromatic, may have substituents on the atom adjacent to the atom bound to A or C.

Any polar substituents on R', R?, R® and R*, if they are aromatic, may preferably not be on the atom adjacent to the atom bound to A or C.

At least one of R', R?, R® and R*, if aromatic, may be substituted with a polar substituent on the 2™ or further atom from the atom bound to A or C.

Any polar substituent on one or more of R', R%, R® and R* may be electron donating.

Polar is defined by IUPAC as an entity with a permanent electric dipole moment. Polar substituents include methoxy, ethoxy, isopropoxy, C;-Cy alkoxy, phenoxy, pentafluorophenoxy, trimethylsiloxy, dimethylamino, methylsulfanyl, tosyl, methoxymethy, methyithiomethyl, 1,3-oxazolyl, methomethoxy, hydroxyl, amino, phosphino, arsino, stibino, sulphate, nitro and the like.

Any of the groups R', R?, R® and R* may independently be linked to one or more of each other or to the linking group B to form a cyclic structure together with A and C, A and B orBandC.

R’, R? R® and R* may be independently selected from a group comprising a benzyl, phenyl, tolyl, xylyl, mesityl, biphenyl, naphthyl, anthracenyl, methoxy, ethoxy, phenoxy, tolyloxy, dimethylamino, diethylamino, methylethylamino, thiophenyl, pyridyl, thioethyl, thiophenoxy, trimethylsilyl, dimethylhydrazyl, methyl, ethyl, ethenyl, propyl, butyl, propenyl, propynyl, cyclopentyl, cyclohexyl, ferrocenyl and tetrahydrofuranyl group.

Preferably, R', R?, R? and R* may independently be selected from a group comprising a phenyl, tolyl, biphenyl, naphthyl, thiophenyl and ethyl group.

A and/or C may be independently oxidised by S, Se, N or O, where the valence of A and/or C allows for such oxidation.

A and C may be independently phosphorus or phosphorus oxidised by S or Se or N or oO.

B may be selected from any one of a group comprising: organic linking groups comprising a hydrocarbyl, substituted hydrocarbyl, heterohydrocarbyl and a substituted heterohydrocarbyl; inorganic linking groups comprising single atom links; ionic links; and a group comprising methylene, dimethylmethylene, 1,2-ethane, 1,2-phenylene, 1,2- propane, 1,2-catechol, 1,2-dimethylhydrazine, -B(R%)-, -Si(R%)-, -P(R®)- and -N(R%)- where R® is hydrogen, a hydrocarbyl or substituted hydrocarbyl, a substituted heteroatom or a halogen. Preferably, B may be -N(R°)- and R® is a hydrocarbyl or a substituted hydrocarbyl group. R® may be hydrogen or may be selected from the groups consisting of alkyl, substituted alkyl, aryl, substituted aryl, aryloxy, substituted aryloxy, halogen, nitro, alkoxycarbonyl, carbonyloxy, alkoxy, aminocarbonyl, carbonylamino, dialkylamino, silyl groups or derivatives thereof, and aryl substituted with any of these substituents. Preferably R® may be an isopropyl, a 1-cyclohexylethyl, a 2- methylcyclohexyl or a 2-octyl group.

B may be selected to be a single atom spacer. A single atom linking spacer is defined as a substituted or non-substituted atom that is bound directly to A and C.

The ligand may also contain multiple (R),A-B-C(R)m, units. Non limiting examples of such ligands include dendrimeric ligands as well as ligands where the individual units are coupled either via one or more of the R groups or via the linking group B . More specific, but non limiting, examples of such ligands may include 1,2-di-(N(P(4- methoxyphenyl).).)-benzene, 1,4-di-(N(P(4-methoxyphenyl),).)-benzene,

N(CH,CH,N(P(4-methoxyphenyl),).); and 1,4-di~(P(4-methoxyphenyl)N(methyl)P(4- methoxyphenyl).)-benzene.

The ligands can be prepared using procedures known to one skilled in the art and procedures disclosed in published literature. Examples of ligands are: (3- methoxyphenyl),PN(methyl)P(3-methoxyphenyl),, ~~ (4-methoxyphenyl!),PN(methyl)P(4- methoxyphenyl),, (3-methoxyphenyl),PN(isopropyl)P(3-methoxyphenyl),,(4- methoxyphenyl),PN(isopropyl)P(4-methoxyphenyl),, (4-methoxyphenyl),PN(2- ethylhexyl)P(4-methoxyphenyl)s, (3-methoxyphenyl)(phenyl)PN(methyl)P(phenyl), and (4-methoxyphenyl)(phenyl)PN(methyl)P(phenyl),, (3- methoxyphenyl)(phenyl)PN(methyl)P(3-methoxyphenyl)(phenyl), (4- methoxyphenyl)(phenyl)PN(methyl)P(4-methoxyphenyl)(phenyl), (3- methoxyphenyl),PN(methyl)P(phenyl), and (4-methoxyphenyl),PN(methyl)P(phenyl),, (4- methoxypheny!),PN(1-cyclohexylethyl)P(4-methoxyphenyl),, (4-methoxyphenyl),PN(2- methylcyclohexyl)P(4-methoxyphenyl),, (4-methoxyphenyl),PN(decyl)P(4- methoxyphenyl),, (4-methoxyphenyl),PN(pentyl)P(4-methoxyphenyt),, (4- methoxyphenyl),PN(benzyl)P(4-methoxyphenyl),, (4-methoxyphenyl),PN(phenyl)P(4- methoxyphenyl),, (4-fluorophenyl),PN(methyl)P(4-flucrophenyt),, (2- fluorophenyl),PN(methyl)P(2-fluorophenyl),, (4-dimethylamino-phenyl),PN(methyl)P(4- dimethylamino-phenyl),, (4-methoxyphenyl),PN(allyl)P(4-methoxyphenyl),, (phenyl):PN(isopropyl)P(2-methoxyphenyl)s, (4-(4-methoxyphenyl)- phenyl).PN(isopropyl)P(4-(4-methoxyphenyl)-phenyl), and (4- methoxyphenyl)(phenyl)PN(isopropyl)P(phenyl),.

The catalyst system may include an activator and the process may include the step of combining in any order a heteroatomic ligand with a transition metal compound and an activator.

The process may include the step of generating a heteroatomic coordination complex in situ from a transition metal compound and a heteroatomic ligand. The process may include the step of adding a pre-formed coordination complex, prepared using a heteroatomic ligand and a transition metal compound, to a reaction mixture, or the step of adding separately to the reactor, a heteroatomic ligand and a transition metal compound such that a heteroatomic coordination complex of a transition metal is generated in situ. By generating a heteroatomic coordination complex in situ is meant that the complex is generated in the medium in which catalysis takes place. Typically, the heteroatomic coordination complex is generated in situ. Typically, the transition metal compound, and heteroatomic ligand are combined (both in situ and ex situ) to provide metal/ligand ratios from about 0.01:100 to 10 000:1, and preferably, from about 0.1:1 to 10:1.

The transition metal may be selected from any one of a group comprising chromium, molybdenum, tungsten, titanium, tantalum, vanadium and zirconium, preferably chromium.

The transition metal compound which, upon mixing with the heteroatomic ligand and an activator, catalyses ethylene tetramerisation in accordance with the invention, may be a simple inorganic or organic salt, a co-ordination or organometallic complex and may be selected from any one of a group comprising chromium trichloride tris-tetrahydrofuran complex, (benzene)tricarbonyl chromium, chromium (lll) octanoate, chromium hexacarbonyl, chromium (lll) acetylacetonoate and chromium (Ill) 2-ethylhexanoate. The preferred transition metal compounds include chromium (Ill) acetylacetonoate and chromium (lif) 2-ethylhexanoate.

The heteroatomic ligand can be modified to be attached to a polymer chain so that the resulting heteroatomic coordination complex of the transition metal is soluble at elevated temperatures, but becomes insoluble at 25°C. This approach would enable the recovery of the complex from the reaction mixture for reuse and has been used for other catalyst as described by D.E. Bergbreiter et al., J. Am. Chem. Soc., 1987, 109, 177-179. In a similar vein these transition metal complexes can also be immobilised by binding the heteroatomic ligands for example to silica, silica gel, polysiloxane, alumina backbone or the like as demonstrated, for example, by C. Yuanyin et al., Chinese J. React. Pol., 1992, 1(2), 162-159 for immobilising platinum complexes.

The activator for use in the process may in principle be any compound that generates an active catalyst when combined with the heteroatomic ligand and the transition metal compound. Mixtures of activators may also be used. Suitable compounds include organoaluminium compounds, organoboron compounds, organic salts, such as methyllithium and methylmagnesium bromide, inorganic acids and salts, such as tetrafluoroboric acid etherate, silver tetrafluoroborate, sodium hexafluoroantimonate and the like.

Suitable organoaluminium compounds include compounds of the formula AIR,;, where each R is independently a C;-Ci alkyl, an oxygen containing moiety or a halide, and compounds such as LiAlH, and the like. Examples include trimethylaluminium (TMA), triethylaluminium (TEA), tri-isobutylaluminium (TIBA), tri-n-octylaluminium, methylaluminium dichloride, ethylaluminium dichloride, dimethylaluminium chloride, diethylaluminium chloride, aluminium isopropoxide, ethylaluminiumsesquichloride, methylaluminiumsesquichloride, and aluminoxanes. Aluminoxanes are well known in the art as typically oligomeric compounds which can be prepared by the controlled addition of water to an alkylaluminium compound, for example trimethylaluminium. Such . compounds can be linear, cyclic, cages or mixtures thereof. Mixtures of different aluminoxanes may also be used in the process.

Examples of suitable organoboron compounds are boroxines, NaBH, triethylborane, tris(pentafluoropheny)borane, tributyl borate and the like.

The activator may also be or contain a compound that acts as a reducing or oxidising agent, such as sodium or zinc metal and the like, or oxygen and the like.

The activator may be selected from alkylaluminoxanes such as methylaluminoxane (MAQ) and ethylaluminoxane (EAO) as well as modified alkylaluminoxanes such as modified methylaluminoxane (MMAO). Modified methylaluminoxane (a commercial product from Akzo Nobel) contains modifier groups such as isobutyl or n-octyl groups, in addition to methyl groups.

The transition metal and the aluminoxane may be combined in proportions to provide

Al/metal ratios from about 1:1 to 10 000:1, preferably from about 1:1 to 1000:1, and more preferably from 1:1 to 300:1.

The process may include the step of adding to the catalyst system a trialkylaluminium compound in amounts of between 0.01 to 1000 mot per mol of alkylaluminoxane.

It should be noted that aluminoxanes generally also contain considerable quantities of the corresponding trialkylaluminium compounds used in their preparation. The presence

Claims (1)

1. Claims

   1. A process for tetramerisation of olefins wherein the product stream of the process contains more than 30% of the tetramer olefin.

   2. A process as claimed in Claim 1 which process includes the step of contacting an olefinic feedstrean with a catalyst system containing a transition metal compound and a heteroatomic ligand.

   3. A process as claimed in Claim 1 or Claim 2, wherein the heteroatomic ligand is described by the following general formula (R),A-B-C(R), where A and C are independently selected from a group which comprises phosphorus, arsenic, antimony, oxygen, bismuth, sulphur, selenium, and nitrogen, and B is a linking group between A and C, and the R's are the same or different and each R is independently selected from any homo or hetero hydrocarbyl group and n and m for each R is independently determined by the respective valence and oxidation state of A and C and of which at least one of the R's is substituted with a polar substituent. 4, A process as claimed in Claim 3, wherein the ligand comprises of multiples of (R)WA-B-C(R)m.

   5. A process as claimed in any one of claims 1 to 3, which process includes the step of contacting an olefinic feedstream with a catalyst system which includes a transition metal and a heteroatomic ligand and wherein the tetramer is an olefin and makes up more than 30% of the product stream of the process and wherein the heteroatomic ligand is described by the following general formula (R')}R?)A-B-C(R*NR*) where A and C are independently selected from a group which comprises phosphorus, : arsenic, antimony, bismuth, and nitrogen and B is a linking group between A and C, and R', R? R® and R* are independently selected from non-aromatic and aromatic, including : heteroaromatic, groups of which at least one of R', R%, R® and R? is substituted with a polar substituent.

   8. A process as claimed in Claim 5, wherein up to four of R', R?, R® and R* have substituents on the atom adjacent to the atom bound to A or C.

   7. A process as claimed in Claim 5 or Claim 6, wherein each of R', R?, R® and R* is aromatic, including heteroaromatic, but not all of R', R?, R® and R* are substituted by any substituent on an atom adjacent to the atom bound to A or C.

   8. A process as claimed in Claim 7, wherein not more than two of R!, R, R® and R* have substituents on the atom adjacent to the atom bound to A or C.

   9. A process as claimed in Claim 7 or Claim 8, wherein any polar substituents on R', R%, Rand R* are not on the atom adjacent to the atom bound to A or C.

   10. A process as claimed in any one of claims 5 and 7 to 9, wherein at least one of R', R% R® and R* is substituted with a polar substituent on the 2™ or further atom from the atom bound to A or C.

   11. A process as claimed in any one of claims 3 to 5 and 7 to 10, wherein any polar substituents on one or more of R', R% R® and R* are electron donating.

   12. A process as claimed in any one of claims 1 to 5 and 7 to 11, wherein the feedstream includes an a-olefin and the product stream includes at least 30% of a tetramerised a-olefin monomer.

   13. A process as claimed in any one of claims 1 to 5 and 7 to 12, wherein the olefinic feedstream includes ethylene and the product stream includes at least 30% 1-octene. ] 14. A process as claimed in any one of claims 1 to 5 and 7 to 12, wherein the olefinic feedstream includes ethylene and the product stream includes at least 40% 1-octene.

   15. A process as claimed in any one of claims 1 to 5 and 7 to 12, wherein the olefinic feedstream includes ethylene and the product stream includes at least 50% 1-octene.

   16. A process as claimed in any one of claims 1 to 5 and 7 to 12, wherein the olefinic feedstream includes ethylene and the product stream includes at least 60% 1-octene.

   17. A process as claimed in any one of claims 1 to 5 and 7 to 16, wherein the olefinic feedstream includes ethylene and wherein the (Cs + Cg) : (C4 + Co ) ratio in the product stream is more than 2.5:1.

   18. A process as claimed in any one of claims 1 to 5 and 7 to 17, wherein the olefinic feedstream includes ethylene and wherein the Cs : C; ratio in the product stream is more than 1.

   19. A process as claimed in any one of claims 12 to 18, wherein ethylene is contacted with the catalyst system at a pressure of more than 10 barg.

   20. A process as claimed in any one of claims 3 to 5 and 7 to 19, wherein A and/or C are a potential electron donor for coordination with the transition metal.

   21. A process as claimed in any one of claims 3 to 5 and 7 to 20, wherein B is selected from any one of a group comprising: organic linking groups comprising a hydrocarbyl, substituted hydrocarbyl, heterohydrocarbyl and a substituted heterohydrocarbyl; inorganic linking groups comprising single atom links; ionic links; and a group comprising methylene, dimethylmethylene, 1,2-ethane, 1,2-phenylene, 1,2- propane, 1,2-catechol, 1,2-dimethylhydrazine, -B(R%)-, -Si(R%)-, -P(R%}- and -N(R%)- where R® is hydrogen, a hydrocarbyl or substituted hydrocarbyl, a substituted heteroatom and a halogen.

   22. A process as claimed in any one of claims 3 to 5 and 7 to 21, wherein B is selected to be a single atom spacer.

   23. A process as claimed in any one of claims 3 to 5 and 7 to 22, wherein B is ’ selected to be -N(R®)-, wherein R® is hydrogen or selected from the groups consisting of alkyl, substituted alkyl, aryl, substituted aryl, aryloxy, substituted aryloxy, halogen, nitro, alkoxycarbonyl, carbonyloxy, alkoxy, aminocarbonyl, carbonylamino, dialkylamino, silyl groups or derivatives thereof, and aryl substituted with any of these substituents.

   24. A process as claimed in any one of claims 3 to 5 and 7 to 23, wherein A and/or C is independently oxidised by S, Se, N or O, where the valence of A and/or C allows for such oxidation.

   25. A process as claimed in any one of claims 3 to 5 and 7 to 24, wherein A and C is independently phosphorous or phosphorous oxidised by S or Se or N or O.

   26. A process as claimed in any one of claims 3 to 5 and 7 to 25, wherein R’, R?, R® and R* are independently selected from a group comprising a benzyl, phenyl, tolyl, xylyl, mesityl, biphenyl, naphthyl, anthracenyl, methoxy, ethoxy, phenoxy, tolyloxy, dimethylamino, diethylamino, methylethylamino, thiophenyl, pyridyl, thioethyl, thiophenoxy, trimethylsilyl, dimethylhydrazyl, methyl, ethyl, ethenyl, propyl, butyl, propenyl, propynyl, cyclopentyl, cyclohexyl, ferrocenyl and tetrahydrofuranyl group.

   27. A process as claimed in any one of claims 3 to 5 and 7 to 26, wherein R, R?, R® and R* are independently selected from a group comprising a phenyl, tolyl, biphenyl, naphthyl, thiophenyl and ethyl group.

   28. A process as claimed in any one of claims 2 to 5, 7 to 23 and 25 to 27 wherein the ligand is selected from any one of a group comprising (3- methoxyphenyl).PN(methyl)P(3-methoxyphenyl),, (4-methoxyphenyl),PN(methyl)P(4- methoxyphenyt),, (3-methoxyphenyl),PN(isopropyl)P(3-methoxyphenyl),,(4- methoxyphenyl),PN(isopropyl)P(4-methoxyphenyl)s, (4-methoxyphenyl),PN(2- ethylhexyl)P(4-methoxyphenyl);, (3-methoxyphenyl)phenyl)PN(methyl)P(phenyl), and (4-methoxyphenyl)(phenyl)PN(methyl)P(phenyl),, (3- methoxyphenyl)(phenyl)PN(methyl)P(3-methoxyphenyl)(phenyl), (4- methoxyphenyl)(phenyl)PN(methyl)P(4-methoxyphenyl)(phenyl), (3- * methoxyphenyl):PN(methyl)P(phenyl); and (4-methoxyphenyl),PN(methyl)P(phenyl),, (4- methoxyphenyl!),PN(1-cyclohexylethyl)P(4-methoxyphenyl),, (4-methoxyphenyl),PN(2- ‘ methylcyclohexyl)P(4-methoxyphenyl),, (4-methoxyphenyl),PN(decyl)P(4- methoxyphenyl),, (4-methoxyphenyl).PN(pentyl)P(4-methoxyphenyl)s,, (4- methoxyphenyl),PN(benzyl)P(4-methoxyphenyl),, (4-methoxyphenyl),PN(phenyl)P(4- methoxyphenyl),, (4-fluorophenyl),PN(methyl)P(4-fluorophenyi),, (2-

   fluorophenyl),PN(methyl)P(2-fluorophenyl),, (4-dimethylamino-phenyl),PN(methyl)P(4- ' dimethylamino-phenyl),, (4-methoxyphenyl),PN(allyl)P(4-methoxyphenyl),, (phenyl),PN(isopropyl)P(2-methoxyphenyl),, (4-(4-methoxyphenyl)- ) phenyl),PN(isopropyl)P(4-(4-methoxyphenyl)-phenyl), and (4- methoxyphenyl)(phenyl)PN(isopropyl)P(phenyl),.

   29. A process as claimed in any one of the claims 1 to 5 and 7 to 28, which process includes the step of combining in any order a heteroatomic ligand with a transition metal compound and an activator.

   30. A process as claimed in any one of claims 2 to 5 and 7 to 28, which process includes the step of adding a pre-formed coordination complex, prepared using the heteroatomic ligand and a transition metal compound, to a reaction mixture containing an activator,

   31. A process as claimed in Claim 30, which includes the step of generating a heteroatomic coordination complex in situ from a transition metal compound and a heteroatomic ligand. : 32. A process as claimed in any one of the claims 2 to 5 and 7 to 31, wherein the transition metal is selected from any one of a group comprising chromium, molybdenum, tungsten, titanium, tantalum, vanadium and zirconium.

   33. A process as claimed in any one of the claims 2 to 5 and 7 to 32, wherein the transition metal is chromium.

   34. A process as claimed in any one of claims 29 to 31, wherein the transition metal compound is selected from a group comprising of an inorganic salt, organic salt, a co- - ordination complex and organometallic complex. ‘ 35. A process as claimed in Claim 34, wherein the transition metal compound is selected from any one of a group comprising chromium trichloride tris-tetrahydrofuran complex, (benzene)tricarbonyl chromium, chromium (lll) octanoate, chromium (mn) acetylacetonoate, chromium hexacarbonyl and chromium (lil) 2-ethylhexanoate.

   36. A process as claimed in any one of claims 29 to 31 and 33 to 35, wherein the transition metal compound is selected from a complex selected from chromium (lll) ’ acetylacetonoate and chromium (lll) 2-ethylhexanoate.

   37. A process as claimed in any one of claims 29 to 36, wherein the transition metal from a transition metal compound and heteroatomic ligand are combined to provide metal/ligand ratios from about 0.01:100 to 10 000:1.

   38. A process as claimed in Claim 37, wherein the transition metal compound and heteroatomic ligand are combined to provide metal/igand ratios from about 0.1:1 to 10:1.

   39. A process as claimed in any one of claims 29 to 38, wherein the catalyst system includes an activator selected from any one of a group consisting of organoaluminium compounds, organoboron compounds, organic salts, such as methyllithium and methylmagnesium bromide, inorganic acids and salts, such as tetrafluoroboric acid ’ etherate, silver tetrafluoroborate and sodium hexafluoroantimonate.

   40. A process as claimed in any one of claims 29 to 31, wherein the activator is selected from alkylaluminoxanes. 4, A process as claimed in Claim 40, wherein the alkylaluminoxane, or mixtures thereof, is selected from group which consists of methylaluminoxane (MAO), ethylaluminoxane (EAQO) and modified alkylaluminoxanes (MMAO).

   42. A process as claimed in Claim 41, wherein the transition metal and the aluminoxane are combined in proportions to provide Al/metal ratios from about 1:1 to 10 - 000:1. : 43. A process as claimed in Claim 42, wherein the transition metal and the aluminoxane are combined in proportions to provide Al/metal ratios from about 1:1 to 1000:1.

   44. A process as claimed in Claim 43, wherein the transition metal and the aluminoxane are combined in proportions to provide Al/metal ratios from about 1:1 to 300:1.

   45. A process as claimed in any one of claims 42 to 44, which includes the step of adding to the catalyst system a trialkylaluminium compound in amounts of between 0.01 to 100 mol per mol of alkylaluminoxane.

   46. A process as claimed in any one of claims 2 to 5 and 7 to 45, which includes the step of mixing the components of the catalyst system at any temperature between -20°C and 250°C in the presence of an olefin.

   47. A process as claimed in any one of claims 2 to 5 and 7 to 46, wherein the product stream is contacted with the catalyst system at a temperature ranging between and 130 °C.

   48. A process as claimed in claims 1 to 5 and 7 to 47, wherein methylcyclopentane and methylene cyclopentane are formed as products and independently make up at least 1% of the product stream of the process.

   49. A tetramerisation catalyst system which includes a transition metal and a heteroatomic ligand described by the following general formula (R),A-B-C(R), where A and C are independently selected from a group which comprises phosphorus, arsenic, antimony, oxygen, bismuth, sulphur, selenium, and nitrogen, and B is a linking group between A and C, and the R's are the same or different and each R is independently selected from any homo or hetero hydrocarbyl group and n and m for each Ris independently determined by the respective valence and oxidation state of A and C and of which at least one of the R's is substituted with a polar substituent.

   50. A catalyst system as claimed in Claim 49, wherein the ligand comprises of multiples of (R),A-B-C(R)n-

   51. A catalyst system as claimed in Claim 49 or Claim 50 which includes a transition metal and a heteroatomic ligand described by the following general formula (R')(R*A-B-

   C(R’)(R*) where A and C are independently selected from a group which comprises ’ phosphorus, arsenic, antimony, bismuth, and nitrogen and B is a linking group between A and C, and R', R%, R® and R* are independently selected from non-aromatic and ’ aromatic, including heteroaromatic, groups of which at least one of R', R?, R® and R* is substituted with a polar substituent.

   52. A catalyst system as claimed in Claim 50 or Claim 51, wherein each of R', R?, R® and R* is aromatic, including heteroaromatic, but not all of R', R®, R® and R* are substituted by any substituent on an atom adjacent to the atom bound to A or C.

   93. A catalyst system as claimed in Claim 51 or Claim 52, wherein not more than two of R', R R® and R* have substituents on the atom adjacent to the atom bound to A or C.

   94. A catalyst system as claimed in Claim 52, wherein any polar substituents on RY, R? R® and R* are not on the atom adjacent to the atom bound to A or C.

   55. A catalyst system as claimed in any one of claims 52 to 54, wherein at least one of R', R? R® and R* is substituted with a polar substituent on the 2™ or further atom from the atom bound to A or C.

   56. A catalyst system as claimed in any one of claims 49 to 55, wherein any polar substituents on one or more of R', R?, R® and R* are electron donating.

   57. A catalyst system as claimed in any one of claims 49 to 56, wherein A and/or C are a potential electron donor for coordination with the transition metal.

   58. A catalyst system as claimed in any one of claims 49 to 57, wherein B is selected from any one of a group comprising: organic linking groups comprising a hydrocarbyi, , substituted hydrocarbyl, heterohydrocarbyl and a substituted heterohydrocarbyl; inorganic linking groups comprising single atom links; ionic links; and a group comprising : methylene, dimethylmethylene, 1,2-ethane, 1,2-phenylene, 1,2-propane, 1,2-catechol,

   1.2-dimethylhydrazine, -B(R®)-, -Si(R%),-, -P(R®)- and -N(R®)- where R® is hydrogen, a hydrocarbyl or substituted hydrocarbyl, a substituted heteroatom and a halogen.

   59. A catalyst system as claimed in any one of claims 49 to 58, wherein B is selected to be a single atom spacer.

   60. A catalyst system as claimed in any one of claims 49 to 59, wherein B is selected to be -N(R®)-, wherein R® is hydrogen or selected from the groups consisting of alkyl, substituted alkyl, aryl, substituted aryl, aryloxy, substituted aryloxy, halogen, nitro, alkoxycarbonyl, carbonyloxy, alkoxy, aminocarbonyl, carbonylamino, dialkylamino, silyl groups or derivatives thereof, and aryl substituted with any of these substituents.

   61. . A catalyst system as claimed in any one of claims 50 to 60, wherein A and/or C is independently oxidised by S, Se, N or O, where the valence of A and/or C allows for such oxidation.

   62. A catalyst system as claimed in any one of claims 50 to 60, wherein A and C is independently phosphorus or phosphorus oxidised by S or Se or N or O.

   63. A catalyst system as claimed in any one of claims 49 to 62, wherein R', R?, R® and R* are independently selected from a group comprising a benzyl, phenyl, tolyl, xyiyl, mesityl, biphenyl, naphthyl, anthracenyl, methoxy, ethoxy, phenoxy, tolyloxy, dimethylamino, diethylamino, methylethylamino, thiophenyl, pyridyl, thioethyl, thiophenoxy, trimethylsilyl, dimethylhydrazyl, methyl, ethyl, ethenyl, propyl, butyl, propenyl, propynyl, cyclopentyl, cyclohexyl, ferrocenyl and tetrahydrofuranyl group.

   64. A catalyst system as claimed in any one of claims 49 to 63, wherein R', R2 R? and R* are independently selected from a group comprising a phenyl, tolyl, biphenyi, naphthyl, thiophenyl and ethyl group.

   65. A catalyst system as claimed in any one of claims 50 to 60 and 62 to 64 wherein : the ligand is selected from any one of a group comprising (3- methoxyphenyl),PN(methyl)P(3-methoxyphenyl),, (4-methoxyphenyl),PN(methyl)P(4- g methoxyphenyl),, (3-methoxyphenyl),PN(isopropyl)P(3-methoxyphenyl),,(4- methoxyphenyl),PN(isopropyl)P(4-methoxyphenyl),, (4-methoxyphenyl),PN(2- ethylhexyl)P(4-methoxyphenyl),, (3-methoxyphenyl)(phenyl)PN(methyl)P(phenyl), and (4-methoxyphenyl)(phenyl)PN(methyl)P(phenyl),, (3-

   methoxyphenyl)(phenyl)PN(methyl)P(3-methoxyphenyl)(phenyl), (4- methoxyphenyl)(phenyl)PN(methyl)P(4-methoxyphenyl)(phenyl), (3- methoxyphenyl),PN(methyl)P(phenyl), and (4-methoxyphenyl),PN(methyl)P(phenyl),, (4- ’ methoxyphenyl),PN(1-cyclohexylethyl)P(4-methoxyphenyl),, (4-methoxyphenyl),PN(2- methylcyclohexyl)P(4-methoxyphenyl),, (4-methoxyphenyl!),PN(decyl)P(4- methoxyphenyl),, (4-methoxyphenyl),PN(pentyl)P(4-methoxyphenyl),, (4- methoxyphenyl),PN(benzyl)P(4-methoxyphenyl),, (4-methoxyphenyl),PN(phenyl)P(4- methoxyphenyl),, (4-fluorophenyl),PN(methyl)P(4-fluorophenyl),, (2- fluorophenyl),PN(methyl)P(2-fluorophenyl),, (4-dimethylamino-phenyl),PN(methyl)P(4- dimethylamino-phenyl),, (4-methoxyphenyl),PN(allyl)P(4-methoxyphenyl),, (phenyl),PN(isopropyl)P(2-methoxyphenyl),, (4-(4-methoxyphenyl)- phenyl).PN(isopropyl)P(4-(4-methoxyphenyl)-phenyl), and (4- methoxyphenyl)(phenyl)PN(isopropyl)P(phenyl)s.

   66. A catalyst system as claimed any one of the claims 49 to 65, wherein the transition metal is selected from any one of a group comprising chromium, molybdenum, tungsten, titanium, tantalum, vanadium and zirconium.

   67. A catalyst system as claimed in any one of the claims 49 to 66, wherein the transition metal is chromium.

   68. A catalyst system as claimed in Claim 67, wherein the transition metal is derived from a transition metal compound selected from a group comprising of an inorganic sal, organic salt, a co-ordination complex and organometallic complex.

   69. A catalyst system as claimed in Claim 68, wherein the transition metal compound is selected from a group comprising chromium trichloride tris-tetrahydrofuran complex, (benzene)tricarbonyl chromium, chromium (lll) octanocate, chromium (lI) acetylacetonoate, chromium hexacarbonyl, and chromium (lll) 2-ethylhexanoate. ) 70. A catalyst system as claimed in any one of claims 49 to 69, wherein the transition metal is selected from a complex selected from chromium (lll) acetylacetonoate and chromium (lil) 2-ethylhexanoate.

   71. A catalyst system as claimed in Claim 68 or Claim 69, wherein the transition ; metal from a transition metal compound and heteroatomic ligand are combined to provide metal/ligand ratios from about 0.01:100 to 10 000:1.

   72. A catalyst as claimed in Claim 71, wherein the transition metal compound and heteroatomic ligand are combined to provide metal/ligand ratios from about 0.1:1 to 10:1.

   73. A catalyst system as claimed in any one of the claims 49 to 72, which includes an activator.

   74. A catalyst system as claimed in Claim 73, wherein the activator is selected from any one of a group consisting of organoaluminium compounds, organoboron compounds, organic salts, such as methyllithium and methylmagnesium bromide, inorganic acids and salts, such as tetrafluoroboric acid etherate, silver tetrafluoroborate and sodium hexafluoroantimonate.

   75. A catalyst system as claimed in Claim 73 or Claim 74, wherein the activator is selected from alkylaluminoxanes.

   76. A catalyst system as claimed in Claim 75, wherein the alkylaluminoxane, or mixtures thereof, is selected from group which consists of methylaluminoxane (MAQ), ethylaluminoxane (EAQ) and modified alkylaluminoxanes (MMAO).

   77. A catalyst system as claimed in Claim 75 or Claim 76, wherein the transition metal and the aluminoxane are combined in proportions to provide Al/metal ratios from about 1:1 to 10 000:1. . 78. A catalyst system as claimed in Claim 77, wherein the transition metal and the aluminoxane are combined in proportions to provide Al/metal ratios from about 1:1 to : 1000:1.

   ) 79. A catalyst system as claimed in Claim 78, wherein the transition metal and the aluminoxane are combined in proportions to provide Al/metal ratios from about 1:1 to 300:1.

   80. A catalyst system as claimed in any one of claims 75 to 79, which includes a trialkylaluminium compound in amounts of between 0.01 to 100 mol per mol of alkylaluminoxane.

   81. Use of a tetramerisation catalyst system as claimed in any one of claims 49 to 80 for the tetramerisation of olefins.

   82. Use of a tetramerisation catalyst system as claimed in any one of claims 49 to 80 for the tetramerisation of ethylene.

   83. Use of a ligand for a tetramerisation process as claimed in any one of claims 1 to and 7 to 48.

   84. Use of a ligand for a tetramerisation catalyst system as claimed in any one of claims 49 to 80.

   83. An olefin tetramerisation process substantially as described herein.

   84. An olefin tetramerisation catalyst system substantially as described herein.