CATALYST PREPARATION

Abstract: A catalyst suitable for the polymerization of ethylenically unsaturated compounds. A bidentate ligand with general formula (I) in which X = P, As, Sb, n = 0 or 1, R1, R2 = alkyl, alkoxy, aryloxy, cycloalkyl or a substituted or non-substituted (cyclo)aliphatic, (cyclo)olefinic or aromatic group with 1-24 C-atoms, or R1 and R2 may form together a substituted or non-substituted cycloaliphatic, cyclo-olefinic or aromatic group, R3, R4, R7, R8 = H, alkyl, alkoxy, aryloxy, cycloalkyl or a substituted or non-substituted (cyclo)aliphatic, (cyclo)olefinic or aromatic group with 1-24 C-atoms, and if n = 1:R5 and/or R6 = H, alkyl, alkoxy, aryloxy, cycloalkyl or a substituted or non-substituted (cyclo)aliphatic, (cyclo)olefinic or aromatic group with 1-24 C-atoms, and C' and C'' together with R3 and R6 may form a substituted or non-substituted (cyclo)aliphatic, (cyclo)olefinic or aromatic group, R4 and R5 being absent in this case, or C' and C'' may form an olefinic bond, R4 and R5 being absent in this case, with a source of cations of a metal of group 8, 9 or 10 of the Periodic Table of Elements and an acid having a pKa of less than 4.

Description: CATALYST PREPARATION The invention relates to of a catalyst which is preparable by combining a bidentate ligand, a source of cations and an acid. The invention also relates to a process for the polymerization and co-polymerisation of ethylenically unsaturated compounds, using the catalyst. In WO 96/23010 of Du Pont/U.N. Carolina, a process for the polymerization of olefins is described. This process uses catalysts comprising bisimine Pd(II) and Ni(II) complexes in dichloromethane or toluene. Since such bisimine complexes are only stable at relatively low temperatures, the olefin polymerization process has to be operated at such temperatures and hence the turnover (moles of product per mole of catalyst) of the latter process is rather low. The present inventors have now found a catalyst that is much more stable at higher temperatures. Therefore a process for the polymerization or co-polymerisation of ethylenically unsaturated compounds, using this catalyst, can be carried out at higher temperatures. For this reason the turnover of the polymerization process when using the catalyst of the present invention can be much higher than that of the process according to WO 96/23010. Moreover, the present catalyst can be synthesized without exclusion of air while the bisimine catalysts according to WO 96/23010 are prepared from a very air- sensitive (bisimine) PdMe2 complex. The present invention therefore relates to a catalyst suitable for the polymerization of ethylenically unsaturated compounds, which is preparable by combining a bidentate ligand with the general formula: in which X = P, As, Sb, n = 0 or 1, R ] _, R2 = alkyl, alkoxy, aryloxy, cycloalkyl or a substituted or non-substituted (cyclo) aliphatic, (cyclo) olefinic or aromatic group with 1-24 C-atoms, or R ] _ and R 2 may form together a substituted or non- substituted cycloaliphatic, cyclo-olefinic or aromatic group R3, R4 , R7 , Rg = H, alkyl, alkoxy, aryloxy, cycloalkyl or a substituted or non-substituted (cyclo) aliphatic, (cyclo) olefinic or aromatic group with 1-24 C-atoms, and if n = XR5 and/or Rg = H, alkyl, alkoxy, aryloxy, cycloalkyl or a substituted or non-substituted (cyclo) aliphatic, (cyclo) olefinic or aromatic group with 1-24 C-atoms, and C and C" together with R3 and Rg may form a substituted or non-substituted (cyclo) aliphatic, (cyclo) olefinic or aromatic group, R4 and R5 being absent in this case, or C and C" may form an olefinic bond, R4 and R5 being absent in this case, with a source of cations of a metal of group 8, 9 or 10 of the Periodic Table of Elements and an acid having a pKa of less than 4. In the above ligand the moiety X can be phosphorus, arsenic or antimony, phosphorus being the preferred element to be incorporated into the ligand constituting part of the present catalyst. The present catalyst comprises a metal of group 8, 9 or 10 of the Periodic Table of Elements, as shown on Technology, edited by C. Morris, Academic Press Inc., San Diego (1992) . These groups include the metals: Fe, Ru, Os, Co, Rh, Ir, Ni, Pd, Pt . Palladium is the preferred metal of the present polymerization catalyst. As source of palladium cations, conveniently a palladium salt is used. Suitable palladium salts are mineral salts, such as palladium sulphate, palladium nitrate and palladium phosphate. Other suitable palladium salts are salts of sulphonic acids, such as methylsulphonic acid, trifluoromethane- sulphonic acid and p-toluenesulphonic acid and salts of carboxylic acids, such as acetic acid and propionic acid, halo-acetic acids, for example trifluoro- and trichloroacetic acid, oxalic acid and citric acid. As source of palladium cations use may also be made of the metal in its elemental form, or in a zero valent state, e.g. in complex form such as in palladium- dibenzylacetone or palladium-tetrakis-tri-phenyl- phosphine . These sources are generally applied in combination with a protonic acid, thus yielding the palladium cations in situ. Palladium salts of carboxylic acids are preferred sources of palladium cations, in particular palladium acetate . Suitable palladium organometallic complexes can also be used, e.g. cyclo-octadiene palladium chloro-methyl . The present catalyst can be formed by combining the above ligand and the above source of cations with an anion source, derived from an acid having a pKa < 4 in a solvent. As a source of anions such acids comprise H 2 As0 4 , HF, HJ0 , H3PO3, H3PO4, H3PO7, HNO3, H 2 Se0 3 , H 2 Te0 3 , H 2 S0 , CH 2 CLCOOH, CHCl 2 COOH, CCI3COOH, CH BrCOOH, CH 2 .COHCH (COOH) 3 , COOH . CH : CH . COOH (trans ) , CH OH.COOH, COOH. CH:CH. COOH (cis) , COOH. CHOH . CH 2 . COOH, COOH . CH 2 . COOH, CH . CHOH. COOH, H.COOH, COOH. COOH, COOH . CHOH . CHOH . COOH, CHgH5.CO.NH.CH2.COOH, CgH 4 . (COOH)2, CgH 2 (OH) . (NO2) 3, CgH4.OH.COOH, CgH4.NH2.SO3H, C5H4N4O3, p-toluenesulphonic acid and CF3SO3H, the latter two being preferred. Alternatively salts of these acids can be used . As an example a catalyst can be prepared by the reaction between cyclo-octadiene palladium chloro-methyl and silver trifluoromethylsulphonate . Suitable solvents for the catalyst preparation process according to the invention are hydrocarbons, alcohols, ethers and ketones or mixtures thereof. Examples of suitable solvents are toluene, pentane, CH2CI2, CI1CI3, dioxane, water, 2-ethylhexanol, ethylene glycol, glycerol, the dimethylether of ethylene glycol (digly e) and diethylether, the preferred solvents being toluene, methanol or CH2CI2. In the bidentate ligand moiety of the present catalyst the groups R^ and R2 may be identical or different from each other. Prefer+ably they are identical and both O-methoxyphenyl groups. Advantageously R]_ and R2 form together a cyclo-octyl group. The group Rg in the bidentate ligand can be H or any organic group with 1-24 C-atoms. Advantageously Rg is chosen such that the moiety (Rg-N=) is a di-isopropyl- aniline group. The present invention also relates to a process for the polymerization of ethylenically unsaturated hydrocarbons using the above catalyst. In the present specification, unless otherwise stated, the term "polymerization" includes "oligomerization" and "dimerization" . Ethylenically unsaturated compounds to be used as starting material in the polymerization process according to the invention include unsaturated hydrocarbons and unsaturated compounds, comprising besides hydrogen and carbon atoms at least one other atom in their molecules such as an oxygen or nitrogen atom. Olefins, in particular mono-olefins are preferred starting materials, for example ethene, propene, butenes, pentenes, hexenes, heptenes, octenes, dicyclopentadiene, 4-methylpentene, 4-pentenoic acid or its esters, norbornene, functionalized alkenes, possibly containing heteroatoms and mixtures thereof. They may be applied together with other unsaturated hydrocarbons, for example cyclic olefins such as cyclopentene and cyclohexene, diolefins such as butadiene, 1, 4-pentadiene and 1,5- hexadiene, olefins substituted by aromatic groups such as styrene, allylbenzene, p-methylstyrene and alpha- methylstyrene and acetylenically unsaturated compounds such as acetylene, phenylacetylene and isopropenylacetylene . The invention is of particular interest for the preparation of co-polymers whereby one of the monomers is a lower olefin, in particular ethene and propene and at least one of the other monomers contains a functional group such as a hydroxy, cyano, anhydride or ester group. Examples of suitable monomers of this category are 3-buten-l-ol, 5-hexen-l-ol, 10-undecen-l-ol, alkyl esters of acrylic or methacrylic acid such as methylacrylate, methylmethacrylate and ethylacrylate, vinyl esters such as vinylacetate and vinylpropionate and anhydrides such as the anhydride of 5-norbornene-2, 3-dicarboxylic acid. As a suitable co-monomer CO can be applied. If desired, the polymerization process according to the invention may be carried out in the presence of a suitable solvent. Various solvents such as hydrocarbons, alcohols, ethers, esters and ketones may be used, including an excess of one of the monomers, provided this monomer is in the liquid phase under the reaction conditions of the process. Surprisingly it has been found that the use of different reaction solvents results in the formation of polymer products having different molecular weights. Generally the use of an apolar solvent results in the formation of polymers of relatively high molecular weights, whereas the presence of a polar solvent will result in the formation of oligomers, i.e. reaction products containing from two to twenty monomer units. For example, in the event of a reaction solvent, substantially consisting of polar compounds such as water or di- or trihydric alcohols, e.g. ethylene glycol and glycerol, predominantly oligomeric products are formed. On the other hand with a reaction solvent, substantially consisting of relatively apolar compounds, such as the dimethylether of ethylene glycol (diglyme) or diethylether, polymer products of higher molecular weight can be formed. In the process according to the invention only catalytic amounts of the catalyst system are required. Usually the amount of catalyst is in the range of 10 ~ 1 to 10 "~' mole per mole of ethylenically unsaturated compound to be polymerized. Preferably, the catalyst is applied in an amount between 10 ~ 2 and 10 ~ 6 anc ι most preferably in the range of 10 ~ 3 to 10 ~ 5 mole per mole of ethylenically unsaturated compound to be polymerized. It will be appreciated that the utility of the products obtained will depend, inter alia, on the molecular weight of the products. Oligomeric products may find use e.g. as starting materials in the production of plasticizers, lubricants and surfactants. The products of higher molecular weight are of interest as thermoplastics and may be applied for films, sheets, packaging materials and the like. The process of the invention may be carried out at moderate reaction conditions, both in the event that in a predominantly apolar reaction medium products of relatively high molecular weight are prepared and in the event that in a polar reaction medium oligomers are produced. Reaction temperatures are usually in the range of 10 to 200 °C, temperatures in the range of 25 to 130 °C being preferred. Usually superatmospheric reaction pressures are applied, for example in the range of 1 to 100 bar, pressures outside the indicated range not being precluded. Preferably a pressure in the range of 2 to 60 bar is applied. The catalyst system according to the invention may suitably be prepared separately, by combining the source of metal cations or a precursor thereof and the other components as defined above in the presence of a suitable solvent, before supplying the monomer (s) to be (co)- polymerized. It is also possible to prepare the catalyst in situ by introducing the catalyst components into the reactor and at the same time adding the monomer (s) and any other compound to be present in the reaction medium. For preparing the catalyst system, the molar amounts of metal compound, the ligand and acid as defined above may be substantially equal. Usually an excess of the acid is preferred, for example up to 10, preferably up to 5 equivalents of acid per gram atom of metal. The invention is illustrated by the following, non- limiting examples. Example 1 Iminophosphine ligands "L" were synthesized from the corresponding amine and aldehyde as shown in Scheme 1 : Scheme 1 The groups R^, R^ and R3 of the ligands L for different catalysts are shown in Table 1 : Table 1 Ph = phenyl Me = methyl iPr = i-propyl Catalysts were formed by the combination of the bidentate ligands L, Pd(OOC.CH3)2 and a non-coordinating anion of a weak acid, i.e. p-toluenesulphonic acid (p-TosOH) or CF3SO3H, via an anion exchange reaction. Example 2 Procedure for the synthesis of ligand Lh To 1.0 g (2,86 mmol) 2- [bis (2-methoxyphenyl) - phosphino] benzaldehyde in 50 ml toluene was added 0.51 g (2.86 mmol) 2,6 di-isopropylaniline and a catalytic amount p-toluene-sulphonic acid. The solution was refluxed for 4h under Dean-Stark conditions. The solvent was evaporated to yield a yellow oil, which was crystallized from CH3OH. Yield: 1.27 g (87%) Anal. Calc. for C33H 3 0 P: C 77.78 H 7.12 N 2.75 P 6.08 Found: C 77.61 H 7.22 N 2.91 P 5.93 The synthesis of ligands La up to and including Lg is carried out along an analogous route. Example 3 With the aid of the catalysts which have been discussed in Example 1 and Table 1 oligomerization reactions were performed under 20 bar ethylene, at a temperature of 100 °C and in 50 ml solvent CH30H. The catalyst comprised 0.1 mmol Pd (OOC .CH3) 2 , 0.11 mmol ligand and 0.21 mmol TosOH. The product ratio was determined by gas chromatography . Higher olefins were obtained, as shown in Table 2 in which the sum of the percentages of the moles of Cg to C_g approximates 100%. Table 2 Ligands in ethylene oligomerisation Turnover number (moles ethylene converted per mole catalyst) Table 2 shows the product ratio for various iminophosphine ligands. Increasing the steric bulk at the nitrogen donor site, resulted in higher molecular weights (compare Experiments 1 and 2 with 3 and 6 with 8) . Furthermore, when more steric bulk on the phosphorus site was introduced (in case of o-methoxy analog Lh) the molecular weight was increased again (compare Experiments 3, 4 and 8) . Remarkably, the activity (T.O. from 250 to 1100) was increased dramatically, by replacing the two phenyl groups on phosphorus by o-methoxyphenyl groups (Table 2, experiment 8) . The catalytic activity was furthermore influenced by electronic effects on the imino donor site; in particular electron releasing groups enhanced the rate. For instance by changing R^ from chlorine to methoxy (Le-Lg) resulted in the increase of T.O. from 150 to 800. Furthermore, the isomerization increased at higher temperatures (Table 3) as well as the amount of branched products (Table 4) . Decrease of the steric hindrance in the ligand, resulted also in more branched products (compare Lc and Lh) . Table 3 Product ratio dependence on temperature Table 4 Linearity of C -C^2 Fine tuning of the reaction could be achieved by changing solvent and anion. Typical results are summarized in Table 5. By going from MeOH to CH2CI2 the activity slightly decreased. However, when CF3SO3- was used as counter ion in solvent CH2CI2 (Exp. 3) , the turnover number increased considerably. Table 5 Example 4 Using similar reaction conditions as applied in Example 3, a Pd-catalyst comprising the ligand N-{2-[bis- (2-methoxyphenyl) hosphino] benzylidene} -2, 5- (diiso- propyl) benzene-amine gave in 1.5 h in ethyleneglycol a turnover number of about 1100 mol/mol Pd. The product ratio was : Cg:25%, C 8 :27%, C 10 :23%, C 1 :17%, C 14 :5%, Cχg:3%. The linearity was Cg:95%, Cg:92%, C o : 86%- The experiment with 40 bar ethylene in methanol gave the following results: Cg:26%, Cg:26%, C 10 :20%, C 12 :14%, C 14 :9%, C]_g:5%. The turnover was about 1350 mol/mol Pd. The number of 1-olefins was also about the same: Cg:39%, Cg:30%, C 10 :21%. In conclusion, a new metal based catalyst system for ethylene oligomerization has been developed. Remarkable features are the excellent stability in solvents at high temperatures, the formation of Cg-C g oligomers at these temperatures and the possibility to tune the oligomer selectivity by the iminophosphine ligands.

Claims: C L I M S 1. A catalyst obtainable by combining a bidentate ligand with the general formula: in which X = P, As, Sb, n = 0 or 1, R]_, R2 = alkyl, alkoxy, aryloxy, cycloalkyl or a substituted or non-substituted (cyclo) aliphatic, (cyclo) olefinic or aromatic group with 1-24 C-atoms, or R and R2 may form together a substituted or non- substituted cycloaliphatic, cyclo-olefinic or aromatic group, R3, R4 , R7 , Rg = H, alkyl, alkoxy, aryloxy, cycloalkyl or a substituted or non-substituted (cyclo) aliphatic, (cyclo) olefinic or aromatic group with 1-24 C-atoms, and if n = 1 : R5 and/or Rg = H, alkyl, alkoxy, aryloxy, cycloalkyl or a substituted or non-substituted (cyclo) aliphatic, (cyclo) olefinic or aromatic group with 1-24 C-atoms, and C and C" together with R3 and Rg may form a substituted or non-substituted (cyclo) aliphatic, (cyclo) olefinic or aromatic group, R4 and R5 being absent in this case, or C and C" may form an olefinic bond, R4 and R5 being absent in this case, with a source of cations of a metal of group 8, 9 or 10 of the Periodic Table of Elements and an acid having a pKa of less than 4. 2. A catalyst as claimed in claim 1, characterized in that X = P. 3. A catalyst as claimed in claim 1 or 2, characterized in that the metal of group 8, 9 or 10 of the Periodic Table of Elements is Pd. 4. A catalyst as claimed in any one of claims 1-3, characterized in that the acid having a pKa of less than 4 is p-toluenesulphonic acid or CF3SO3H. 5. A catalyst as claimed in any one of claims 1-4, characterized in that in the bidentate ligand R and R 2 are o-methoxyphenyl groups . 6. A catalyst as claimed in any one of claims 1-5, characterized in that in the bidentate ligand (=N-Rg) is a di-isopropylaniline group. 7. A catalyst as claimed in any one of claims 1-6, characterized in that the solvent is toluene, methanol or CH 2 C1 2 . 8. A process for the polymerization or co-polymerisation of ethylenically unsaturated organic compounds, characterized in that a catalyst is used as claimed in claim any one of claims 1-7. 9. A process as claimed in claim 8, characterized in that the ethylenically unsaturated compound is an α- olefin or a mixture of two or more α-olefins or a mixture of at least one α-olefin and at least one functionalized olefin . 10. A process as claimed in claim 8 or 9, characterized in that the ratio between the molar amount of the ethylenically unsaturated compound (s) and the amount of the catalyst is in the range of from 10:1 to 10^:1. 11. A process as claimed in any one of claims 8-10, characterized in that the polymerization is carried out in a solvent, at a temperature in the range of from 10 to 200 °C and at a pressure of 1-100 bar.

Inventors: DRENT EIT, FERINGA BERNARD LUCAS, VAN DEN BEUKEN ESTHER, DRENT, EIT, FERINGA, BERNARD, LUCAS, VAN DEN BEUKEN, ESTHER
Applicants: SHELL INT RESEARCH, SHELL INTERNATIONALE RESEARCH MAATSCHAPPIJ B.V.
Application year: 1998
Main classification: B01J31
IPC codes: B01J31, C08F4, C08F10