The oligomeric polyketones used in the invention can be prepared by carbonylation of alkenes by reaction with carbon monoxide. This process is known and useful products of the reaction include ketone polymers and carboxylic acids or esters. However, it is believed that the use of oligomeric products of this process as lubricant compositions, as described in this invention, is novel.

Accordingly, the invention comprises a lubricant composition comprising an oligomeric polyketone which is a fluid and which is obtainable by reacting an alkene containing from 4 to 20 carbon atoms with carbon monoxide.

The oligomeric polyketone used in the lubricant composition of the invention is fluid, by which is taken to mean that the material will flow at room temperature. More specifically, a material which has a viscosity of less than 0.1 m2 s-at 20° C is generally considered to be a fluid.

The compounds used in this invention are polyketones, i. e. compounds which contain more than one C=O group.

In general, these compounds are oligomers which contain repeat units having the following structures. in which R is a branched or linear alkyl group containing from 2 to 18 carbon atoms.

Usually, the oligomer will have a preponderance of repeatng units of type (b) or (c) [ketone repeat units] and repeat units of type (a) [alkane repeat units] may be absent.

Preferably the average number of repeat units [type (a) plus type (b) plus type (c)] in the oligomers of the invention is in the range 3 to 10 and more preferably is in the range 3 to 8.

The group R-CH-CH2 which is present in all of the repeating units is derived from the alkene which can be used to prepare the oligomers used in the invention and this alkene may be linear or branched. Preferably, R is an alkyl group containing from 2 to 18 carbon atoms.

The lubricant compositions of the invention comprise oligomeric ketones and those of particular use have a viscosity at 40 ° C in the range 2 to 1000 mm 2 s-'. The flash point of oligomers used in the invention is preferably higher than 120 ° C and more preferably higher than 200° C. Also, the lubricant compositions preferably have a pour point less than 0 ° C and more preferably less than-20 ° C when determined by ASTM D97. A further desirable property of the oligomers used in the invention is a viscosity index as defined by ASTM D2270-93 of at least 50 and preferably at least 100 Another aspect of the invention comprises the use in a lubricating composition of an oligomeric polyketone which is a fluid and which is obtainable by reacting an alkene containing from 4 to 20 carbon atoms with carbon monoxide.

In another aspect, the invention comprises a method of providing lubrication comprising using in a lubricating composition an oligomeric polyketone which is a fluid and which is obtainable by reacting an alkene containing from 4 to 20 carbon atoms with carbon monoxide.

The oligomeric polyketone may be used as either a major component, i. e. greater than 75%, or a minor component, i. e. less than 25%, in the lubricating composition.

A convenient method for the production of the oligomeric polyketones used in the invention is the reaction of a suitable alkene with carbon monoxide in the presence of a catalyst which is obtainable by combining a metal of one of Groups 8 to 11 or a compound thereof and a bidentate ligand which is a compound of a Group 15 or Group 16 element.

Suitable metals of Groups 8 to 11 include cobalt, nickel, palladium, rhodium, platinum, copper, silver and gold. Particularly preferred are platinum or palladium. Suitable compounds of such metals of Groups 8 to 11 include salts of such metals with, or compounds comprising, weakly co-ordinated anions derived from the following acids: nitric acid; sulphuric acid; lower alkanoic (up to C 12) acids such as acetic acid and propionic acid; sulphonic acids such as methane sulphonic acid, chlorosulphonic acid, fluorosulphonic acid, trifluoromethane sulphonic acid, benzene sulphonic acid, naphthalene sulphonic acid, toluene sulphonic acid, e. g. p-toluene sulphonic acid, t-butyl sulphonic acid, and 2-hydroxypropane sulphonic acid; sulphonated ion exchange resins ; perhalic acids such as perchloric acid; perfluororated carboxylic acids such as trichloroacetic acid and trifluoroacetic acid; orthophosphoric acid; phosphonic acids such as benzene phosphonic acid; and acids derived by interaction between a Lewis acid such as boron trifluoride, phosphorus pentafluoride, arsenic pentafluoride, antimony pentafluoride, tantalum pentafluoride or niobium pentafluoride with a Bronsted acid such as hydrogen fluoride.

Other sources which may provide suitable anions include tetraphenyl borate and its derivatives such as tetrakis [3,5-bis (trifluoromethyl) phenyl] borate and tetrakis (pentafluorophenylborate). Suitable weakly-or non-coordinating anions are generally known in the art and are described, for example in W. Beck et al., Chem. Rev., vol. 88, p. 1405-1421 (1988) and S. H. Strass, Chem. Rev. Vol 93, p. 927-942 (1993).

Additionally, zero valent palladium compounds with labile ligands, e. g. tris (dibenzylideneacetone) dipalladium and tetrakis (triphenylphosphine) palladium, may be used in conjunction with the above acids.

Particularly useful bidentate ligands have the general structure given below

wherein X is a bivalent organic bridging group, E'and E 2 are, independently, an element of Group 15 or Group 16 and R'to R 4 are, independently, substituted or unsubstituted aliphatic, cycloaliphatic, aromatic or heterocyclic groups or one or both of the entities R'-E'-R2 and R3-E2-R4 represent a substituted or unsubstituted cyclic group with at least 5 ring atoms.

The bivalent organic bridging group X is suitably an alkylene group, which may be branched, or a carbon chain interrupted by a hetero atom, such as an oxygen atom, or an, optionally substituted, aryl moiety to which the Group 15 or 16 atoms, E'and E2 are linked on available adjacent carbon atoms. When X is a linear alkylene group, it preferably contains 1 to 4 carbon atoms. Particularly suitabie alkylene groups include the 1,3-propylene, 2,2'-diethyl-1, 3-propylene, 2,4-butylene, 2-methyl-2'-benzyl-1,3-propylene and 1,2-ethylene groups. The synthesis of some suitable diphenylphosphino substituted bidentate ligands is described by Bianchini et al. in Macromolecules 1999, 32,4183-4193.

When X is a substituted aryl moiety examples of preferable bridging groups include ortho-xylyl, 2,3-dimethylnaphthyl and 3,4-dimethylnaphthyl. Examples of bidentate ligands- having substituted aryl backbones are bis (diphenylphosphino)-o-xylene (also known as 1,2-bis (diphenylphosphinomethyl) benzene and bis (4,8, dimethyl-2-phosphabicyclo- [3,3,1] nonyl)-o-xylene (also known as limphos). Where the bridging group X contains an aryl moiety, e. g. a phenyl group, this may optionally be substituted. Substituents may be organic groups, e. g. alkyl, particularly C, to C 8l aryl, alkoxy, carbalkoxy, halo, nitro,

trihalomethyl or cyano. Alternatively, the aryl moiety may be a fused polycyclic group such as naphthalene, biphenylene or indene.

E'and E'are, independently, an element of Group 15 or Group 16 but, preferably E and E 2 are the same element. Preferably, E'and E 2are phosphorus, nitrogen, arsenic, antimony or sulphur and especially preferred ligands are those in which both E'and E are phosphorus or nitrogen.

When R'to R 4are aliphatic groups, they may be branched or linear and preferably they contain up to 20 carbon atoms. More preferably, they contain up to 10 carbon atoms and suitable groups include methyl, ethyl, propyl, iso-propyl, n-butyl, sec-butyl, tertiary butyl, neopentyl, adamantyl and cyclohexyl groups.

When R'-E'-R and/or R3-E2-R'represent cyclic groups, these groups contain at least 5 ring atoms and preferably from 6 to 9 ring atoms. Preferred cyclic groups are those in which R 1 with R 2 and/or R 3with R 4 represent 1,4-cyclohexylene, 1,4-cycloheptylene, 1,3-cycloheptylene, 1,2-cyclooctylene, 1,3-cyclooctylene, 1,4-cyclooctylene, 1,5-cyclo- octylene, 2-methyl-1,5-cyclooctylene, 2,6-dimethyl-1, 4-cyclooctylene, 2,6-dimethyl- 1,5-cyclooctylene, 4-vinylcyclohexene, norbornene, 5-methylene-2-norbornene, 5-ethylidene-2-norbornene, 5-vinyl-2-norbornene, R- (+)-limonene, and S- (-)-limonene groups.

When R'to R are aromatic groups they preferably contain not more than 18 carbon atoms, and particularly 6 to 14 carbon atoms. Examples of suitable groups are substituted or unsubstituted naphthyl groups and, preferably, substituted or unsubstituted phenyl groups. Suitable substituents are halogen atoms and alkyl, aryl, alkoxy, carboxy, carboalkoxy, acyl, trihalogenomethyl, cyano, dialkylamino, sulphonyl alkyl and alkanoyloxy groups.

When R'to R 4are heterocyclic groups they preferably contain not more than 18 carbon atoms, and particularly 6 to 14 carbon atoms. Examples of suitable groups are

pyrrole and substituted pyrroles, furan, 2-methylfuran, thiophene, pyridine and substituted pyridines and bipyridine.

Particularly preferred bidentate ligands include bis (diphenyl-phosphino)-o-xylene (also known as 1,2-bis (diphenylphosphinomethyl) benzene), bis (4,8, dimethyl-2-phosphabi- cycio [3,3,1] nonyl)-o-xylene (also known as limphos), 1,3-bis (diphenylphosphino) propane and 1,3-bis (diphenylphosphino)-2, 2'-diethylpropane.

The amount of bidentate ligand used can vary within wide limits. Preferably, the bidentate ligand is present in an amount such that the ratio of the number of moles of the bidentate ligand present to the number of moles of the metal of Groups 8 to 11 present is from 1: 1 to 1: 50, e. g. 1 : 1 to 1: 10 and particularly from 1: 1 to 1 : 5.

In this process for preparing the oligomers of the invention carbon monoxide and alkene are mixed in the presence of the catalyst. Gases other than carbon monoxide and which are inert in the reaction may also be present. Examples of such gases include hydrogen, nitrogen, carbon dioxide and the noble gases such as argon.

Preferably the catalyst is preformed before mixing with other ingredients of the reaction mixture. Typically, a solution of the ligand in, for example, an aromatic hydrocarbon is mixed with a solution of the metal compound in the same solvent at a temperature below about 60 ° C. Suitable solvents include benzene, toluene, isomers of xylene, mesitylene, dichloromethane and tetrahydrofuran. Frequently, some of the catalyst will precipitate out as the reaction proceeds but the yield can often be improved by evaporating the solvent.

The isolated solid catalyst is then washed and dried before use.

The process for preparing oligomers of the invention is preferably carried out at a temperature from 60 to 120° C, and particularly from 90 to 100° C.

Usually, the process is conducted under a total pressure of from 1 x 10 5 N m-2 to 100 x 105 N m~2 and in particular from 5 x 105 N m2 to 50 x 10OS N m-2 In the process for preparing oligomers used in the invention the catalyst system may be used homogeneously or heterogeneously. Preferably, the catalyst system is used

homogeneously. The catalyst system is preferably in the liquid phase of the reaction mixture which may be formed by one or more of the reactants or by the use of a suitable solvent.

Suitable solvents that may be used include one or more aprotic solvents such as ethers, e. g. diethyl ether, dimethyl ether, dimethyl ether of diethylene glycol, anisole and diphenyl ether; aromatic compounds, including halo variants of such compounds, e. g. benzene, toluene, ethyl benzene, o-xylene, m-xylene, p-xylene, chlorobenzene, o-dichlorobenzene, m-dichlorobenzene, and p-dichlorobenzene; alkanes, including halo variants of such compounds, e. g. hexane, heptane, 2,2,3-trimethylpentane, methylene chloride and carbon tetrachloride; nitriles, e. g. benzonitrile and acetonitrile; esters, e. g. methyl benzoate, methyl acetate and dimethyl phthalate; sulphones, e. g. diethyl sulphone and tetrahydrothiophene 1,1-dioxide; amides, including halo variants of such compounds, e. g. dimethyl formamide and N-methyl pyrrolidone as well as protic solvents such as alcohols Preferred alcohols include methanol, ethanol, isopropanol, n-propanol and butanol.

The amount of catalyst used can be varied quite widely, but, typically, is in the range 1 part catalyst to from 2000 to 5000 parts olefine by weight.

The yield of oligomer can frequently be improved by carrying out the reaction between carbon monoxide and olefine in the presence of an oxidant. Typical oxidants include 1,4-quinonic compounds such as 1,4-benzoquinone or 1,4-naphthaquinone and nitro compounds such as nitrobenzene or nitrofluoroborate (NOBF4).

When used, the amount of oxidant present is usually sufficient to provide a molar ratio of metal to oxidant in the range 1: 1 to 1: 10 and, preferably, in the range 1: 1 to 1: 5.

The reaction conditions can be arranged so that the desired oligomeric ketone is produced as a separate phase from the remaining reactants, thus leading to a more easily isolated product.

The oligomeric ketones may optionally be further subjected to catalytic hydrogenation in order to remove any residual olefinic unsaturation present in the materials as produced and thereby increase the stability of the resulting materials. Such catalytic hydrogenation processes are well known and are described in standard reference texts such as Ullmann's Encyclopaedia of Industrial Chemistry, Volume A13, p. 487, Hydrogenation and dehydrogenation (P N Rylander).

The lubricating compositions of the invention are suitable for use in mechanicai devices, principally acting as lubricants, but also capable of performing as functional fluids, for example as heat transfer fluids or hydraulic fluids. They are useful in internal combustion engines, in gear mechanisms, in hydraulic systems and in other mechanical devices such as air compressors or gas compressors for refrigeration. They are also useful as lubricants in industrial processes including metal working, textile manufacture etc. The oligomeric ketones may be used alone or mixed with other materials commonly used as lubricants or functional fluids, such as mineral oils or synthetic oils such as hydrocarbons (e. g. poly alphaolefins, poly (isobutylenes) or alkylbenzenes), esters including phosphate esters or polyalkylene oxides. The oligomeric ketones may be used as modifying components with such other materials in levels ranging from 1 to 10% of the lubricant composition.

The lubricant compositions of the invention are frequently formulated with conventional additives such as oxidation inhibitors, metal or copper deactivators, corrosion inhibitors, antiwear agents, extreme pressure agents, antifoaming agents, detergents, dispersants, pour point depressants and friction modifiers. Compositions useful in compressors for refrigeration comprise mixtures of oligomers according to the invention and refrigeration fluids, such as halocarbons, optionalfy containing appropriate functional fluid additives such as those mentioned above.

The invention is illustrated by the following non-limiting examples.

EXAMPLE 1 Preparation of bis (diphenylpphosphino) propanepalladiumdiacetate.

A solution of 1,3-bis (diphenylphosphino) propane (dppp) (5.55 g, 13.45 mmol) in toluene (75 cm 3) was added via a cannula to a filtered solution of palladium (II) acetate (3.00 g, 13.36 mmol) in toluene (200 cm 3) and the reaction mixture was stirred for 300 minutes, affording the product as an off-white precipitate. The liquor was removed via cannula filtration, the product dried in vacuo and isolated. Yield 7.30 g, 86 %.

EXAMPLE 2 Preparation of 1,3-bis (diphenylphosphino)-2,2-diethylpropane (dppp') A solution of n-butyl lithium (2.5 M in hexanes, 22.99 cm 3,57.5 mmol) was added dropwise via a syringe at 0 ° C to a stirred solution of diphenylphosphine (10 cm 3, 57.5 mmol) in THF (30 cm 3). The reaction mixture was allowed to warm to ambient temperature, and stirred for a further 90 minutes. This solution of lithium diphenyl phosphine was then added dropwise via cannula to a solution of 1,3-dibromo-2,2-diethylpropane (7.41 g, 28.73 mmol) in THF (70 cm 3). The reaction was heated to 60 ° C, and stirred at this temperature for 4 h., followed by stirring at ambient temperature for a further 15 h. The volatiles were removed in vacuo, affording a cream waxy solid. The product was extracted into pentane (300 cm 3) and filtered via canula. Concentration of the solution in vacuo and cooling to-30 ° C, afforded the product as white rock-like crystals, which were isolated by filtration and dried in vacuo. Yield 6.93 g, 51 %.

EXAMPLE 3 Preparation of (dppp') Pd (OAc) 2 The compound was prepared in an analogous fashion to Example 1, except using a filtered solution of palladium (II) acetate (0.96 g, 4.27 mmoi) in toluene (120 cm 3) and dppp',

as prepared in Example 2 (2.00 g, 4.27 mmol) in toluene (50 cm3). The product was isolated as a pale orange powder. Yield 2.10 g, 71 %.

EXAMPLE 4 Preparation of limonene derived catalyst, bis (4,8, dimethyl-2-phosphabicyclo [3,3,1] nonyl)- o-xylene palladium diacetate [(limphos) Pd (OAc) 2] (a) Preparation of bis (4,8, dimethyl-2-phosphabicyclo [3,3,1] nonyl)-o-xylene (limphos) A solution of 2-phospha-4,8-dimethyl-bicyclo (3.3.1) nonane (7.94 g, 46.62 mmol) in toluene (7.94 g) was added dropwise via syringe to a solution of a, a'-dibromo-o-xylene (6.15 g, 23.31 mmol) in degassed acetone (30 cm3) resulting in an exothermic reaction. The reaction mixture was stirred for 15 h at ambient temperature, yielding a turbid solution. The volatiles were removed in vacuo affording a white glassy solid which was suspended in degassed water (60 cm 3). A solution of sodium acetate trihydrate (31.72 g, 0.233 mol, 5 equiv. per P atom) in degassed water (70 cm 3) was added dropwise via cannula resulting in the formation of a white oil. The product was extracted into diethyl ether (3 x 70 cm 3), the ether layer dried over magnesium sulphate, and filtered into a pre-weighed flask. The volatiles were removed in vacuo affording limphos as a very pale yellow oil. Yield 6.82 g, 66 %.

(b) Preparation of (limphos) Pd (OAc) 2 A solution limphos (prepared as above, 6.82 g, 15.4 mmol) in dichloromethane (40 cm3) was added dropwise via cannula to an orange-red suspension of palladium (II) acetate (2.31 g, 10.27 mmol) in dichloromethane (200 cm 3) resulting in the formation of a very dark red solution. The reaction mixture was stirred at ambient temperature for 15 h.

The mixture was filtered via annula, and the volatiles removed in vacuo affording a dark brown-orange glassy solid. Pentane (200 cm 3) was added via canula, and attrition performed with a spatula. The liquor was removed via cannula filtration, and the product dried in vacuo and isolated as an orange-tan solid. Yield 6.50 g, 95 %.

EXAMPLE 5 Preparation of octene-carbon monoxide oligomer Methane sulphonic acid (63 ml, 0.971 mmol) was added via syringe to a solution of (dppp) Pd (OAc) 2, prepared as in Example 1, (0.2 g, 0.314 mmol) in 1-octene (143 cm 3, 0.91 mol) and methanol (189 cm 3,4.67 mol) and the reaction mixture stirred for 30 mins.

1,4-benzoquinone (oxidant) (0.17 g, 1.57 mmol) was added and the solution transferred to an autoclave. The solution was heated to 90 ° C, then pressured to 4 MPa with carbon monoxide, and stirred for 20 h. This resulted in the formation of a two-phase system, with a viscous lower phase containing the product. The lower phase was separated and heated on a rotary evaporator at 150 °C, affording the oligomeric product.

EXAMPLE 6 Preparation of octene-carbon monoxide oligomer The reaction was carried out as in Example 5, except using (dppp') Pd (OAc) 2s prepared according to Example 3 (0.21 g), methane sulphonic acid (63 ml), 1-octene (143 cm3) and methanol (189 cm'). Oxidant was not added. This resulted in the formation of a large lower phase [Weight gain = 16.0 g] which was worked up as in Example 5.

EXAMPLE 7 Preparation of Octene-carbon monoxide oligomer The reaction was carried out as in Example 6, except using (limphos) Pd (OAc) 2l as prepared in Example 4 (0.21 g), methane sulphonic acid (63 ml), 1-octene (143 cm 3) and methanol (189 cm3). Oxidant was not added. This resulted in the formation of a large lower phase which was worked up as in Example 5.

EXAMPLE 8 Preparation of Octene-carbon monoxide oligomer The reaction was carried out as in Example 6, except using (limphos) Pd (OAc) as prepared in Example 4 (0.84 g), methane sulphonic acid (252 ml), 1-octene (572 cm 3) and methanol (756 cm3). Oxidant was not added. This resulted in the formation of a large lower phase [weight gain = 40.6 g] which was worked up as in Example 5.

EXAMPLE 9 Preparation of Octene-carbon monoxide oligomer The reaction was carried out as in Example 6, except using (limphos) Pd (OAc) as prepared in Example 4 (0.42 g), methane sulphonic acid (172 ml), 1-octene (572 cm 3) and methanol (756 cm 3). Oxidant was not added. The autoclave run was carried out for 66 h.

This resulted in the formation of a large lower phase [Weight gain = 44.8 g] which was worked up as above. The oligomers were formed in a similar yield to those formed in Example 7, but had a lower residual palladium level.

EXAMPLE 10 Preparation of Decene-carbon monoxide oligomer The reaction was carried out as in Example 6, except using (limphos) Pd (OAc) 2, as prepared in Example 4 (0.42 g), methane sulphonic acid (172 ml), 1-decene (688 cm 3) and methanol (756 cm 3). Oxidant was not added. Reaction time was 44 h. This resulted in the formation of a very large lower phase [Weight gain = 38.0 g] which was worked up as in Example 5.

EXAMPLE 11 The suitability of the oligomers in lubricant compositions were tested using the following methods.

Viscometric properties for samples of polyketone oligomers prepared by the procedure of Examples 7 to 10 above are given in Table 1 below.

TABLE 1 SampleViscosityat40° C ViscosityatViscosityindex (mm2 s-') 100° C (mm2 s-') Example7 134 Example 8 140.6 Example10 177.5

The data in Table 1 shows that these materials have appropriate viscometric characteristics for use in lubricating fluids, that they can be synthesised reproducibly, and that the viscometric characteristics can be modified by appropriate selection of the olefine raw material.

A portion of oligomer from Example 7 was mixed with test materials including solvent neutral mineral oils and a standard additive package available as Lubrizol 9828A used in automotive engine crankcase lubricant formulations. The mixed samples were then examined after 2 hours and again after 24 hours to check that the components were fully miscible, i. e. that they had formed a single liquid phase.

Results are given below in Table 2.

TABLE 2 TestMaterialPercenttestPercentComments materialExample7 SolventNeutral ISO1005050Fully miscible mineral oil SolventNeutralISO5005050Fully miscibie mineraloil Automotiveadditivepackage2080Fully miscible (Lubrizol9828A) I

The results confirm that the oligomeric ketone prepared according to Example 7 is fully miscible with mineral oil and with standard lubricant additives.

A test fluid was prepared by adding 1 % of a standard antioxidant, lrganox L06 available from Ciba Geigy, to the oligomer from Example 7. Test pieces of standard elastomeric materiais were immersed in portions of the test fluid, and stored at 110° C for 7 days. The weight of the test pieces was measured at the beginning and end of the test, and the difference determined as a measure of the swelling tendency of the test fluid towards these materials.

Results are given below in Table 3.

TABLE 3 Material WeightGain(%) FluorocarbonViton 8015 0.66 SiliconeVMQ7501 7.26 NitrileNBR 7507 0.48 PolyacrylateACM7501 5.76 It was further observed that the test pieces did not degrade over the course of the test, keeping original shape and colour. These results indicate that the test fluid is expected to be compatible with standard elastomeric materials.