Polymerization of carbon monoxide and olefin with acid catalyst

Linear alternating copolymers of carbon monoxide and at least one ethylenically unsaturated hydrocarbon are produced in the presence of novel catalysts formed from a Group VIII metal compound, an anion of a non-hydrohalogenic acid having a pKa above about 2 but below about 4, and certain bidentate ligands of phosphorus.

It is known that reaction of carbon monoxide with one or more ethylenically 
unsaturated hydrocarbons in the presence of a suitable catalyst results in 
the production of linear alternating polymer known as polyketones. 
Polymerization of carbon monoxide with at least one ethylenically 
unsaturated hydrocarbon, e.g., ethylene or mixtures of ethylene and 
propylene in the presence of a catalyst prepared from certain Group VIII 
metal compounds, e.g., palladium compounds, an anion of a 
non-hydrohalogenic acid having a pKa less than about 6 and certain 
bidentate ligands of phosphorus, arsenic or antimony results in the 
formation of a linear alternating polymer having units of the formula 
##STR1## 
where A is the moiety obtained by polymerization through the ethylenic 
unsaturation of the ethylenically unsaturated hydrocarbon. In the case of 
such polymerization of carbon monoxide and ethylene, the polymeric units 
are of the formula 
##STR2## 
In general, the polymerization follows a typical temperature-reaction rate 
relationship. For example, in the case of polymerizations employing 
catalyst compositions formed in part from non-hydrohalogenic acids having 
a pKa less than 2, a conventionally preferred class of acids, a higher 
reaction temperature leads to a higher reaction rate with lower reaction 
rates being observed at lower temperatures. It would be of advantage to 
provide for polymerizations which observe faster reaction rates at 
relatively low temperatures as well as catalyst compositions which are 
more active at such lower reaction temperatures. 
SUMMARY OF THE INVENTION 
The present invention relates to the polymerization of carbon monoxide and 
at least one ethylenically unsaturated hydrocarbon in the presence of 
novel catalyst compositions which exhibit greater activity at relatively 
low reaction temperatures than is observed at higher reaction 
temperatures. More particularly, the invention relates to a process for 
the polymerization of carbon monoxide and at least one ethylenically 
unsaturated hydrocarbon in the presence of a catalyst composition formed 
from a palladium compound, an anion of a non-hydrohalogenic acid having a 
pKa more than about 2 but less than about 4 and certain bidentate 
hydrocarbyl phosphine ligands.

DESCRIPTION OF THE INVENTION 
The present invention relates to a polymerization process employing a 
catalyst composition formed from a palladium compound, an anion of a 
non-hydrohalogenic acid having a pKa more than about 2 but less than about 
4, and bidentate hydrocarbyl phosphine ligands, under typical 
polymerization pressures but under controlled reaction temperature. 
The acid from which the anion catalyst component is derived is preferably 
an oxygen-containing acid having a pKa, measured in water at 18.degree. 
C., which is above about 2 but below about 4. The acid is an inorganic 
acid such as phosphoric acid, arsenic acid, nitrous acid or selenious acid 
but is preferably an organic monocarboxylic acid or dicarboxylic acid such 
as tartaric acid, 2,5-dihydroxybenzoic acid, acetoacetic acid, bromacetic 
acid, 2-chlorobenzoic acid, .alpha.-chlorobutyric acid, cyanoacetic acid, 
(2-cyanophenoxy)acetic acid, chloroacetic acid, glycolic acid, 
2-gluorobenzoic acid, and 2-furan-carboxylic acid. Best results are 
obtained using the anion of an acid selected from phosphoric acid, 
tartaric acid and 2,5-dihydroxybenzoic acid. In the catalyst compositions 
of the invention, the anion is provided in a quantity from about 0.5 to 
about 200 equivalents per gram-atom of palladium (as the compound), 
preferably from about 1 to about 100 equivalents per gram-atom of 
palladium. 
The method of providing the anion is not critical. The anion is provided as 
the acid or alternatively is provided as a metal salt of the acid. 
Preferred salts for provision of the anion are non-noble transition metal 
salts, i.e., salts of Group IB-Group VIIB of the Periodic Table of 
Elements. Particularly useful as a non-noble transition metal salt is a 
copper salt. 
The palladium compound is preferably a palladium carboxylate. In part for 
reasons of availability, palladium acetate is a particularly preferred 
palladium compound although palladium propionate and palladium octanoate 
are also suitable. In one modification, the palladium moiety and the anion 
of the acid are provided as a single compound, e.g., palladium tartarate, 
palladium chloroacetate or palladium ortho-chlorobenzoate. 
The bidentate phosphorus ligand employed in the catalyst composition is a 
ligand of the formula 
##STR3## 
wherein R.sup.1, R.sup.2, R.sup.3 and R.sup.4 independently are 
hydrocarbyl of from 1 to 20 carbon atoms inclusive but preferably are aryl 
of from 6 to 10 carbon atoms inclusive, more preferably phenyl, R is a 
divalent hydrocarbyl bridging group of from 2 to 10 carbon atoms inclusive 
and with from 2 to 4, preferably 3 carbon atoms in the 
phosphorus-phosphorus bridge. The preferred R group is the trimethylene 
--CH.sub.2 --CH.sub.2 --CH.sub.2 -- group. Illustrative R.sup.1, R.sup.2, 
R.sup.3 and R.sup.4 groups include phenyl, dimethylphenyl, ethylphenyl, 
tolyl, and n-octylphenyl. Illustrative of the bidentate ligands containing 
the preferred trimethylene R group are 1,3-bis(diphenylphosphino)propane, 
1,3-bis[di(4-methylphenyl)-phosphino]propane, 
1,3-bis[di(4-isopropylphenyl)phosphino]propane and 
1,3-bis[di(2,4-dimethylphenyl)phosphino]propane. The ligand 
1,3-bis(diphenyl-phosphino)propane is a particularly preferred bidentate 
ligand. 
In the catalyst compositions, the bidentate ligand is present in an amount 
from about 0.1 mol to about 3 mol per mol of palladium compound, 
preferably from about 0.75 mol to about 2 mol per mol of palladium 
compound. 
The ethylenically unsaturated hydrocarbons useful in the process of the 
invention are hydrocarbons from 2 to 20 carbon atoms inclusive and 
preferably from 2 to 10 carbon atoms inclusive. The hydrocarbons are 
wholly aliphatic, particularly ethylene and other .alpha.-olefins such as 
propylene, butene-1, octene-1 and dodecene-1 or incorporate aryl 
substituents on a carbon atom of the ethylenic unsaturation. Illustrative 
of this latter class of unsaturated hydrocarbons are styrene, 
p-methylstyrene and p-ethylstyrene. The preferred ethylenically 
unsaturated hydrocarbons for polymerization with carbon monoxide are 
ethylene or mixtures of ethylene and a second .alpha.-olefin, particularly 
propylene. 
In the reaction mixture to be polymerized, the molar ratio of ethylenically 
unsaturated hydrocarbon to carbon monoxide is from about 10:1 to about 1:5 
with molar ratios from about 5:1 to about 1:2 bein preferred. In the 
embodiments where more than one ethylenically unsaturated hydrocarbon is 
employed in the production of terpolymers, for example, terpolymers of 
carbon monoxide, ethylene and a second unsaturated hydrocarbon, the molar 
ratio of ethylene to second ethylenically unsaturated hydrocarbon is from 
about 400:1 to about 5:1, preferably from about 100:1 to about 10:1. 
The quantity of catalyst composition to be utilized will vary, but amounts 
of catalyst composition containing from about 1.times.10.sup.-7 to about 
1.times.10.sup.-3 gram-atom of palladium per mol of unsaturated 
hydrocarbon are suitable with amounts from about 1.times.10.sup.-6 to 
about 1.times.10.sup.-4 gram-atom of palladium per mole of unsaturated 
hydrocarbon being particularly useful. 
The polymerization reaction is conducted under conditions of elevated 
temperature and pressure. Care must be taken not to employ too high a 
reaction temperature since catalyst activity decreases if too high a 
temperature is employed. Temperatures should be below about 115.degree. C. 
with the range from abut 20.degree. C. to about 110.degree. C. being 
suitable. A preferred temperature range is from about 30.degree. C. to 
about 100.degree. C. The reaction pressure is not critical and pressures 
from about 1 bar to about 200 bar are satisfactory, but preferably from 
about 20 bar to about 200 bar. 
In some embodiments of the process of the invention, it is useful to add a 
quinone to further enhance the activity of the catalyst. Suitable quinones 
are quinones of from 6 to 20 carbon atoms inclusive and include 
benzoquinones, naphthaquinones and anthraquinones. Benzoquinones are 
preferred, especially 1,4-benzoquinone. The use of quinone is optional, 
and amounts of quinone up to about 10,000 mol per gram-atom of palladium 
are useful with an amount up to about 5,000 mol per gram-atom of palladium 
being preferred. 
The reaction is conducted in the liquid phase in the presence of a diluent, 
preferably a lower alkanol of up to 10 carbon atoms. Methanol is a 
particularly useful diluent. The method of contacting the reactants is not 
critical and is effected by shaking, stirring or other conventional means. 
Subsequent to reaction, the polymer product is recovered by conventional 
methods as by filtration or decantation. The product may contain residues 
of the catalyst which may be removed, if desired, by contact with a 
solvent selective for the residue. 
The polyketone products of the polymerization process of the invention are 
known materials of known utility as premium thermoplastics. They are 
formed into sheets or molded into shaped articles finding application as 
parts in the auto industry or as containers for beverages and food. 
The invention will now be further illustrated by means of the following 
illustrative embodiments and comparative examples which are illustrative 
only and are not to be construed as limiting. 
COMATIVE EXAMPLE I 
To a stirred autoclave of 300 ml capacity was charged a catalyst solution 
containing 50 ml of methanol, 0.1 mmol of palladium acetate, 2 mmol of 
acetic acid (pKa=4.75) and 0.15 mmol of 1,3-bis(diphenylphosphino)propane. 
After removal of any air present by evacuation of the autoclave, ethylene 
was introduced under pressure until a pressure of 30 bar had been reached, 
followed by addition of carbon monoxide until a pressure of 60 bar was 
obtained. The contents of the autoclave were brought to 135.degree. C. and 
maintained for 15 hours, after which the autoclave was cooled to room 
temperature and the pressure released. A very small amount of polymeric 
material was obtained. 
COMATIVE EXAMPLE II 
The procedure of Comparative Example II was repeated except that the 
reaction temperature was 90.degree. C. instead of 135.degree. C. and the 
reaction time was 5 hours instead of 15 hours. Again, no more than a trace 
of polymer was obtained. 
COMATIVE EXAMPLE III 
The procedure Comparative Example I was repeated except that phosphoric 
acid (pKa=2.12) was employed instead of acetic acid and the reaction time 
was 5 hours instead of 15 hours. After the reaction was terminated by 
cooling the autoclave and releasing the pressure in the autoclave, the 
polymer formed was removed by filtration, washed with methanol and dried 
in vacuo. A copolymer product, 0.5 g, was obtained. The calculated 
reaction rate was 10 g of copolymer/g Pd/hr. 
ILLUSTRATIVE EMBODIMENT I 
The procedure of Comparative Example III was repeated except that the 
reaction temperature was 90.degree. C. instead of 135.degree. C. and the 
reaction time was 2.5 hours instead of 5 hours. The product, 11 g of 
copolymer was obtained. The calculated reaction rate was 440 g of 
copolymer/g Pd/hr. 
ILLUSTRATIVE EMBODIMENT II 
The procedure of Comparative Example III was obtained except that the 
catalyst solution contained tartaric acid (pKa=2.98) instead of phosphoric 
acid, the reaction temperature was 90.degree. C. instead of 135.degree. C. 
and the reaction time was 2 hours instead of 5 hours. 9.3 g of copolymer 
was obtained at a calculated reaction rate of 465 g of copolymer/g Pd/hr. 
ILLUSTRATIVE EMBODIMENT III 
The procedure of Comparative Example III was repeated except that the 
catalyst solution contained 2,5-dihydroxybenzoic acid (pKa=2.97) instead 
of phosphoric acid and the reaction temperature was 90.degree. C. instead 
of 135.degree. C. The copolymer product, 6.4 g, was obtained at a 
calculated reaction rate of 128 g of copolymer/g Pd/hr. 
The carbon monoxide/ethylene copolymers prepared according to Illustrative 
Embodiments I-III had a melting point of 257.degree. C. From .sup.13 C-NMR 
analysis it was determined that the polymers had a linear alternating 
structure consisting of units of the formula 
##STR4## 
ILLUSTRATIVE EMBODIMENT IV 
When the procedure of Illustrative Embodiment I is repeated in the 
additional presence of a minor amount of propylene, a similar carbon 
monoxide/ethylene/propylene terepolymer will be obtained.