Highly active, recyclable catalyst for the manufacture of viscous, low molecular weight, CO-ethene-propene-based polyketone, base component for a new class of resins

Article abstract of DOI:10.1016/S0020-1693(01)00697-1

A highly active, recyclable homogeneous palladium(II) catalyst is described for the manufacture of viscous, low molecular weight CO-ethene-propene-based polyketone (Carilite Oligomer), used for the manufacture of a new class of resins (Carilite Resins). The catalyst is composed of palladium acetate, and a sulfonated diphosphine ligand, bdompp-S (1,3-bis(di-(2-methoxy, 5-sulfonatophenyl)phosphino)propane). In comparison with its non-sulfonated counterpart this catalyst not only exhibits a much more favourable partitioning coefficient in liquid-liquid separation of the polyketone product and solvent, but it also exhibits an approximately 2.5 times higher catalytic activity (up to 11.2 kg PK(g Pd)^-1h^-1) in the manufacture of PK-PE-30 (polyketone terpolymer built up of CO, ethene and propene in a molar ratio of 100:30:70). A variety of salts were found to exert a positive influence on the activity of the catalyst. Possible origins of this 'salt-effect' are briefly discussed. The bdompp-S ligand was synthesised by sulfonation of bdompp using either a boric acid-oleum mixture or sulfuric acid as the sulfonation reagent. The product was isolated either as sodium-salt (bdompp-S[Na]₄·nNa₂SO₄), by extraction with methanol after neutralisation, or, in acidic, hydrated form (bdompp-S[H]₄·nH₂O), via a new and highly efficient procedure, i.e. cooling the reaction mixture after dilution with water. The X-ray crystal structure of bdompp-S[H]₄·nH₂O is discussed.

Full text of DOI:10.1016/S0020-1693(01)00697-1

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Inorganica Chimica Acta 327 (2002) 147–159
Highly active, recyclable catalyst for the manufacture of viscous,
low molecular weight, CO–ethene–propene-based polyketone, base
component for a new class of resins
Wilhelmus P. Mul a,*, Hendrik Dirkzwager a, Antonius A. Broekhuis a,
Hero J. Heeres a,1, Adrianus J. van der Linden a, A. Guy Orpen b
a Shell Research and Technology Centre, PO Box 38000, 1030 BN Amsterdam, The Netherlands
b School of Chemistry, Uni6ersity of Bristol, Cantock’s Close, Bristol BS8 1TS, UK
Received 20 June 2001; accepted 17 September 2001
This paper is dedicated to Professor Kees Vrieze for our fruitful collaboration and his outstanding contributions to science
Abstract
A highly active, recyclable homogeneous palladium(II) catalyst is described for the manufacture of viscous, low molecular weight
CO–ethene–propene-based polyketone (Carilite Oligomer), used for the manufacture of a new class of resins (Carilite Resins). The
catalyst is composed of palladium acetate, and a sulfonated diphosphine ligand, bdompp-S (1,3-bis(di-(2-methoxy, 5-sulfona-
tophenyl)phosphino)propane). In comparison with its non-sulfonated counterpart this catalyst not only exhibits a much more
favourable partitioning coefficient in liquid–liquid separation of the polyketone product and solvent, but it also exhibits an
approximately 2.5 times higher catalytic activity (up to 11.2 kg PK (g Pd)−1 h−1) in the manufacture of PK-PE-30 (polyketone
terpolymer built up of CO, ethene and propene in a molar ratio of 100:30:70). A variety of salts were found to exert a positive
influence on the activity of the catalyst. Possible origins of this ‘salt-effect’ are briefly discussed. The bdompp-S ligand was syn-
thesised by sulfonation of bdompp using either a boric acid–oleum mixture or sulfuric acid as the sulfonation reagent. The product
was isolated either as sodium-salt (bdompp-S[Na]4·nNa2SO4), by extraction with methanol after neutralisation, or, in acidic,
hydrated form (bdompp-S[H]4·nH2O), via a new and highly efficient procedure, i.e. cooling the reaction mixture after dilution with
water. The X-ray crystal structure of bdompp-S[H]4·nH2O is discussed. © 2002 Elsevier Science B.V. All rights reserved.
Keywords: Palladium; Copolymerization; Homogeneous catalysis; Diphosphine; Sulfonation
1. Introduction
intermediate (Mn:1500–5000), referred to as Carilite
Oligomer, ranges from viscous flowing at room
temperature for the ethene-free types, to waxy or
melting solids at an ethene content of about 80 wt% (on
total olefin content). These intermediates are closely
related to Carilon Polymer, a family of semi-crystalline
thermoplastics [3].
Owing to the presence of the ketone functions, the
oligomer can be derivatized in various ways. Among
these, the Paal–Knorr reaction has been developed as
the basic curing chemistry. In this reaction two adjacent
ketone moieties and a primary amino group are
converted into a water-resistant pyrrole unit with the
liberation of water (Scheme 1). Carilite Oligomer can be
cured using a variety of di- or multi-functional amino-
Carilite Resins is a new class of polyketone-based
resins which are produced by alternating co- and ter-
polymerisation of carbon monoxide, ethene and pro-
pene, followed by chemical cross-linking (curing) [1,2].
Depending on the ratio between propene and ethene
incorporated in the polymer backbone, the product
consistency of the low molecular weight polyketone
* Corresponding author. Tel.: +31-20-630 2475; fax: +31-20-630
3034.
E-mail address: pim.w.p.mul@opc.shell.com (W.P. Mul).
1 Present address: Stratingh Institute, Department of Chemical
Engineering, Rijks Universiteit Groningen, Nijenborgh 4, 9747 AG
Groningen, The Netherlands.
0020-1693/02/$ - see front matter © 2002 Elsevier Science B.V. All rights reserved.
PII: S0020-1693(01)00697-1

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W.P. Mul et al. / Inorganica Chimica Acta 327 (2002) 147–159
Scheme 1. Carilite curing chemistry.
based curing agents [2]. Further, a method has been
developed in which Carilite is first converted into a
poly-amino-pyrrole by reaction with a non-symmetrical
di-amine at low temperature, followed by curing with
another equivalent of Carilite at high temperature [2c].
The use of these stable, water-based poly-amino-pyrrole
emulsions as intermediates prevents emission of volatile
ingredients during curing. The Carilite–polyamine ther-
moset system can be used in various applications like
foams, coatings, castings and adhesives. However, the
use as glue for the manufacture of various wood com-
posites is currently seen as the most promising outlet.
Like Carilon Polymer, CO–propene and CO–
ethene–propene-based Carilite Oligomer is manufac-
tured in an organic solvent using a homogeneous
palladium-based catalyst at a reaction temperature of
70–100 °C and pressures of typically up to 8.5 MPa
(Scheme 2). The catalyst selected for the manufacture
of Carilon Polymer at commercial scale is Pd-
(bdompp)X2 (bdompp=1,3-bis(di-(o-methoxyphenyl)-
phosphino)propane, X=weakly or non-coordinating
anion, e.g. triflate (OTf), tosylate (OTs), methylsul-
fonate (OMs), trifluoroacetate (TFA)). This catalyst is
not only more active than the most prominent member
of the first generation of CO–ethene copolymerization
grades, at a much higher rate than with Pd(dppp)X2
[3e].2,3
Initially, the catalyst applied in the production of
Carilon Polymer, Pd(bdompp)X2, was tested for the
manufacture of Carilite Oligomer. However, modest
performance of this catalyst, both in terms of activity
and recyclability, prompted us to search for an alterna-
tive catalyst system that would substantially lower the
contribution of the catalyst costs to the total manufac-
turing costs of the Carilite product. The use of a
sulfonated, water-soluble diphosphine ligand was antic-
ipated to lead to improved catalyst recycle efficiency [5].
In this paper, the synthesis and work-up of bdompp-S,
the tetra-sulfonated analogue of bdompp, are de-
scribed, as well as the performance (activity, recyclabil-
ity) of the palladium-based catalysts derived for the
manufacture of Carilite Oligomer.4 Recently, the manu-
facture of this catalyst and its excellent performance in
the copolymerisation of CO and ethene in water (with
rates up to 32 kg PK (g Pd)−1 h−1) was reported by
Sheldon and coworkers [5d].
2. Experimental
catalysts,
Pd(dppp)X2
(dppp=1,3-(diphenylphos-
2.1. General
phino)propane), but also produces co- and terpolymers
with a considerably higher molecular weight [3e,4].
All reactions were carried out under an inert atmo-
sphere (nitrogen), unless stated otherwise, using stan-
dard Schlenk techniques. Sulfuric acid (95–97%) was
purchased from Merck, boric acid from Aldrich and
27–33% sulfur trioxide solution in sulfuric acid from
Fluka. The solvents used were p.a. All chemicals were
2 Applied notation for perfectly alternating CO–a-olefin polyke-
tones: PK-M1M2-n, in which M1 and M2 are abbreviations for the
types of a-olefins incorporated in the co- or terpolymer chain (e.g.
M=ethene (E), propene (P)), and n, the molar monomer index
(n=(100·[M2]/([M1]+[M2])), the percentage of M2 (in mol%) on the
total amount of a-olefin incorporated in the polymer backbone. For
example, PK-E represents a copolymer build up of CO and ethene
while PK-EP-6 represents a terpolymer build up of CO, ethene and
propene in a molar ratio of 100:94:6.
This offers the advantage of producing PK-EP-6 with
Mn=52 000, one of the main commercial polyketone
3 The value for Mn was determined by GPC, and is given relative
to the PMMA standards.
4 Most results described in this paper have been published in
patent. See Ref. [1c].
Scheme 2. Synthesis of CO–ethene–propene-based polyketones.

W.P. Mul et al. / Inorganica Chimica Acta 327 (2002) 147–159
149
used without further purification. 1,3-Bis(di-(o-
methoxyphenyl)phosphino)no-propane (bdompp) was
synthesised according to literature procedures [6,7].
The 1H, 13C{1H}, 19F and 31P{1H} NMR spectra
were measured at room temperature (r.t.) in Varian 300
and 400 MHz spectrometers, operating at 300.1 and
active matter content was calculated to be 3694% and
the actual yield about 35%.
2.2.1. Spectroscopic data for bdompp-S[Na]4
1H NMR (D2O): l 7.71 (d, J=12.9 Hz, 4H, HAr),
7.55 (d, J=8.7 Hz, 4H, HAr), 6.9 (m, 4H, HAr), 3.63 (s,
12H, OCH3), 2.20 (m, 4H, CH2P), 1.44 (m, 2H,
CH2CH2P); 31P NMR (D2O): l −34.4 (s); 13C NMR
(D2O): l 163.2 (d, JCP=12.0 Hz, C5), 135.6 (s, C2),
129.9 (d, JCP=32.1 Hz, C3 or C6), (d, JCP=29.2 Hz,
C3 or C6), 124.4 (C4), 111.3 (d, JCP=51.2 Hz, C1),
56.0 (d, JCP=54.4 Hz, OCH3), 25.5 (br, CH2P), 21.5
(br, CH2CH2P). Anal. Found: C, 12.89; H, 2.81; P,
2.81; S, 15.42; Na, 17.92. Calc. for bdompp-S[Na]4·7.6
Na2SO4·27 H2O: C, 13.25; H, 2.94; P, 2.54; S, 15.18;
Na, 18.06%.
1
400.0 MHz for H, at 75.5 and 100.6 MHz for 13C, and
at 121.5 and 161.9 MHz, respectively, for 31P measure-
ments. Deuterated solvents were used as internal refer-
ence, and the 31P data are given in l units relative to
triphenylphosphine (−6 ppm). Elemental analysis was
performed at the Analytische Laboratorien, Lindar
(Germany). The sulfate concentration in the sulfonated
diphosphine products was determined with ion chro-
matography against a standard sulfate solution. IC-
conditions: DX100 (DIONEX), measured area
(analogous) 0–1000 mS; column: AG9 (guard column)
and AS4SC (separation column); eluent: 1.5 mM
HCO3− –1.2 mM CO32− demi-water. Detection was
achieved conductometrically.
The CO–ethene–propene terpolymerisation reac-
tions were carried out in a 350 ml, magnetically stirred
AISI 316 steel batch autoclave.
2.2. Synthesis of bdompp-S[Na]4
2.3. Preparation of a bdompp-S[Na]4-based catalyst
Orthoboric acid (3.2 g, 51.7 mmol) was dissolved in
30 ml of concentrated sulfuric acid (95–97%) and
stirred until a homogeneous solution was obtained.
After all boric acid had dissolved, 7.3 g (13.7 mmol) of
bdompp was added in small portions. The reaction
mixture was cooled to 0 °C and a solution of 30%
oleum (150 ml) was added drop wise, while the temper-
ature of the mixture was maintained between 0 and
5 °C.5 After the addition was complete, stirring was
continued at ambient temperature for 48 h. The mix-
ture was then hydrolysed by pouring it out on ice (400
g), neutralised by the addition of a 25 wt% solution of
sodium hydroxide in water, and concentrated by the
evaporation of water at 75 °C under vacuum until a
white suspension was formed. Methanol (750 ml) was
then added to the mixture, which was stirred for 15
min. The precipitate (Na2SO4) was removed by filtra-
tion. The product isolated after removal of the solvent
under vacuum still contained a significant amount of
Na2SO4. Therefore, a second extraction with methanol
was carried out. After filtration and removal of the
solvent under vacuum, a white product was obtained in
a yield of 12.6 g. Elemental analysis indicated the
product to consist of a mixture of bdompp-S[Na]4 and
hydrated Na2SO4. Based on this elemental analysis the
Palladium acetate (5.0 mg, 22 mmol) and bdompp-
S[Na]4·7.6Na2SO4·27H2O (65.9 mg, 25.2 mmol) were
dissolved in acetone (5 ml) at r.t., and then water (5 ml)
was added. After 1 h, trifluoroacetic acid (10.1 mg, 88
mmol) was added and a clear yellow solution was
obtained, which was used as such to catalyse the co-
polymerization reaction described below.
2.4. Polymerization reaction using
bdompp-S[Na]4-based catalyst
The reactor was charged with 129 ml of a MeOH–
H2O–HOAc–MeOAc mixture (45.4:29.5:5.3:19.6 v/v).
After purging the reactor with nitrogen, it was charged
with 60 g of propene and thereafter it was pressurised
with 7 bar (0.7 MPa) of hydrogen gas and 1 bar (0.1
MPa) of carbon monoxide. The reactor was subse-
quently heated to 89 °C and charged further with 30
bar (3.0 MPa) of a 80:20 v/v CO–ethene mixture gas to
give a total pressure of about 70 bar (6.9 MPa). After
stabilization of temperature and pressure, all the
bdompp-S[Na]4-based catalyst made according to the
procedure described above, was injected into the reac-
tor to start the reaction. The catalyst injection system
was flushed with 10 ml of acetone to ensure quantita-
tive catalyst injection. The reactor temperature in-
creased to 91 °C. The pressure was kept constant by
the continuous addition of 80:20 v/v CO–ethene mix-
ture gas. After 3 h the reaction was stopped. The flow
5 Reaction performed in accordance with the procedure(s) de-
scribed in: EP 632 047 (to Hoechst, 1994), EP 704 450 (to Hoechst,
1996).

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W.P. Mul et al. / Inorganica Chimica Acta 327 (2002) 147–159
of mixture gas was stopped by blocking the gas supply
and the reactor was cooled rapidly down to r.t., and
then the remaining gases were vented until atmospheric
pressure was obtained. The reaction mixture was col-
lected and the solvent mixture was removed under
reduced pressure at 70 °C. The isolated polymer was
weighed and analysed for molecular weight (GPC) and
ethene content (13C NMR). Reaction rate data were
calculated on the basis of gas flow uptake and on the
basis of average product weight and are summarised in
Table 3.
injected. Two recycles were carried out by this method.
The results of this experiment are labelled as Experi-
ment A in Table 5.
A variant of this procedure involves injecting addi-
tional fresh catalyst into the system compensating for
the loss of active catalyst during the recycle experi-
ments. Again two recycles were performed by this
method, 34 wt% of the fresh catalyst being added at the
start of each recycle. The results are labelled as Experi-
ment B in Table 5.
2.7. Synthesis of bdompp-S[H]4
2.5. Polymerization reaction using a bdompp-based
catalyst
The bdompp (22.5 g, 42.3 mmol) was added in small
portions to 110 ml of sulfuric acid and stirred for 24 h
at r.t. The reaction mixture was then poured in 500 ml
of water and after storage at 4 °C for 24 h, a white
precipitate was formed. After filtration, the white solid
was washed twice with 250 ml of methyl ethyl ketone.
After drying for 3 h at 80 °C under vacuum, 33.6 g of
bdompp-S[H]4·8H2O (90.0%) was obtained. No decom-
position was shown by bdompp-S[H]4·nH2O (e.g. oxi-
dation) when stored at ambient conditions for extended
periods (\1 year). The solubility of bdompp-
S[H]4·nH2O in water amounts to 280 g l−1 (20 °C) and
in methanol to 810 g l−1 (20 °C).
A catalyst was prepared by dissolving 5.0 mg (22
mmol) of palladium acetate and 12.5 mg (0.23 mmol) of
bdompp in 10 ml of acetone. After 1 h, 10.1 mg (88
mmol) of trifluoroacetic acid was added. The resulting
clear yellow liquid was used to start an oligomerisation
reaction according to the procedure described above,
using this catalyst in place of the bdompp-S[Na]4-based
catalyst. Polymerisation rate and product data are
given in Table 3.
2.6. Recycling experiments with catalyst
bdompp-S[Na]4
2.7.1. Spectroscopic data for bdompp-S[H]4
1H-NMR (D2O): l 7.86 (dd, J=8.8 Hz, J=2.0 Hz,
4H, H4), 7.74(dd, JPH=14.8 Hz, J=2.0 Hz, 4H, H6),
6.98 (dd, JPH=5.5 Hz, J=8.8 Hz, 4H, H3), 3.58 (s,
12H, OCH3), 2.91 (m, 4H, CH2P), 1.72 (m, 2H,
CH2CH2P); 31P-NMR (D2O): l −5.6; 13C-NMR
(D2O): l 163.5 (s, C2), 135.6 (d, JCP=12.6 Hz, C5),
134.9 (C4), 131.8 (C6), 112.9 (d, JCP=61.2 Hz, C3),
104.9 (d, JCP=140 Hz, C1), 56.8 (d, JCP=59.6 Hz,
OCH3), 19.0 (br, CH2ꢀP), 17.8 (br, CH2CH2P). Anal.
Found: C, 37.29; H, 5.21; P, 6.01; S, 12.67. Calc. for
bdompp-S[H]4·8H2O: C, 37.35; H, 4.98; P, 6.21; S,
12.87%; H2SO4-content (IC): 0.17 wt%.
First, a polymerization reaction was carried out as
described above for the bdompp-S[Na]4-based catalyst.
After 3 h the reaction was stopped by the steps taken in
the following order: first, the flow of the mixture gas
was stopped by blocking the gas supply; then the
reactor was cooled down to r.t. and vented until atmo-
spheric pressure was obtained. The reactor content was
subsequently transferred to a separation funnel. After
approximately 1 h the two phases were separated and
weighed. The top layer was used to charge the reactor,
the bottom layer was washed with the equilibrium
solvent
mixture
MeOH–H2O–HOAc–MeOAc
(45.5:29.5:5.3:19.6 v/v), with a volume of V(wash)=
V(reactor solvent) (129 ml)−V(top layer). This mix-
ture of the bottom layer and the wash-solvent were
allowed to settle and were separated after approxi-
mately 1 h. A second top layer and a bottom layer were
formed. Both layers were weighed. The reactor was
charged with both top layers. If necessary, the volume
was brought to the initial solvent volume of 129 ml.
The new bottom layer containing the polyketone
product was transferred to a rotavapor. The solvents
were removed at a reduced pressure of 1 mbar (0.1 kPa)
at 70 °C and the isolated polymer was analysed for
molecular weight and ethene content. The solvent mix-
ture in the reactor was used to perform the same
experiment again. However, this time no catalyst was
2.8. Preparation of a bdompp-S[H]4-based catalyst
Palladium acetate (5.0 mg, 22 mmol) and bdompp-
S[H]4.4H2O (21.8 mg, 23.6 mmol) were dissolved in
acetone (5 ml) at r.t., and then water (5 ml) was added.
After 1 h, trifluoroacetic acid (10.1 mg, 88 mmol) was
added and a clear yellow solution was obtained, which

W.P. Mul et al. / Inorganica Chimica Acta 327 (2002) 147–159
151
Table 1
MeOAc mixture (45.4:29.5:5.3:19.6, v/v). This mixture
was warmed in a centrifugation tube to 50 °C with
vigorous stirring. Subsequently, one of the selected
palladium catalysts was added in such an amount that
[Pd]mixture=500 ppm and stirring at 50 °C was contin-
ued for 1.5 h. The solution was cooled to ambient
temperature resulting in phase separation. Subse-
quently, the mixture was centrifuged for 30 min at 3000
rpm, resulting in the formation of two well-separated
layers. These layers were separated, weighed, and [Pd]
was determined by ICP-MS for both the top (solvent-
rich) and bottom (Carilite-rich) layers. The results are
given in Table 6.
Crystal data and structure refinement parameters for bdompp-
S[H]4·nH2O
Empirical formula
Formula weight
Crystal system
Space group (no.)
Unit cell dimensions
C31H53O26.5P2S4
1039.91
tetragonal
I4(1)/acd (no. 142)
,
a (A)
28.010(4)
24.021(5)
18846(5)
16
0.356
,
c (A)
3
,
V (A )
Z
Absorption coefficient (mm−1
Reflections collected
Independent reflections
Final R indices [I\2|(I)]
)
38481
3087 [Rint=0.1089]
R1=0.1339,
wR2=0.3723
1.498
2.11. Structure analysis of bdompp-S[H]4·nH2O
Goodness-of-fit on F2, S
Largest difference peak and hole
0.533 and −0.483
Crystal data and other details of the structure analy-
sis are presented in Table 1. A colourless crystal of
rod-like habit bdompp-S[H]4·nH2O of dimensions
0.13×0.13×0.50 mm was mounted at the end of a
glass fibre and held in place with silicone grease. All
diffraction measurements were made at −100 °C in a
Siemens SMART CCD area detector diffractometer,
using graphite monochromated Mo Ka X-radiation
−3
,
(e A
)
was used to catalyse the polymerization reaction de-
scribed below. In addition, catalyst solutions were pre-
pared to which 4.02, 6.12 or 8.00 mol NaOH per mole
bdompp-S[H]4 was added to neutralise the remained
sulfonic acids groups of the ligand. In one case sodium
sulfate (a constituent of the applied batch of bdomp-
S[Na]4) was added as well (see Table 4).
,
(u=0.71073 A). Diffracted intensities were measured in
a hemisphere of reciprocal space for 2qB45° by 0.3°
width ꢀ frames, a total of 1371 frames being measured.
No decay over the period of data collection was ob-
served. All data with I\ −3|(I) were retained for use
in structure refinement. An absorption and detector
correction was applied on the basis of 2787 symmetry
equivalent reflection intensities; effective transmission
coefficients were in the 1.00–0.691 range.
2.9. Polymerization reaction using bdompp-S[H]4-based
catalyst
The polymerization reaction was carried out as de-
scribed above for the bdompp-S[Na]4-based catalyst,
employing a hydrogen gas partial pressure of 4 bar
instead of 7 bar. The results are summarised in Table 4.
Refinement of the zwitterion indicated significant
disorder, notably manifested as large and highly an-
isotropic displacement parameters for the heavy atoms
(e.g. S(1) and S(2)). The other space groups investigated
did not give improved refinements. The water structure
is not well defined and the water oxygens in the refined
model have an occupancy sum equating to 10.5
molecules of water per molecule of zwitterion. The true
occupancy of water in the crystal is probably lower
than 10.5 since some of the oxygen sites are unrealisti-
cally close to one another (see below) and all show
large displacement parameters. This is in accord with
the other analytical data (which indicates an 8:1 H2O–
bdompp-S[H4] ratio). Attempts to refine a model with
lower occupancy oxygen positions led to significantly
worse residuals and so the model presented was re-
tained. Full occupancy oxygens are O(9, 10, 11, 13),
while O(12) has occupancy 0.25 and O(14) and O(15)
have occupancies of 0.5. All non-hydrogen atoms were
assigned anisotropic displacement parameters and
refined without positional constraints (except where
required by crystallographic symmetry). All hydrogen
atoms were constrained to idealised geometries and
2.10. Determination of partitioning coefficients
First, a sample of 129 g of Carilite Oligomer (PK-PE-
30, Mn=2470), synthesised with a (bdompp-S[Na]4-
based catalyst was purified (for residual Pd) by mixing
it with the solvent mixture consisting of 100 ml of
methanol and 70 ml of methyl ethyl ketone to which a
few drops of acetic acid were added and stirred
overnight at 60 °C. After cooling the solution to r.t.
150 ml of water was added and the resulting two phases
were separated. This procedure was repeated twice and
the remaining solvent was removed under vacuum af-
fording a sample of Carilite Oligomer (Mn=2560) con-
taining 2 ppm of palladium (ICP-MS). This sample was
used to determine the partitioning coefficients for Pd-
(bdompp)(TFA)2 and Pd(bdompp-S[Na]4)(TFA)2.
The partitioning coefficients were determined by mix-
ing Carilite Oligomer (95 g) with an exactly equal
amount of the solvent mixture applied to the polymer-
izations described above, MeOH–H2O–HOAc–

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W.P. Mul et al. / Inorganica Chimica Acta 327 (2002) 147–159
Scheme 3. Sulfonation of bdompp.
assigned fixed isotropic displacement parameter. Full-
matrix least-squares refinement of this model against F2
converged to final residual indices6 given in Table 1.
Final difference electron density maps showed no fea-
tures of chemical significance. Selected bond lengths
and bond angles are given in Table 2. Listings of the
final atomic positional parameters for the non-hydro-
gen atoms, the derived bond lengths and inter-bond
angles, and the anisotropic displacement parameters
and hydrogen atomic parameters, respectively, have
been deposited as a CIF file. All calculations were
carried out using programs of the SHELXTL package [8].
Complex neutral-atom scattering factors were taken
from Ref. [9].
under air, instead of under nitrogen. The applicability
of sulfuric acid as a sulfonation reagent for o-methoxy
substituted arylphosphines will stem from the electronic
properties of the o-methoxy group. In electrophilic
aromatic substitution reactions, the methoxy-group is a
moderately activating, ortho–para-directing group.
Isolation of bdompp-S was achieved via two different
procedures. After hydrolysis and neutralisation of the
reaction mixture followed by the removal of water
under vacuum, extraction of the residue with methanol
gave the product containing a varying, but substantial
amount of (hydrated) sodium sulfate (30–80 wt%;
based on elemental analysis).9 The ligand bdompp-
S[Na]4·xNa2SO4·yH2O, was isolated in a yield of 20–
1
35% and was characterised by H, 13C and 31P NMR
and elemental analysis. The presence of sodium sulfate
in the product was undesired. After several attempts, a
new, simple and efficient work up procedure was found.
After hydrolysis of the reaction mixture, storage at
5 °C or below resulted in the precipitation of a white
crystalline material.10 After filtration, washing with
methyl ethyl ketone and drying, the product was iso-
lated in acidic, hydrated form, bdompp-S[H]4·nH2O
(n=8; based on elemental analysis), typically in a yield
of 85–90%. The bis-zwitterionic product was character-
3. Results and discussion
3.1. Synthesis, isolation and characterization of
sulfonated bdompp
Bdompp was sulfonated using either a boric acid–
oleum mixture (Herrmann’s method [10]) or sulfuric
acid7 as the sulfonation reagent (Scheme 3). Complete
and selective conversion of bdompp into the tetra-sul-
fonated product (bdompp-S) took place, depending on
the reagent applied, within 4–24 h.8 Although the
reaction is highly exothermic and temperature excur-
sions of up to 60 °C were encountered, formation of
phosphine oxides or other side products was not ob-
served, even not when the reaction was performed
1
ised by H, 31P and 13C NMR spectroscopy (Fig. 1).
The occurrence of exclusive para-sulfonation (with re-
spect to the o-methoxy substituent) was confirmed by
H,H-COSY and C,H-COSY (PFG-HMQC techniques)
and by X-ray diffraction.11 The residual content of
sulfuric acid in the product did not generally exceed 0.2
wt% (based on sulfate analysis by ion chromato-
graphy).
6
wR2=[ꢀwZ2/ꢀwFo4]0.5; S=[ꢀwZ2/ (N−NV)] 0.5; R1=ꢀꢁ ꢁFoꢁ−
ꢁFcꢁ ꢁ /ꢀꢁFoꢁ; Z=Fo2−Fc2; N=NO+restraints; w=[|c2(Fo2)+
(gP)2]−1
;
|c2(Fo2)=variance in Fo2 due to counting statistics,
P=[max(Fo2,0)+2Fc2]/3.
9 This problem is often encountered when sulfonated phosphines
are isolated this way, but can be overcome by a proper choice of
extraction solvent. See Ref. [5d].
7 Sulfonation of bdompp by sulfuric acid was also reported by
Sheldon and coworkers [5d].
8 If the concentration of bdompp is too high (\25%) while em-
ploying sulfuric acid as the sulfonation reagent, the reaction does not
proceed completely. This is probably due to a gradual lowering of the
acid concentration because of the generation of 1 mol of H2O per mol
of the sulfonic acid group generated. The concentration of H2SO4
must be higher than 92%; otherwise the sulfonation proceeds very
slowly and incompletely or not at all. Incomplete conversion of
bdompp can be overcome by the addition of some oleum (30%).
10 Also at room temperature, the reaction mixture is over-saturated
and the product crystallizes upon standing. However, cooling of the
reaction mixture accelerates this process and improves the yield.
11 The 31P NMR resonances of bdompp-S[H]4 (−5.6 ppm),
bdompp-S[Na]4 (−34.4 ppm), bdompp (−36.6 ppm) and proto-
nated bdompp, bdompp-[H]2·2OTf (−4.5 ppm), clearly indicate the
presence of bdompp-S[H]4 in zwitterionic form, containing proto-
nated phosphorus atoms.

W.P. Mul et al. / Inorganica Chimica Acta 327 (2002) 147–159
153
Fig. 1. Zwitterionic bdompp-S[H]4.
Further study revealed that bdompp-S[H]4·nH2O pre-
cipitates from water–sulfuric acid mixtures over a
broad range of ratios (in high yield over the range of
3:1–10:1 v/v). Its limited solubility in water–sulfuric
acid mixtures (ꢀ0.5 wt% at 4 °C) was quite unex-
pected regarding its high solubility both in pure water
(28 wt% at 20 °C) and in concentrated sulfuric acid
(\25 wt% at 20 °C). A possible explanation for this
phenomenon is that over the given ratio, water–sulfuric
acid mixtures are much more polar than the concen-
trated sulfuric acid or pure water as such, due to the
high degree of dissociation of sulfuric acid (pK1 1.92) in
water. As a result, the bis-zwitterionic, overall neutral,
Fig. 2. Molecular structure of bdompp-S[H]4 showing atom labelling
scheme. All hydrogen atoms have been omitted for clarity.
diphosphine bdompp-S[H]4 is a relatively apolar species
in these highly polar mixtures and hence exhibits a
limited solubility. Alternatively, it might be due to
‘salting-out’ of bdompp-S[H]4, with H3O+·HSO3− be-
ing the salt. This new, simple and unprecedented isola-
tion procedure might be applicable to other sulfonated
(di)phosphines as well.
Table 2
,
Selected bond lengths (A) and bond angles (°) for bdompp-
S[H]4·nH2O
3.2. X-ray crystal structure
Bond lengths
The structure of zwitterionic [H2{(2,5-C6H3(OMe)-
(SO3)}2PHCH2CH2CH2PH{(2,5-C6H3(OMe) ꢀ (SO3)}2]·
nH2O, bdompp-S[H]4·nH2O, is shown in Fig. 2. The
crystal structure consists of [H2{2,5-C6H3(OMe)-
S(1)ꢀO(2)
S(1)ꢀO(1)
S(1)ꢀO(3)
S(1)ꢀC(5)
S(2)ꢀO(5)
S(2)ꢀO(7)
S(2)ꢀO(6)
S(2)ꢀC(12)
P(1)ꢀC(3)
P(1)ꢀC(10)
P(1)ꢀC(2)
C(1)ꢀC(2)
1.32(2)
1.37(2)
1.392(12)
1.745(13)
1.269(14)
1.38(2)
1.39(2)
1.63(2)
1.764(10)
1.766(14)
1.783(12)
1.516(14)
(SO3)}2PHCH2CH2CH2PH{(2,5
-
C6H3(OMe)(SO3)]
molecules and water molecules. No hydrogen atoms
were located in the X-ray analysis, as a result of the
rather poor quality diffraction data obtained.12 Crystals
did not show any signs of loss of water from the
structure during the lifetime of the experiment. Selected
bond lengths and bond angles are given in Table 2.
Molecules of bdompp-S[H4] lie at positions of the
crystallographic twofold rotational symmetry (C2) and
therefore there is one crystallographically unique phos-
phorus in the structure. The P(CH2)3P chain therefore
has an extended conformation as is expected for a
(CH2)3 chain linking the two bulky centres [11]. Al-
though the hydrogen at the tertiary phosphonium cen-
tre was not directly located its presence is clearly
implied by the PꢀC and CꢀPꢀC angles [12] which are
small and large, respectively, compared with the tertiary
diarylphosphine species. In other respects the in-
tramolecular geometry is unexceptional and not very
Bond angles
O(2)ꢀS(1)ꢀO(1)
O(2)ꢀS(1)ꢀO(3)
O(1)ꢀS(1)ꢀO(3)
O(2)ꢀS(1)ꢀC(5)
O(1)ꢀS(1)ꢀC(5)
O(3)ꢀS(1)ꢀC(5)
O(5)ꢀS(2)ꢀO(7)
O(5)ꢀS(2)ꢀO(6)
O(7)ꢀS(2)ꢀO(6)
O(5)ꢀS(2)ꢀC(12)
O(7)ꢀS(2)ꢀC(12)
O(6)ꢀS(2)ꢀC(12)
C(3)ꢀP(1)ꢀC(10)
C(3)ꢀP(1)ꢀC(2)
C(10)ꢀP(1)ꢀC(2)
C(2)ꢀC(1)ꢀC(2) a
110(2)
106.2(12)
117(2)
107.0(11)
106.8(8)
108.5(7)
107(2)
116.1(13)
109.3(14)
107.1(10)
107.2(10)
109(2)
114.2(5)
110.7(5)
107.6(7)
107.2(13)
12 Attempts to improve data quality by collection at lower (and
room) temperature proved fruitless. All crystals examined gave simi-
lar low quality diffraction patterns with no useful intensity beyond
2q=45°.
a Symmetry transformations used to generate equivalent atoms:
−y+5/4, −x+5/4, −z+1/4.

154
W.P. Mul et al. / Inorganica Chimica Acta 327 (2002) 147–159
Fig. 3. Packing diagram of the structure of bdompp-S[H]4·nH2O viewed down the c axis.
*-marked contacts are more likely to be artefacts rather
than real contacts given the disorder problems.)
The unique full occupancy SO3···water contact
reliably determined because of the disorder problems
noted above.
The presence of a proton at each phosphorus implies
that two of the four sulfonic acid groups per molecule
of bdompp-S[H4] are deprotonated (i.e. one of the two
unique SO3 groups in the crystal). It is not clear from
the intramolecular geometry of bdompp-S[H4] as to
which sulfonate oxygen carries the remaining proton.
The shortest interaction between full occupancy oxy-
,
O(1)···O(9) 2.52 A may be tentatively assigned as that
involving the unique proton on the sulfonato groups.
There are no short O···O contacts between zwitterions.
Thus the zwitterions are heavily solvated by water in
the solid state, presumably mimicking the solution be-
haviour of bdompp-S[H4]. As may be seen in Fig. 3 the
water dominated regions of the structure are arranged
in channels around the fourfold axes of the crystal
structure, while the hydrophobic parts of bdompp-
S[H4] are located in the intervening regions.
,
gens is O(1)···O(9) 2.51 A. The other O···O contacts of
,
B3.1 A involving SO3 group oxygen atoms are:
,
,
O(2)···O(10) 2.87 A, O(3)···O(15) 2.15 A*; O(5)···O(13)
3.01 A; O(6)···O(11) 2.77 A, O(7)···O(9) 2.92 A,
O(7)···O(10) 3.04 A. There appears to be little or no
intramolecular hydrogen bonding of significance. Thus
the shortest H···O contact involving the phosphonium
,
,
,
,
3.3. Catalyst performance
,
hydrogen is 2.78 A [O(8)···H(1)]. The water oxygens
(O9–15) show hydrogen bonded (or artificial) contacts
In comparison with Carilon Polymer, Carilite
Oligomer is characterised by a much higher propene
content. Whereas commercial grades of Carilon Poly-
mer typically contain about 6 mol% of propene on total
olefin content, Carilite Oligomer contains 50–100 mol%
of propene depending on its application. The target of
,
between themselves B3.1 A as follows: O(9)..O(11)%
1.83 A*, O10)···O(13)% 2.86 A, O(11)···O(15) 2.47 A*,
O(12)···O(15) 2.39 A*, O(13)···O(14) 2.706 A,
O(14)···O(14)’’ 2.08 A*, O(15)···O(15) 2.89 A*. (The
,
,
,
,
,
,
,

W.P. Mul et al. / Inorganica Chimica Acta 327 (2002) 147–159
155
the current study was the manufacture of PK-PE-30
Pd(bdompp-S[Na]4)(OAc)2+2 HTFA“
Pd(bdompp-S[Na]4(TFA)2+2 HOAc
with Mn=2400, one of the main Carilite Oligomer
grades containing 30 mol% of ethene and 70 mol% of
propene.1 Synthesis of this material instead of Carilon
Polymer is achieved by adjusting the propene–ethene
ratio in the reaction mixture and the reaction tempera-
ture. As the rate of termination/propagation is concur-
rently changed, much lower molecular weights are
obtained at higher propene content and similar reaction
temperature. No fundamental study was undertaken to
map the effect of temperature on the rate, the molecu-
lar weight and the content of propene. Increasing the
reaction temperature while maintaining the CO–
ethene–propene partial pressure ratio, generally leads
to the manufacture of lower molecular weight materials
at a higher reaction rate.
In the present study the catalysts were first tested at
91 °C under standard catalyst screening conditions.
The reaction conditions were later optimised to obtain
the desired product composition. The CO–ethene–
propene polymerisation experiments were carried out
using an ‘equilibrium’ mixture of MeOH–H2O–
HOAc–MeOAc (45.5:29.5:5.3:19.6 v/v) as the solvent.
This particular solvent mixture was selected for two
reasons. Addition of acetic acid in methanol has been
found to stabilise the catalyst, while addition of water
improves the degree of product–solvent separation,
thus facilitating product work-up and catalyst recy-
cling. Polymerisation was started by injecting a solution
of the catalyst into the reactor at process conditions
and continued for 3 h. The pressure was kept constant
with a constant supply of an 80:20 CO–ethene mixture.
Propene was only supplied before the catalyst was
injected. After the reaction was stopped, the solvent
was removed under vacuum and the product analysed
(GPC, 13C NMR, viscosity).
(4)
It should be noted that Pd(bdompp-S[Na]4)(TFA)2
may also be viewed as Pd(bdompp-S[Na]2)·2NaTFA, as
the coordination behaviour of the TFA-anions is de-
pendent on the solvent. In the applied polar reaction
solvent, counterions like TFA−, and RSO3− are essen-
tially non-coordinating as they exhibit virtually no in-
fluence on the performance of the catalyst.
Application of the ligand in protonated (zwitterionic)
form, bdompp-S[H]4·nH2O, required a modified cata-
lyst preparation procedure. Upon mixing Pd(OAc)2 and
bdompp-S[H]4, ligand complexation and acetate anion
exchange take place simultaneously (Eq. (5)), affording
Pd(bdompp-S[H]2), a formally bis-zwitterionic species.
The counter cations (H+) were exchanged by the addi-
tion of sodium hydroxide (Eq. (6)).
bdompp-S[H]4+Pd(OAc)2“
Pd(bdompp-S[H]2)+2 HOAc
Pd(bdompp-S[H]2)+2 NaOH“
Pd(bdompp-S[Na]2)+2 H2O
(5)
(6)
3.3.2. Performance of the catalysts
Table 3 illustrates the higher catalytic activity ob-
tained with the bdompp-S[Na]4-based catalyst in com-
parison with the non-sulfonated catalyst, Pd(bdompp)-
(TFA)2. The average activity for Pd(bdompp)(TFA)2
and Pd(bdompp-S[Na]4(TFA)2 over a period of 3 h
amounted to 4.2 and 9.9 kg PK (g Pd)−1 h−1, respec-
tively. The bdompp-S[Na]4-based catalyst is not only
more active than Pd(bdompp)(TFA)2, but it also pro-
duces Carilite terpolymer with an approximately 15%
higher molecular weight, and a somewhat higher
propene content. Both the molecular weight and the
propene content of the terpolymer were controlled by
the reaction temperature. So, PK-PE-30 with Mn=
2400 can be produced at a somewhat higher reaction
temperature employing Pd(bdomppS[Na]4(TFA)2 as the
catalyst in comparison with Pd(bdompp)(TFA)2. As the
reaction rate increases with temperature, the effective
rate improvement by using Pd(bdompp-S[Na]4(TFA)2
instead of Pd(bdompp)(TFA)2 will be even larger than
the factor of about 2.5 found at 91 °C (Table 3).
The rate of polymerisation was not constant during
the course of the reaction, e.g. it dropped by about 20%
over 3 h when applying Pd(bdompp-S[Na]4(TFA)2 as
the catalyst. This is most likely caused by physical
factors. First, the properties of the solvent changed
considerably as at the end of the run, the solvent
contains 20–50 wt% of the product. Secondly, the
composition of the gas cap changed during the run as
gas consumption (CO–propene–ethene in a molar ratio
of 50:35:15) and gas supply (CO–ethene in a molar
3.3.1. Preparation of the catalysts
The bdompp-based catalyst was prepared by dissolv-
ing Pd(OAc)2 and bdompp (1.05 equiv.) in acetone (Eq.
(1)), followed by the exchange of acetate anions for
weakly coordinating anions by addition of a fourfold
excess of trifluoroacetic acid (Eq. (2)).
bdompp+Pd(OAc)2“Pd(bdompp)(OAc)2
(1)
Pd(bdompp)(OAc)2+2 HTFA“
Pd(bdompp)(TFA)2+2 HOAc
(2)
The bdompp-S[Na]4-based catalyst was prepared in a
similar way (Eqs. (3) and (4)), using a water–acetone
mixture as the solvent.
bdompp-S[Na]4+Pd(OAc)2“
Pd(bdompp-S[Na]4)(OAc)2
(3)

156
W.P. Mul et al. / Inorganica Chimica Acta 327 (2002) 147–159
Table 3
Manufacture of Carilite Oligomer—catalyst performance a
Property
bdompp
bdompp-S(Na)4
bdompp-S(H)4
b
Initial rate (kg PK (g Pd)−1 h−1
)
6.1
4.2
29.7
4.2
14.3
11.5
70.0
9.9
3280
33
End of run rate (kg PK (g Pd)−1 h−1
)
b
Yield (g)
43.0
6.1
3590
43
Average rate (kg PK (g Pd)−1 h−1
Mn (Da)
)
c
2870
Mol% ethene built in
37
24
1,3-propyl (% of total propyl groups) d
32
29
a Polymerization conditions: catalyst: Pd(OAc)2–diphosphine ligand–trifluoroacetic acid (in a ratio of 1:1.05:4); solvent: MeOH–H2O–HOAc–
MeOAc (45.4:29.5:5.3:19.6, v/v); [Pd]=18 ppm; T=91 °C; t=3 h; initial partial pressures: P(H )=7 bar, P(ethene)=5 bar, P(propene)=30 bar,
2
P
(CO)=21 bar; Ptotal=70 bar (at 91 °C), kept constant by feeding CO–ethene (80:20).
b Based on gas uptake.
c Based on polymer yield.
d Based on total olefin content.
ratio of 80:20) were not identical. During the run the
gas cap became less rich in olefins, while the reaction
rate is about first-order in olefin and more rich in CO,
while the rate is practically zero-order in CO at higher
PCO (\15 bar).
of the products was far above the target (Table 3). For
that reason the majority of further experiments with
Pd(bdompp-S[H]2) were carried out at a higher temper-
ature (100 °C; Table 4). Under further identical poly-
merisation conditions, ‘virgin’ Pd(bdompp-S[H]2)
catalyst (no NaOH was added) exhibited an activity of
6.7 kg PK (g Pd)−1 h−1, while the molecular weight of
the product dropped from Mn=3600 to about 2900. As
the average catalytic activity for Pd(bdompp-S[H]2) was
lower than that experienced with Pd(bdompp-
S[Na]4)(TFA)2, a series of experiments was carried out
in which the two remaining sulfonic acid groups of
Pd(bdompp-S[H]2) were neutralised by the addition of
(an excess) sodium hydroxide (Eq. (6)). In one case
some sodium sulfate was also added (a major con-
stituent of the first batches of bdompp-S[Na]4 isolated).
The results of these experiments are listed in Table 4. A
clear trend is observed between the amount of sodium
hydroxide added and the catalyst activity. The average
catalytic activity over 3 h increased to a value of 10.1
kg PK (g Pd)−1 h−1 by addition of 8 mol of sodium
hydroxide per mole of Pd(bdompp-S[H]2) and even
further to 11.2 kg PK (g Pd)−1 h−1 by an extra addi-
tion of sodium sulfate. It should be noted that excess of
NaOH (\2 mol per mole Pd(bdompp-S[H]2)4 is con-
verted into NaOAc in the acetic acid containing reac-
tion solvent mixture (or into NaTFA, as trifluoroacetic
acid was generally a constituent of the catalyst mix-
ture). Besides an increase in activity, a decrease in the
Analysis of oligomers by 13C NMR revealed the
backbone of the Carilite Oligomer to consist of a
random combination of mainly ꢀCH2CH2C(O)- and
ꢀCH2CH(CH3)C(O)-units. Further, a substantial frac-
tion of propene was build in the terpolymer in the
1,3-mode (see Fig. 4), typically in about 25–35%.13
A
variety of end-groups were detected, n-propyl, iso-pro-
pyl, n-propenyl and iso-propenyl being the dominating
ones. Only small amounts of ester end-groups were
observed. This indicates b-H elimination to be the
major termination process and initiation to take place
predominantly via the Pd-hydride cycle [3d]. The posi-
tive influence of hydrogen on the polymerisation rate is
thought to emerge from the conversion of the relatively
slowly initiating L2Pd2+-species, present at the start of
the polymerisation and formed after termination via
protonolysis (Eq. (7)) into a directly propagating
L2PdH+-species according to Eq. (8) [13].14
[L2Pd(CH2CH2C(O)R]++H+“
L2Pd2+ +CH3CH2C(O)R
(7)
(8)
L2Pd2+ +H2 X L2PdH++H+
The bdompp-S[H]4-based catalyst, Pd(bdompp-
S[H]2), prepared according to Eq. (5), exhibits a consid-
erably lower activity than its sodium counterpart,
prepared from bdompp-S[Na]4. The molecular weight
13 Incorporation of propene in the 1,3-mode during perfectly alter-
nating CO–propene or CO–propene–ethene copolymerization is a
well-known phenomenon. See, e.g. Ref. [3b].
14 Protonolysis occurs via the intermediacy of a palladium enolate
complex. See Ref. [13].
Fig. 4. Incorporation modes of propene.

W.P. Mul et al. / Inorganica Chimica Acta 327 (2002) 147–159
157
Table 4
Influence of sodium salts on catalyst performance a
Entry
NaOH
(mol/mol ligand)
Yield (g)
Average rate
Mn
Mw/Mn
ethene=built in
(mol% on total olefin content)
(kg PK (g Pd)−1 h−1
)
1
2
3
4
5
None
4.02
6.12
8.00
47
54
63
71
79
6.7
7.7
8.9
10.1
11.2
2910
2460
2300
2260
2230
1.93
1.88
1.85
1.88
1.89
38
36
31
31
30
6.12+17.3 Na2SO4
a Polymerization conditions: catalyst: Pd(OAc)2–bdompp-S(H)4–trifluoroacetic acid (in a ratio of 1:1.05:4); solvent: MeOH–H2O–HOAc–
MeOAc (45.4:29.5:5.3:19.6, v/v); [Pd]=18 ppm; T=100 °C; t=3 h; initial partial pressures: P(H )=4 bar, P(ethene)=5 bar, P(propene)=30 bar,
2
P(CO)=21 bar; Ptotal=69 bar (at 100 °C), kept constant by feeding CO–ethene (80:20).
molecular weight of the product and a decrease of the
amount of ethene built in into the oligomer backbone is
also observed on increasing the amount of sodium salt.
This salt effect was found to be a general phenomenon.
Addition of a variety of other salts (including, e.g.
NaOAc, NaOTf, Na3PO4, LiOTf, CaSO4, NiSO4 and
FeSO4) induces a similar effect on rate, Mn and ethene
incorporation [1c].
breaking up self-association of the sulfonated, water
soluble ligands applied [16], or, if the manufacture of
the oligomers occurs under two-phase conditions [17],15
from increasing the polarity difference between the
solvent-rich and product-rich phases leading to resi-
dence of a larger part of the running polar catalyst
species, [Pd(bdompp-S)R] (R represents the growing
polyketone chain), in the solvent-phase. Clearly, further
study is required to elucidate the underlying chemical
and/or physical aspects of this intriguing salt effect.
It was a pleasant surprise to note that the bdompp-S-
based palladium catalyst not only exhibits a firmly
improved recyclability (vide infra), but also a more
than doubled activity for the manufacture of Carilite
Oligomer in comparison with the initially tested cata-
lyst, Pd(bdompp)(TFA)2. The second noteworthy as-
pect is the positive influence exerted by salts on the
performance of the catalyst. An activity increase of up
to 70% was observed, while the amount of ethene built
in the oligomer backbone decreased substantially (by
up to 30%). Also the molecular weight dropped, to
below Mn=2400. The salt effect might both be chemi-
cal or physical in origin. It is not simply related to the
conversion of the ꢀSO3H-units of the bdompp-S ligand
into ꢀSO3Na (Eq. (6)), otherwise addition of more than
2 mol of NaOH per mole Pd(bdompp-S[H]2 would not
have exerted a further positive effect. In fact, the upper
limit of the salt effect might not even have been reached
in the limited series of experiments described here
(Table 4). The fact that salts also containing non-basic,
non-coordinating anions (e.g. NaOTf, LiOTf), exert a
positive influence, might point to the occurrence of a
cation-effect.
3.3.3. Recyclability of the catalysts
Two series of recycling experiments were conducted
(Table 5). After the polymerisation run was stopped,
the reaction mixture was allowed to separate at room
temperature in a product-rich bottom layer and a sol-
vent-rich, product-poor, top layer. After the layers were
separated and the bottom layer was washed with a new
aliquot of solvent, the combined top layers were used in
a next polymerisation experiment.16 In series A, no
additional supply of fresh catalyst solution was applied
in the recycles. The product yield declined by about
34% after two recycles. In series B, about 34% of extra
catalyst was added at the start of each next cycle in
order to compensate for the loss of active catalyst loss
via the bottom phase. In this series, the product yield in
the first and second recycle was about the same as in
the initial run, illustrating that the amount of fresh
catalyst added was sufficient to compensate for the loss
of catalytic activity.
Alkali and alkaline-earth metals have been reported
to enhance the rate and the position of equilibrium in
the migratory insertion of CO in metal–alkyl bonds
[14], one of the steps in the catalytic propagation cycle
leading to perfectly alternating polyketones [3d]. How-
ever, CO-insertion is not expected to be the rate-deter-
mining step in perfectly alternating CO–olefin
copolymerizations. It is imaginable that cations assist
the opening of five- and/or six-membered palladacycles,
crucial intermediates in the propagation cycle [15]. On
the other hand, the salt effect might emerge from
15 Recently, experimental evidence has been provided from polymer
end-groups analysis for the occurrence of running palladium-based
polyketone catalyst species, [Pd(bdompp)R]+, in two different states
under slurry process conditions. Depending on the length of the
copolymer chain, R, the catalyst is either dissol6ed during CO–ethene
copolymerization (at the shorter chains, up to 13–20 [CH2CH2C(O)]-
units) or polyketone-supported (at the longer chains, above 13–20
[CH2CH2C(O)]-units). See Ref. [17].
16 The composition of the solvent of the combined top layers was
roughly the same as that of the initially applied solvent mixture; the
water content was slightly higher and the MeOAc content slightly
lower.

158
W.P. Mul et al. / Inorganica Chimica Acta 327 (2002) 147–159
Table 5
Efficiency of catalyst recycling a
Property
Experiment A b
Experiment B c
Initial
1st recycle
2nd recycle
Initial
1st recycle
2nd recycle
d
Initial rate (kg PK (g Pd)−1 h−1
)
10.4
8.5
7.5
6.9
5.3
6.7
4.8
3.4
4.8
11.0
8.8
7.9
9.9
7.1
8.0
9.0
6.4
8.2
End of run rate (kg PK (g Pd)−1 h−1
)
d
Average rate (kg PK (g Pd)−1 h−1
Yield (g)
)
e
56.4
50.3
35.8
58.0
58.9
59.9
a Polymerization conditions: catalyst: Pd(OAc)2–bdompp-S(Na)4–trifluoroacetic acid (in a ratio of 1:1.05:4); solvent: MeOH–H2O–HOAc–
MeOAc (45.4:29.5:5.3:19.6, v/v), [Pd]=18 ppm (initially); T=91 °C; t=3 h; initial partial pressures: P(H )=4 bar, P(ethene)=5 bar, P(propene)
=
2
30 bar, P(CO)=21 bar; Ptotal=65–67 bar (at 91 °C), kept constant by feeding CO–ethene (80:20).
b No fresh catalyst was added.
c In each recycle 34 wt% of fresh catalyst was added.
d Based on gas uptake.
e Based on polymer yield of bottom layer.
Table 6
a
Partitioning coefficients for L2Pd(TFA)2
Entry
L2
Catalyst
(mg)
Weight
mixture
(g)
Bottom layer
(g)
Top layer
(g)
[Pd]bottom
(ppm)
[Pd]top
(ppm)
K
Pd mass
balance
(%)
[Pd]top/[Pd]bottom
(ppm/ppm)
1
2
3
bdompp
bdompp-S
bdompp-S
45
51
78
11.11
8.43
13.05
9.22
7.09
10.87
1.65
1.27
2.11
513
24
20
467
2541
2563
0.9
106
128
99
81
86
a Over a two-phase Carilite-solvent mixture; Carilite PK-PE-30; Mn=2560; solvent: MeOH–H2O–HOAc–MeOAc (ratio 45.4:29.5:5.3:19.6, v/v).
lyst recycling efficiency. It is expected that this
efficiency can be improved by introducing a dedicated
post-treatment procedure, inducing termination of
those catalyst species still containing a polymer chain.
On bases of the Pd-content analyses of the vari-
ous phases, the partitioning coefficient for bdompp-
S[Na]4-based catalyst in series B (K value, defined as
[Pd]top-layer/[Pd]bottom-layer (ppm/ppm)) was calculated to
be 4.7 (initial cycle), 3.8 (1st cycle) and 4.7 (2nd cycle),
respectively. Although these values are significantly
higher than those found for the non-sulfonated Pd-
(bdompp)(TFA)2, for which K values of about 0.3 were
found in separate recycling experiments, the values were
lower than expected.
Therefore the actual partitioning coefficients of Pd-
(bdompp)(TFA)2 and Pd(bdompp-S[Na]4)(TFA)2 over
a two-phase Carilite-solvent mixture were determined in
separate series of experiments (Table 6). Using the
‘equilibrium’ mixture employed in the polymerization
experiments described above, the partitioning coeffi-
cient K for Pd(bdompp)(TFA)2 was found to be 0.9,
while the partitioning coefficient for Pd(bdompp-
S[Na]4)(TFA)2 was found to be \100. The lower recy-
cling efficiency observed under actual polymerisation
conditions (series A and B) is attributed to the occur-
rence of part of the catalyst species in non-terminated
form, [Pd(bdompp-S)R] (R=terpolymer chain), during
recycling. Depending on the length of the terpolymer
chain attached to the catalytic palladium centre, these
species will be ‘attached’ to the more apolar Carilite-
phase via their polymeric tail, and hence diminish cata-
4. Concluding remarks
A new, highly active homogeneous palladium-based
catalyst has been developed for the manufacture of low
molecular weight CO–ethene–propene-based polyke-
tone (Carilite Oligomer). By virtue of the development
of a simple, highly efficient and environmentally
friendly recipe for the production of the sulfonated
diphosphine constituent in the catalyst recipe, bdompp-
S[H]4, this new catalyst has become the preferred candi-
date for the manufacture of Carilite Oligomer.
In comparison with its non-sulfonated counterpart
this catalyst not only exhibits a much more favourable
partitioning coefficient in liquid–liquid separation of
product and solvent, but it also exhibits an approxi-
mately 2.5 times higher catalytic activity. An economic
evaluation showed that application of this new catalyst
reduces the contribution of the catalyst costs to the
total manufacturing costs of Carilite Oligomer by a
factor of about 7.5 when compared with the non-sul-
fonated catalyst applied first.

W.P. Mul et al. / Inorganica Chimica Acta 327 (2002) 147–159
159
perfectly alternating copolymerization of ethene and carbon
monoxide, see:
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