WO2000009584A1

WO2000009584A1 - Catalyst composition and process for the preparation of copolymers of carbon monoxide and an olefinically unsaturated compound

Info

Publication number: WO2000009584A1
Application number: PCT/EP1999/005987
Authority: WO
Inventors: Jan Karel Frederik Buijink; Eit Drent; Jacoba Catherina Lucia Johanna Suykerbuyk
Original assignee: Shell Internationale Research Maatschappij B.V.
Priority date: 1998-08-14
Filing date: 1999-08-12
Publication date: 2000-02-24
Also published as: AU5969799A

Abstract

A catalyst composition which is based upon: (a) a source of nickel cations and (b) a bidentate ligand of the general formula R?1R2M1-R-M2R3R4¿ (I), wherein M?1 and M2¿ represent independently phosphorus, nitrogen, arsenic or antimony, R?1, R2, R3 and R4¿ represent independently optionally substituted hydrocarbyl groups on the understanding that at least one of R?1, R2, R3 and R4¿ represents a substituted aryl group, and R represents a bivalent bridging group of which the bridge which extends directly between the atoms M?1 and M2¿ consists of three bridge atoms of which the middle atom is substituted; and a process for the preparation of copolymers of carbon monoxide and an olefinically unsaturated compound comprising contacting the monomers in the presence of the said catalyst composition.

Description

CATALYST COMPOSITION AND PROCESS FOR THE PREPARATION OF

COPOLYMERS OF CARBON MONOXIDE AND AN OLEFINICALLY

UNSATURATED COMPOUND

The invention relates to a catalyst composition and a process for the preparation of copolymers of carbon monoxide and one or more olefinically unsaturated compounds . Linear copolymers of carbon monoxide with one or more olefinically unsaturated compounds can be prepared by contacting the monomers in the presence of a Group VIII (Groups 8, 9 and 10 in modern notation) metal containing catalyst. The copolymers can be processed by means of conventional techniques into films, sheets, plates, fibres and shaped articles for domestic use and for parts in the car industry. They are eminently suitable for use in many outlets for thermoplastics. In the copolymers in question the units originating from the carbon monoxide on the one hand and the units originating from the olefinically unsaturated compound (s) on the other hand occur in an alternating or substantially alternating arrangement .

So far, the preparation of the copolymers by using catalysts based on palladium as the Group VIII metal has been studied extensively because palladium based catalysts provide a high polymerization rate. However, a disadvantage of using palladium based catalysts is the high palladium price. This high price is to be accepted as a matter of fact because it is caused by the limited natural availability of this metal. Methods for the extraction of palladium remnants from the copolymers which allow the recycle of palladium are available, but these methods introduce additional process steps which complicate the total polymerization process scheme. Another disadvantage is that palladium based catalysts have a tendency to plate-out, i.e. to convert into the^" zero-valent metallic state. Plating-out during the copolymer work-up and further processing may cause some grey discoloration of the copolymer, in particular when its content of catalyst remnants is high. Plating-out may also occur during the catalyst preparation or the storage of the catalyst composition prior to its use in the copolymerization process. The tendency to plate-put is associated with the noble-metal character of palladium based catalysts. It would be desirable to find an alternative to palladium based catalysts.

Many patent applications filed in relation to linear copolymers of carbon monoxide with one or more olefinically unsaturated compounds present a list of possible Group VIII metals. For example EP-A-585493 mentions ruthenium, rhodium, palladium, osmium, iridium, platinum, iron, cobalt and nickel. The great majority of such patent applications state that palladium is the catalytic metal of choice, and include examples only of palladium.

There are, thus, few earlier patent applications which place emphasis on or exemplify the use of nickel in catalysts for the copolymerization of carbon monoxide with olefinically unsaturated compounds. One is

US-A-3984388 which exemplifies the use of nickel cyanide based catalysts. These catalysts, however, displayed a low polymerization activity despite the application of a high polymerization temperature. Moreover, copolymers made with these catalysts contain cyanides as catalyst remnants. It would then be likely that cyanide containing compounds, for example hydrogen cyanide, are being released from the copolymer during its end-use application. This is in particular undesirable when the copolymer is used as a packaging material in contact with food. A second patent application which exemplifies the use of a nickel containing catalyst is EP-A-121965. This suggests the use of catalysts containing nickel, cobalt or, preferably, palladium, in each case complexed with a ligand which is defined as a bidentate ligand of the general formula R!R2-M-R-M-R3R4 in which M represents phosphorous, arsenic or antimony, R represents a divalent organic bridging group having at least 2 carbon atoms in the bridge, none of these carbon atoms carrying substituents that may cause steric hindrance and in which

R1, R2, R3 and R^ are identical or different hydrocarbyl groups. In the examples the divalent bridging group R is a 1,3-propane or 1,4-butane group. However, in those examples of EP-A-121965 in which the copolymer 's molecular weight was determined it was lower than desirable for many applications. Moreover, the polymerisation rates obtained still leave substantial room for further improvements. These comments apply particularly to the single example, test 16, which employed a nickel containing catalyst.

A third patent application which exemplifies a nickel containing catalyst is EP-A-470759. This discloses the use of catalysts based on nickel complexed with a mercaptocarboxylic acid. From the working examples in the latter application it can be comprehended that the polymerization rates achieved were again low.

A fourth patent application which exemplifies nickel containing catalysts is WO 97/00127. In this case more promising nickel containing catalysts were found. They were based upon (a) a source of nickel cations, and (b) a bidentate ligand of the general formula R¹R²M¹-R-M²R³R⁴ wherein M^ and M² represent independently phosphorous, nitrogen, arsenic or antimony, Rl, R² , R3 and R⁴ represent independently optionally substituted hydro- carbyl groups on the understanding that at least one of R¹, R², R³ and R⁴ represents a substituted aryl group, and R represents a bivalent bridging group of which the bridge consists of at most two bridging atoms. The reason for this precise definition of the bridging group R can be found in the examples; the examples of the invention in which R represents an ethane group, for example Examples 1 and 3, show good production of the copolymer; corresponding comparative Examples 2 and 4 in which R represents a 1,3-propane group do not. These results appear to be perfectly consistent with test 16 of EP-A-121965, mentioned above.

It is thus believed that whilst there are many prior art documents making mention of nickel in lists of possible catalytic metals, but emphasising and exemplifying palladium, there is little by way of useful practical disclosure of the use of nickel. The single specification which appears to disclose nickel catalysts of apparent practical value is the somewhat restricted disclosure of WO 97/00127. However, we have now determined further nickel containing catalysts which give good copolymerization rates and/or copolymers of useful molecular weight, of the same order of magnitude as those described in the examples of WO 97/00127. We regard this finding as very surprising, having regard to the prior art, in particular to WO 97/00127 and EP-A-121965. Advantages of this finding are that in a simple and efficient manner copolymers can be prepared using a further cyanide free, non-plating metal containing catalysts. Further, the copolymers thus prepared can have a very low content of catalyst remnants and a good colour performance. The copolymers are in principle free of cyanides.

Furthermore, it appears that the new catalyst compositions offer a significant and entirely unexpected advantage over the catalyst compositions of WO 97/00127, in processes involving the incorporation of olefins other than ethene. The new catalysts appear to facilitate the incorporation of the higher homologues of ethene, for example propene .

Accordingly the invention relates to a catalyst composition which is based upon

(a) a source of nickel cations and

(b) a bidentate ligand of the general formula _R1_R2_M1__R__M2_R3_R4 (_j) wherein M-'- and M² represent independently phosphorous, nitrogen, arsenic or antimony, R^-, R², R³ and R⁴ represent independently optionally substituted hydrocarbyl groups on the understanding that at least one of

R1, R², R³ and R⁴ represents a substituted aryl group, and R represents a bivalent bridging group of which the bridge which extends directly between the atoms M¹ and M² consists of three bridge atoms of which the middle atom is substituted.

The invention also relates to a process for the preparation of copolymers of carbon monoxide and an olefinically unsaturated compound comprising contacting the monomers in the presence of a catalyst composition according to this invention.

In addition this invention relates to a linear copolymer of carbon monoxide and an olefinically unsaturated compound which copolymer comprises nickel in a quantity of up to 500 ppmw relative to the weight of the copolymer and which copolymer is free or substantially free of palladium.

As the source of nickel cations conveniently a nickel salt, such as a nickel (II) salt, is used. Suitable salts include salts of mineral acids such as sulphuric acid, nitric acid, phosphoric acid and sulphonic acids, and organic salts, such as nickel acetylacetonate .

Preferably, a nickel salt of a carboxylic acid is used, for example a carboxylic acid with up to 8 carbon atoms, such as formic acid, acetic acid, trifluoroacetic acid, trichloroacetic acid, propionic acid and citric acid. Other preferred nickel salts are nickel halogenates, such as nickel (II) bromide and nickel (II) iodide. Nickel (II) acetate represents a particularly preferred source of nickel cations . Another very suitable source of nickel cations is a compound of nickel in its zero-valent state, i.e. nickel (0), complexed with an organic ligand, such as a diene or a phosphene. Examples of complexes are nickel (0) tetracarbonyl, nickel (0) bis ( triphenyl- phosphine)- dicarbonyl and nickel (0) dicyclooctadiene, from which cationic species may be formed by reaction, e.g., with a strong acid, such as acids as defined herein, e.g. trifluoroacetic acid. In the ligands of formula (I) M^ and M² preferably represent phosphorous atoms .

Subject to the condition that at least one of the groups R^, R² , R³ and R⁴ must be a substituted aryl group one or more of the definitions of the following paragraphs may be applied, to these groups.

Rl, R², R³ and R⁴ may independently represent hydrocarbyl groups each of which may independently be substituted, suitably by a polar substituent;

R1, R² , R³ and R⁴ may independently represent alkyl, aryl, alkaryl or cycloalkyl groups having typically up to 20 carbon atoms, more typically up to 10 carbon atoms, each of which may independently be substituted, suitably by a polar substituent;

R1, R² , R³ and R⁴ may each independently represent an optionally substituted aryl group, having preferably up to 20 carbon atoms in the ring structure, more preferably up to 10 carbon atoms in the ring structure, most preferably being an optionally substituted phenyl group, with preferred substituents being polar substituents . At least one of R¹ and R² and at least one of R³ and R⁴ preferably represents a substituted aryl group; more preferably each of R¹, R² , R³ and R⁴ represents a substituted aryl group; preferred substituents in each case being polar substituents.

Suitable substituents for substituted aryl group (s) R1, R², R³ and R⁴ include alkyl groups, such as methyl, ethyl or t-butyl groups. However, preferred substituents are polar substituents. Suitable polar substituents for groups R^, R², R³ and

R⁴ include halogen atoms, such as fluorine and chlorine, alkoxy groups such as methoxy and ethoxy groups and alkylamino groups such as methylamino, dimethylamino and diethylamino groups. Preferred alkoxy groups and alkylamino groups contain in particular up to 4 carbon atoms in the/each of their alkyl groups. A preferred polar substituent is an alkoxy group, especially a methoxy group.

Preferred aryl groups are phenyl groups having a substituent at an ortho position with respect to M^ or

M².

It is preferred that substituted aryl groups R1, R ,

R³ and R⁴ are phenyl groups each having a substituent, preferably a polar substituent, as defined above, at an ortho position with respect to M^ or M².

In total the bridging group R preferably has up to 10 carbon atoms, and, optionally, one, two or three heteroatoms, such as silicon, oxygen or nitrogen atoms. The three bridge atoms (by which we mean atoms in the chain between the atoms M^ and M² ) are preferably carbon atoms, but it is also feasible that one, two or three of the bridge atoms are heteroatoms, such as silicon, oxygen or nitrogen atoms. However the middle bridge atom must be substituted - by which we mean it must carry a moiety other than hydrogen. The other two bridge atoms are preferably unsubstituted . When the middle bridge atom is carbon, as is preferred, one or both hydrogen atoms may be substituted. Thus, a preferred bridging group is a 2-substituted 1,3-propane group. In place of one hydrogen atom on the middle bridge atom there may be a substituent R⁵. In place of both hydrogen atoms on the middle bridge atom there may be two substituents R^ and R^ or one substituent R^ , which is joined to the respective carbon atom by a double bond. Preferred ligands have two substituents R^ and R". Preferably they are identical, although this is not essential.

Substituents R^ and R^ may be selected from hydrocarbyl groups generally, for example from optionally substituted (but preferably unsubstituted) alkyl, alkanoate and alkoxy groups, such groups suitably containing up to 6, preferably up to 4, carbon atoms in their alkyl moiety, not including carbon atoms of substituents thereof, and optionally substituted aryl, especially phenyl, groups. Optional substituents of alkyl, alkoxy and alkanoate groups include halogen atoms; cyano groups; alkoxy and haloalkoxy groups having

1-4 carbon atoms; and amino, mono (Cι_ -alkyl) amino and di (C_]__₄_-alkyl) amino groups. Optional substituents of aryl groups include halogen atoms; nitro, hydroxyl and cyano groups; alkyl, alkoxy, haloalkyl and haloalkoxy groups having 1-4 carbon atoms; and amino, mono (C;j__₄_-alkyl) amino and di (C_]__4~alkyl) amino groups. 0-3 substituents may suitably be employed. Preferred halogen atoms within this specification are bromine, chlorine and fluorine atoms. It is believed that the chemical properties of substituents R⁵ and R^ are not especially important as they are selected so as not to participate in the reaction. Rather, it is believed that their conformational properties are more important in that they are thought to cause the catalyst to adopt a suitable ^" shape, with the phosphines suitably located, for useful catalytic action bringing about the copolymerization. Thus, the groups R⁵, R⁶, and R⁷ may be defined in functional terms as comprising hydrocarbyl group (s) facilitating effective copolymerization.

Substituents R^ and R^ are preferably selected from optionally substituted alkyl groups. Unsubstituted alkyl groups are, however, preferred. n-Alkyl groups are preferred to branched alkyl groups. Preferred are alkyl groups having up to 6 carbon atoms, especially those having up to 4 carbon atoms . Most preferred are methyl and ethyl groups . Substituent R' is preferably selected from groups of formula =CH₂, =CHR⁵ and =CR⁵R⁶ where R⁵ and R⁶ are as defined above.

The amount of bidentate ligand supplied may vary considerably, but is usually dependent on the amount of nickel present in the catalyst composition. Preferred amounts of bidentate ligands are in the range of from 0.1 to 8, more preferably in the range of from 0.5 to 2 moles per gram atom of nickel, most preferably 1.0-1.5 moles per gram atom of nickel. The nickel containing catalyst compositions may be based on another additional component which functions during the copolymerization as a source of anions which are non- or only weakly co-ordinating with nickel under the conditions of the copolymerization. Typical additional components are, for example, protic acids, salts of protic acids, Lewis acids, acids obtainable by combining a Lewis acid and a protic acid, and salts derivable from such combinations. Suitable are strong protic acids and their salts, which strong protic acids have in particular a pKa of less than 6, more in particular less than 4, preferably less than 2, when measured in aqueous solution at 18 °C . Examples of suitable protic acids are the above mentioned acids which may also participate in the nickel salts, e.g. perchloric acid and trifluoroacetic acid. Other suitable protic acids are adducts of boric acid and 1,2-diols, catechols or salicylic acids. Salts of these adducts may be used as well. Suitable Lewis acids are, for example, BF3, BF5,

SnCl₂, SnF₂, AIF3, AsF₅, Sn(CF₃S0₃)₂, Sn(CH₃S0₃)₂, and also hydrocarbylboranes, such as triphenylborane, tris- (perfluorophenyl) borane and tris [bis-3, 5- (trifluoro- methyl) phenyl] borane . Protic acids with which Lewis acids may be combined are for example sulphonic acids and hydrohalogenic acids, in particular HF. A very suitable combination of a Lewis acid with a protic acid is tetrafluoroboric acid (HBF4) or hexafluorophosphoric acid

(HPFg) . Other compounds which function during the copolymerization as a source of anions which are non- or weakly co-ordinating with nickel are salts which contain one or more hydrocarbylborate anions or carborate anions, such as sodium tetrakis [bis-3, 5- (trifluoromethyl) phenyl] - borate, lithium tetrakis (perfluorophenyl) borate and cobalt carborate (Co (B; CHI_ ) ₂ ) . Again other compounds which may be mentioned in this context are aluminoxanes, in particular methyl aluminoxanes and t-butyl aluminoxanes .

The amount of the additional component which functions during the copolymerization as a source of anions which are non- or only weakly co-ordinating with nickel is preferably selected in the range of 0.1 to 50 equivalents per gram atom of nickel, in particular in the range of from 0.5 to 25 equivalents per gram atom of nickel. However, the aluminoxanes may be used in such quantity that the molar ratio of aluminium to nickel is in the range of from 4000:1 to 10:1, preferably from 2000:1 to 100:1.

The amount of catalyst composition used in the process of the invention may vary between wide limits. Recommended quantities of catalyst composition are in the range of 10^~° to 10^~2, calculated as gram atoms of nickel per mole of olefinically unsaturated compound to be copolymerised with carbon monoxide. Preferred quantities are in the range of 10^-"^ to 10^-3 on the same basis. The performance of nickel containing catalyst compositions in the copolymerization process may be improved by introducing an organic oxidant, such as a quinone or an aromatic nitro compound. Preferred oxidants are quinones selected from the group consisting of benzoquinone, napththoquinone and anthraquinone . When the process is carried out as a gas phase process, the quantity of oxidant is advantageously in the range of from 1 to 500, preferably in the range of from 1 to 100 mole per gram atom of nickel. The copolymerization process is usually carried out at a temperature between 20 and 200 °C, preferably at a temperature in the range of from 30 to 150 °C, and usually applying a pressure between 0.1 and 20 MPa, pressures in the range of from 1 to 10 MPa being preferred.

Olefinically unsaturated compounds which can be used as monomers in the copolymerization process of the invention include compounds consisting exclusively of carbon and hydrogen and compounds which in addition comprise hetero atoms, such as unsaturated esters, ethers and amides. Unsaturated hydrocarbons are preferred. Examples of suitable olefinic monomers are lower olefins, such as ethene, propene and butene-1, cyclic olefins such as cyclopentene, aromatic compounds, such as styrene and α-methylstyrene and vinyl esters, such as vinyl acetate and vinyl propionate. Most preference is given to ethene as the sole olefinically unsaturated compound, and to mixtures of ethene with another olefinically unsaturated compound, in particular an α-olefin, such as butene-1, or, especially, propene. The term "lower" used in this document to specify an organic compound has the meaning that the organic compound contains up to 6 carbon atoms .

The catalyst compositions of the invention offer a surprising advantage over prior nickel catalyst compositions in their ability to copolymerize carbon monoxide with ethene in admixture with a higher homologue, especially propene.

Generally, the molar ratio of on the one hand carbon monoxide and on the other hand the olefinically unsaturated compound (s) used as monomer is selected in the range of 1:10 to 10:1. Preferably the molar ratio is in the range of 1:5 to 5:1, more preferably in the range 1:2 to 2:1. Substantially equimolar ratios are most preferred.

Hydrogen may be present in processes employing the catalyst compositions of the invention. Hydrogen may act as a chain transfer agent and so play a part in controlling the molecular weight of the copolymers formed. However hydrogen is not needed for a reaction to take place with good yield. Accordingly, whilst hydrogen may be present, for simplicity at least it is preferred in many embodiments to employ the catalyst compositions in such processes in the absence of hydrogen.

The process of the invention is conveniently carried out in the presence of a diluent. Preferably a diluent is used in which the copolymers are insoluble or virtually insoluble so that they form a suspension upon their formation. Aromatic solvents, such as alkylbenzenes, for example toluene and xylenes, may be used. Halogenated alkanes may be used, for example dichloromethane . Recommended diluents are polar organic liquids, such as ketones, for example acetone, and ethers, esters and amides. Protic liquids are favoured for many embodiments, for example monohydric and dihydric alcohols, in particular alcohols having at most 4 carbon atoms per molecule, such as methanol and ethanol . Protic liquids may advantageously contain a minor quantity of water, for example 0.1-10 %vol, preferably 0.2-5 %vol, based on the total volume of the protic liquid. The process of this invention may also be carried out as a gas phase process, in which case the catalyst is typically used deposited on a solid particulate material or chemically bound thereto. The process may also be carried out as an emulsion polymerisation reaction.

When a diluent is used in which the formed copolymer forms a suspension it is preferred to have a solid particulate material suspended in the diluent before the monomers are contacted with the catalyst composition. Suitable solid particulate materials are silica, polyethene and a copolymer of carbon monoxide and an olefinically unsaturated compound, preferably a copolymer which is based on the same monomers as the copolymer to be prepared. The quantity of the solid particulate material is preferably in the range of from 0.1 to 20 g, particularly from 0.5 to 10 g per 100 g diluent.

The copolymers can be recovered from the poly- merization mixture by using conventional techniques. When a diluent is used the copolymers may be recovered by filtration or by evaporation of the diluent. The copolymer may be purified to some extent by washing.

Copolymers are suitably prepared in which the units originating from carbon monoxide on the one hand and the units originating from the olefinically unsaturated compound (s) on the other hand occur in an alternating or substantially alternating arrangement. The term "substantially alternating" will generally be understood by the skilled person as meaning that the molar ratio of the units originating from carbon monoxide to the units originating from the olefinically unsaturated compound (s) is above 35:65, in particular above 40:60. When the ratio is 50:50, as is preferred, the copolymers are believed to be perfectly alternating. A high Limiting Viscosity Number (LVN) , or intrinsic viscosity, of the copolymers is indicative of a high molecular weight. The LVN is calculated from determined viscosity values, measured for different copolymer concentrations in m-cresol at 60 °C . It is preferred to prepare copolymers having an LVN in the range of from 0.1 to 10 dl/g, in particular from 0.2 to 8 dl/g, more preferably from 0.5 to 6 dl/g, and especially 0.6 to 3 dl/g. It is also preferred to prepare copolymers which have a melting point above 150 °C, as determined by Differential Scanning Calorimetry (DSC) . For example, linear copolymers of carbon monoxide and ethene and linear copolymers of carbon monoxide, ethene and another α-olefin which are alternating or substantially alternating fall into this category. It is particularly preferred to prepare linear alternating copolymers of carbon monoxide and ethene or linear alternating copolymers of carbon monoxide, ethene and another α-olefin in which the molar ratio of the other α-olefin to ethene is typically above 1:500, especially above 1:200, preferably in the range of from 1:100 to 1:1, more preferably in the range of from 1:60 to 1:2.

Furthermore, for practical reasons the nickel content of the copolymers will typically be above 0.01 ppmw, relative to the weight of the copolymer. It is preferred to prepare copolymers which have a nickel content in the range of from 0.05 to 300 ppmw, in particular from 0.1 to 200 ppmw, relative to the weight of the copolymer. The copolymers are preferably substantially free, and more preferably entirely free, of palladium. "Substantially free of palladium" means to the skilled person that the palladium content is lower than the value normally achieved when a palladium based catalyst is employed in the copolymerization, for example less than 1 ppmw, in particular less than 0.1 ppmw, relative to the weight of the copolymer. Alternatively it is preferred that, if palladium is present, the weight ratio of palladium to nickel is less than 1:50, especially less than 1:100, most preferably less than 1:200.

Preferably the copolymers are entirely free or substantially free of inorganic cyanides. Substantially free of organic cyanides may be considered copolymers of which the content of inorganic cyanide, measured as the weight of CN, is less than 10 ppm, especially less than 1 ppm, most preferably less than 0.1 ppm, relative to the weight of the copolymer. The copolymer 's content of cyanide can be determined by bringing the cyanide into an aqueous solution, for example by dissolving the copolymer in a suitable polar solvent, such as hexafluoroiso- propanol, and adding water, after which the cyanide content of the aqueous solution can be determined using standard methods.

The process of the invention may be carried out as a batch process or as a continuous process.

The invention is illustrated by the following examples of the preparation of linear alternating carbon monoxide/olefin copolymers. Example 1

A carbon monoxide/ethene copolymer was prepared as follows .

A stirred 200 ml autoclave was charged with a catalyst solution consisting of 50 ml of methanol, 0.1 mmol of nickel (II) acetate, 0.1 mmol of 1, 3-bis [bis (2-methoxyphenyl) phosphino] 2 , 2-diethylpropane and 0.25 mmol of tetrafluoroboric acid.

The air in the autoclave was removed by evacuation. The autoclave was then pressurized with ethene to 40 bar and additionally with 5 bar carbon monoxide, i.e., a total of ethene and carbon monoxide of 45 bar. Subsequently the autoclave was heated to 90 °C . The autoclave was then repressurized 4 times every 0.1 hrs with 5 bar additional carbon monoxide. After 1.5 hrs the polymerization was terminated by cooling to ambient temperature and subsequently releasing the pressure. The copolymer was recovered by filtration and allowed to dry.

The yield was 13.4 g of a yellowish white copolymer having an LVN of 1.6 dl/g, which corresponds to a number average molecular weight of about 24000. Example 2

A carbon monoxide/ethene copolymer was prepared as follows .

A stirred 200 ml autoclave was dried overnight at 100 °C at a reduced pressure. After cooling down to ambient temperature the autoclave was pressurized 3 times with 70 bar of nitrogen, each time followed by release of the pressure. The autoclave was then charged with a catalyst solution consisting of 50 ml of methanol 0.1 mmol of { 1, 3-bis [bis (2-methoxyphenyl) phosphino] -2, 2- diethylpropane } (II) nickel dimethyl and 0.1 mmol of trifluoromethanesulfonic acid.

The catalyst solution was prepared separately in a Schlenk flask under nitrogen and transferred to the autoclave with a syringe while slowly purging the autoclave with nitrogen. The autoclave was then pressurized with carbon monoxide to 5 bar and additionally with 40 bar of ethene, i.e., a total of ethene and carbon monoxide of 45 bar. Subsequently, the autoclave was heated to 80 °C . The autoclave was then repressurized 5 times every 0.05 hrs with 5 bar additional carbon monoxide. After 2 hrs the polymerization was terminated by cooling to ambient temperature and subsequently releasing the pressure. The copolymer was recovered by filtration, washing with methanol and drying at 60 °C in nitrogen at a reduced pressure .

The yield was 14.7 g of a yellowish white copolymer having an LVN of 2.0 dl/g, which corresponds to a number average molecular weight of about 30000. Example 3

A carbon monoxide/ethene/propene terpolymer was prepared as follows .

A stirred 250 ml autoclave was charged with a catalyst solution consisting of 50 ml of methanol, 0.1 mmol of nickel (II) acetate, 0.1 mmol of 1, 3-bis [bis (2-methoxyphenyl) phosphino] -2, 2-diethylpropane and 0.25 mmol of tetrafluoroboric acid.

The air in the autoclave was removed by evacuation. The autoclave was then pressurized with ethene to 20 bar and additionally with 10 bar carbon monoxide, i.e., a total of ethene and carbon monoxide of 30 bar. Subsequently, 30 ml of liquid propene was pumped in the autoclave. The autoclave was heated at 80 °C . After 0.25 hrs again 6 bar of carbon monoxide was introduced. The reaction was terminated by cooling after 1 hr .

After pressure release 6.5 gram of terpolymer was isolated by filtration. 13C NMR analysis showed that 2% of the ethene moieties had been randomly displaced by propene units. The copolymer had an LVN of 0.7 dl/g, which corresponds to a number average molecular weight of about 10500. Example 4

Example 3 was repeated with the difference that 50 ml of liquid propene was additionally introduced. The reaction temperature was 92 °C . Over a period of 2 hrs again 10 bar of carbon monoxide (in five portions of 2 bar) was introduced.

At the end of this period 13.1 gram of terpolymer was recovered. 13C NMR showed that 3% of ethene units were randomly displaced by propene units. The copolymer had an LVN of 0.5 dl/g, which corresponds to a number average molecular weight of about 7500. Example 5

A carbon monoxide/ethene copolymer was prepared as follows.

A stirred 250 ml autoclave was charged with a catalyst solution consisting of 50 ml of methanol, 0.1 mmol of nickel (II) acetate, 0.12 mmol of 1, 3-bis [bis (2-methoxyphenyl) phosphino] -2, 2- dimethylpropane and 0.5 mmol of trifluoroacetic acid.

The air in the autoclave was removed by evacuation. The autoclave was then pressurized with ethene to 30 bar and additionally with 10 bar carbon monoxide, i.e. a total of ethene and carbon monoxide of 40 bar. Subsequently the autoclave was heated to 90 °C . The autoclave was the repressurized 4 times every 0.1 hrs with 5 bar additional carbon monoxide. After 0.25 hrs the polymerization was terminated by cooling to ambient temperature and subsequently releasing the pressure. The copolymer was recovered by filtration and allowed to dry. The yield was 16.3 g of copolymer. The LVN was not measured. Carbon monoxide consumption was virtually complete . Example 6 A carbon monoxide/ethene copolymer was prepared as follows .

A stirred 500 ml autoclave was dried overnight at 25 °C at a reduced pressure. The autoclave was pressurized 2 times with 50 bar of a 1:1 mixture of carbon monoxide and ethene, each time followed by release of the pressure. The autoclave was then charged with 250 ml of anhydrous, degassed methanol. Subsequently the autoclave was heated to 90 °C . The autoclave was then pressurized with 40 bar of ethene. Then, a solution of 0.017 mmol of { 1, 3-bis [bis (2-methoxyphenyl) phosphino] - 2, 2-diethylpropane } nickel (II) methyl trifluoromethane sulfonate in 5 ml of methanol was injected. The pressure was raised further with 1:1 carbon monoxide/ethene to 50 bar and kept constant during the polymerization by supplying this gas. The polymerization was started by the injection of 0.1 mmol of trifluoromethanesulfonic acid in 2 ml methanol .

After 1 hour the polymerization process was terminated by cooling to ambient temperature and subsequently releasing the pressure. The copolymer was recovered by filtration, washed with methanol and dried at 60 °C in nitrogen at a reduced pressure.

The yield was 6.5 g of a copolymer with a number average molecular weight of 51000 (by l^C) . Example 7 A carbon monoxide/ethene copolymer was prepared as described in Example 6, but with the differences that 0.014 mmol of { 1, 3-bis [bis (2-methoxyphenyl) phosphino] - 2, 2-diethylpropane} nickel (0) dicarbonyl dissolved in 4 ml of dichloromethane was used instead of {l,3-bis[bis (2-methoxyphenyl) phosphino] -2, 2-diethylpropane} nickel (II) methyl trifluoromethane sulfonate, 5.4 g of carbon monoxide/ethene copolymer as seed material was used and the order of addition of catalyst and acid was reversed. The yield, corrected for seed material, was 10.5 g of a copolymer having an LVN of 0.8 dl/g, which corresponds to a number average molecular weight of about 12000. Example 8 (comparative)

Example 3 was repeated with the difference that 1,3 bis [di-2-methoxyphenyl) phosphino] propane was used as the ligand. After 2 hrs at 80 °C only a trace of polymer had been formed. Example 9 (comparative)

Example 8 was repeated with the difference that 5 bar of hydrogen was additionally present. After 2 hrs at 80 °C only a trace of polymer had been formed. Example 10 (comparative)

Example 3 was repeated with the difference that 0.12 mmol of 1, 2-bis [ (di-2-methoxyphenyl) phosphino] ethane was used as ligand instead of 0.12 mmol 1, 3-bis [di- (2- methoxyphenyl) phosphino] -2, 2-diethylpropane. After a reaction time of 5 hrs at 80 °C, 5.6 gram of polymer had been formed. Analysis by 13 C NMR showed that only 1% of ethene units were displaced by propene units. Example 11 (comparative) A carbon monoxide/ethene copolymer was prepared as follows .

A stirred 250 ml autoclave was charged with a catalyst solution consisting of 50 ml of methanol, 0.1 mmol of nickel (II) acetate, 0.12 mmol of (diphenylphosphino] -2, 2-diethylpropane, and 0.5 mmol of trifluoroacetic acid.

The air in the autoclave was removed by evacuation. The autoclave was then pressurized with ethene to 30 bar and additionally with 10 bar carbon monoxide, i.e. a total of ethene and carbon monoxide of 40 bar.

Subsequently the autoclave was heated to 90 °C . After 5 hrs only traces of copolymer had been formed. Example 12 (comparative)

Example 11 was repeated except that 0.5 mmol of tetrafluoroboric acid was used instead of trifluoroacetic acid. Again, only traces of polymer were observed after 5 hrs .

In all of the Examples in which LVN was determined, it was determined in m-cresol as solvent at 60 °C .

Claims

C L A I M S

1. A catalyst composition which is based upon

(a) a source of nickel cations and

(b) a bidentate ligand of the general formula

_R1_R2_M1__R__M2_R3_R4 _(I) wherein M-'- and M² represent independently phosphorous, nitrogen, arsenic or antimony, R^, R², R³ and R⁴ represent independently optionally substituted hydrocarbyl groups on the understanding that at least one of R¹, R², R³ and R⁴ represents a substituted aryl group, and R represents a bivalent bridging group of which the bridge which extends directly between the atoms M^ and M² consists of three bridge atoms of which the middle atom is substituted.

2. A catalyst composition as claimed in claim 1, characterized in that the source of nickel cations comprises a nickel salt or a compound of nickel (0) complexed with an organic ligand.

3. A catalyst composition as claimed in claim 1 or 2 , characterized in that M¹ and M² represent phosphorous atoms. . A catalyst composition as claimed in any preceding claim, characterized in that at least one of R1 and R , and at least one of R³ and R⁴ represents an aryl group substituted by a polar substituent. 5. A catalyst composition as claimed in any preceding claim, characterized in that at least one of R1, R , R³ and R⁴ represents a phenyl group substituted at an ortho position with respect to M^ or M² by a polar substituent.

6. A catalyst composition as claimed in claim 4 or 5, wherein a said polar substituent is an alkoxy group, especially a methoxy group.

7. A catalyst composition as claimed in any of claims 1-6, characterized in that the bivalent bridging group R is a 1,3-propane group of which the middle carbon atom is disubstituted.

8. A catalyst composition as claimed in claim 7, wherein the bivalent bridging group R is a 1,3-propane group of which the middle atom is disubstituted by Cι_4 alkyl groups .

9. A process for the preparation of copolymers of carbon monoxide and an olefinically unsaturated compound comprising contacting the monomers in the presence of a catalyst composition as claimed in any of claims 1-8.

10. A process as claimed in claim 9, characterized in that the olefinically unsaturated compound in an unsaturated hydrocarbon, especially ethene or a mixture of ethene with another α-olefin. 11. A process as claimed in claim 9 or 10, characterized in that the contacting is carried out in a diluent in which the copolymers are insoluble or virtually insoluble, such as methanol or ethanol, so that they form a suspension upon their formation, using such an amount of the catalyst composition that the amount of nickel present is in the range of from 10^~8 to 10^-2 gram atom, preferably 10^"^ to 10^-3 gram atom, per mole of olefinically unsaturated compound to be copolymerized, and applying a molar ratio of carbon monoxide to the olefinically unsaturated compound (s) in the range of from 1:5 to 5:1, preferably from 1:2 to 2:1, a temperature between 20 and 200 °C, in particular between 30 and 150 °C, and a pressure between 0.1 and 20 MPa, in particular between 1 and 10 MPa.

12. A linear copolymer of carbon monoxide and an olefinically unsaturated compound prepared by a process as claimed in any preceding claim, which copolymer comprises nickel in a quantity not exceeding 500 ppmw relative to the weight of the copolymer and which copolymer is free or substantially free of palladium.

13. A copolymer as claimed in claim 12, characterized in that the copolymer has a nickel content in the range of from 0.05 to 300 ppmw, in particular from 0.1 to 200 ppmw, relative to the weight of the copolymer.

14. A copolymer as claimed in claim 12 or 13, characterized in that if palladium and/or inorganic cyanide are present, the content of palladium is less than 1 ppm and the content of inorganic cyanide is less than 10 ppm, calculated as with weight of CN, both contents being relative to the weight of the polymer.

15. A copolymer as claimed in any of claims 12-14, characterized in that the copolymer is a linear alternating copolymer of carbon monoxide and ethene or a linear alternating copolymer of carbon monoxide, ethene and another α-olefin.