Process for the polymerization of cycloolefins

Cycloolefins of 8 or 12 carbon atoms and with one or more non-conjugated double bonds in the ring can be polymerized, optionally in the presence of a solvent, with the aid of a catalyst of tungsten hexachloride and cis,trans-1,5-cyclodecadiene as the cocatalyst.

BACKGROUND OF THE INVENTION 
The present invention relates to a process for the polymerization of 
cycloolefins of 8 or 12 carbon atoms having one or more isolated, i.e., 
non-conjugated, double bonds in the ring, optionally in the presence of a 
solvent, with the aid of a catalyst consisting of tungsten hexachloride 
and a cocatalyst. 
The production of polyalkenamers from cycloolefins with the aid of 
metathesis catalysts is conventional, e.g. see G. Dall'Asta in "Makromol. 
Chem." (Macromolecular Chemistry) 154 : 1-19 (1972). Metathesis catalysts 
are homogeneous and heterogeneous catalysts containing compounds of metals 
of subgroups V-VII of the periodic table, primarily those of niobium, 
tantalum, molybdenum, tungsten and rhenium, as well as optionally 
compounds of the metals of main groups I-III of the periodic table, e.g., 
the alkyls or hydrides thereof, if desired with additional ligands, e.g., 
halogen, alkoxy or carboxylate or, in place thereof, Lewis acids. The 
metathesis catalysts can also include, as is known, further activating 
additives, such as alcohols, epoxides, tert.-butyl hypochlorite, 
peroxides, carboxylic acids, aromatic nitro compounds, vinyl halides, 
vinyl and allyl ethers and esters, etc.; see for example, DAS (German 
Published Application) No. 1,072,811; French Pat. Nos. 1,394,380 and 
1,467,720; Dutch Pat. Applications Nos. 65-10331, 66-05105, 66-14413, 
67-04424, 67-14559, 68-06208, 68-06211 and 68-06209. 
Since the customary alkyl or hydride compounds of main groups I-III of the 
periodic table are both expensive and generally difficult to handle, 
attempts have been made to conduct metathesis reactions without adding 
such compounds. 
For example, it is known from Italian Pat. 784,307 that a small amount of 
polymer is obtained after long reaction times by treating cyclopentene 
with tungsten hexachloride. 
Furthermore, a process for the polymerization of various cycloolefins is 
known from DOS (German Unexamined Laid-Open Application) No. 1,909,226 
wherein, inter alia, tungsten hexachloride and an aluminum trihalide are 
utilized as the catalyst system. 
It is furthermore known that 1,5-cyclooctadiene can be converted into 
polymers with a combination of tungsten hexachloride and phenyl 
diazomethane, as reported in "Eur. Polym. J.", 10 : 901 (1974). 
Finally, it is known from DOS No. 2,332,564 to polymerize 
1,5-cyclooctadiene with halides of tungsten, molybdenum, tantalum or 
rhenium as the catalyst in the presence of certain 
bicyclo-[2,2,1]-1,5-heptadienes. 
All of these processes of the prior art have at least one of the following 
disadvantages: 
1. A low activity of the catalyst system employed and consequently a high 
amount of catalyst required, leading to high ash contents in the polymers. 
2. Poor solubility of the catalyst components and ensuing difficulties in 
dosing of the catalyst. 
3. Low selectivity of polyalkenamer formation by the favoring of undesired 
secondary reactions. 
4. Use of expensive or difficult-to-produce compounds as the cocatalysts. 
It is, therefore, an object of this invention to mitigate or overcome the 
above disadvantages of the processes of the relevant prior art. 
Upon further study of the specification and appended claims, further 
objects and advantages of this invention will become apparent to those 
skilled in the art. 
SUMMARY OF THE INVENTION 
Briefly, the above and other objects, features and advantages of the 
present invention are attained in one aspect thereof by providing a 
process for the polymerization of a cyloolefin monomer of 8 or 12 carbon 
atoms having one or more non-conjugated double bonds in the ring with the 
aid of a catalyst consisting of tungsten hexachloride and a cocatalyst, 
the improvement which comprises employing cis,trans-1,5-cyclodecadiene as 
the cocatalyst in a molar ratio to tungsten hexachloride of at least 2 : 
1. 
DETAILED DISCUSSION 
It has now been found that cycloolefins of 8 or 12 carbon atoms and with 
one or more non-conjugated double bonds in the ring can be polymerized, 
optionally in the presence of a solvent, with the aid of a catalyst of 
tungsten hexachloride and cis,trans-1,5-cyclodecadiene as the cocataylst. 
This is surprising insofar as it is known from the literature, e.g., J. 
Polym. Sci. [B] 11 : 263 (1973), that cis,trans-1,5-cyclodecadiene cannot 
be polymerized at a temperature of 30.degree. C. under the effect of 
tungsten hexachloride. 
Cycloolefins of 8 or 12 carbon atoms and with one or more non-conjugated 
double bonds in the ring are preferably the hydrocarbons cis-cyclooctene, 
cis,cis-1,5-cyclooctadiene, cyclododecene (pure or as a mixture of 
isomers) and cic,trans,trans-1,5,9-cyclododecatriene. The cycloolefins can 
be polymerized individually to form homopolymers or with one another to 
form random, block or graft copolymers. cis,cis-1,5-Cyclooctadiene and 
cis,trans,trans-1,5,9-cyclododecatriene are obtainable by the catalytic 
cyclodimerization and/or cyclotrimerization of butadiene described in 
"Liebigs Ann. Chem." (Liebigs Annals of Chemistry) 727 : 143 (1969). From 
these compounds, cis-cyclooctene and the isomer mixture of cyclododecene 
can be prepared by partial hydrogenation, e.g. in accordance with the 
process of German Pat. No. 1,277,852. 
The process of this invention can be accomplished with or without inert 
solvents or diluents which do not deleteriously affect the course of the 
reaction, e.g., aliphatic alicyclic, aromatic and halogenated hydrocarbons 
which include but are not limited to pentane, hexane, heptane, n- and 
isooctane, isononane (hydrogenated trimer propene), n-decane, isododecane 
(hydrogenated tetramer propene); cyclopentane, cyclohexane, 
methylcyclopentane, methylcyclohexane, ethylcyclohexane, 
isopropylcyclohexane, cyclooctane, decahydronaphthalene; hydrogenated 
terpenes, such as pinane and camphane; cyclohexene and it substitution 
products; benzene, toluene, o-, m-, p-xylene, ethylbenzene, o-, m-, 
p-diethylbenzene, n-propylbenzene, isopropylbenzene and other mono- to 
polyalkylbenzenes; tetrahydronaphthalene; methylene chloride, chloroform, 
carbon tetrachloride, 1,2-dichloroethylene, trichloroethylene, 
tetrachloroethylene, chlorobenzene, o-dichlorobenzene, trichlorobenzene 
(mixture of isomers), bromobenzene, fluorobenzene and 1,2-dichloroethane, 
either singly or in admixtures of two or more. 
It is essential that the solvents, as well as the reactants, be employed 
substantially free of water and other H-acidic compounds, as well as 
compounds having an electron donor function (Lewis bases) and peroxides. 
Except for very small quantities which may be added to attain specific 
effects, such impurities generally impair the activity of the catalyst. 
The cis,trans-1,5-cyclodecadiene utilized as the cocatalyst together with 
the commercially available tungsten hexachloride is obtainable in a simple 
manner by co-ligomerization of 2 moles of 1,3-butadiene with one mole of 
ethylene in accordance with methods known in the art, e.g., "Angew. Chem." 
(Applied Chemistry) 75 : 10 (1963) and "Liebigs Ann. Chem." 727 : 183 
(1969). 
Just as with the reactants and the solvents when used, the cocatalyst must 
likewise be free of water and other H-acidic compounds, as well as of 
compounds having donor functions and peroxides. This can be attained by 
methods known in the art, e.g., by percolating the 
cis,trans-1,5-cyclodecadiene, immediately prior to use, over aluminum 
oxide under dry inert gas. 
The molar ratio of the monomeric cycloolefins of 8 or 12 carbon atoms to 
the tungsten hexachloride catalyst in the present process is generally 
between 50 and 10,000, preferably between 500 and 2,500, and especially 
between 1,000 and 2,000. The lower limit of the molar ratio is determined 
by the known Friedel-Crafts activity of tungsten hexachloride, which can 
lead to undesirable by-products, while the upper limit is fixed by the 
possible inactivation of the catalyst system by impurities. 
The molar ratio of cis,trans-1,5-cyclodecadiene to tungsten hexachloride 
must be at least 2 : 1 in the process of this invention. Specifically, 
this ratio is preferably during the polymerization of cis-cyclooctene, 
20-60 : 1, during the polymerization of cis,cis-1,5-cyclooctadiene, 5-30 : 
1; during the polymerization of cyclododecene, 20-250 : 1; and during the 
polymerization of cis,trans,trans-1,5,9-cyclododecatriene, 10-70 : 1. 
The process of this invention can be conducted discontinuously as well as 
continuously at temperatures of -20.degree. to +80.degree. C., preferably 
+10.degree. to +40.degree. C. under pressures sufficient to maintain the 
reaction mixture in the liquid phase. In general, the polymerization is 
effected by providing the cycloolefin or cycloolefins to be polymerized, 
optionally together with a solvent or solvent mixture, and subsequently 
first adding a solution of tungsten hexachloride in a suitable solvent, 
e.g. benzene, and thereafter the cocatalyst, if desired together with a 
diluent. The sequence of adding the catalyst components is not critical, 
but it is recommended in cases of low monomer : tungsten hexachloride 
ratios to first add the cocatalyst. The molecular weight of the 
polyalkenamers producible in accordance with this invention can be 
optionally controlled by adding suitable compounds, e.g. acyclic alkenes 
with one or more non-conjugated double bonds, which can be terminal- or 
interiorly positioned and which should not carry any substituents. Such 
compounds include but are not limited to 1-pentene, 1-hexene, 1-heptene, 
1-octene, 2-pentene and 7 -tetradecene. The addition of the controlling 
compound should be effected if at all possible prior to the addition of 
the second catalyst component, but at the latest sufficiently well before 
the inactivation of the catalyst so athat the intended regulation of the 
molecular weight still occurs. 
The polymrization is terminated after the desired reaction time by 
inactivating the catayst, e.g., by adding an H-acidic compound. 
Thereafter, the polyalkenamers are isolated and purified in a conventional 
manner. If the polyalkenamers are obtained in a solution or in the liquid 
phase, the catalyst residues are removed after stopping the 
polymerization, e.g. by washing out the polymer-containing phase with an 
aqueous or aqueous-alcoholic solution of agents having a dissolving effect 
on the catalyst residues which initially are present as compounds of the 
H-acidic materials. Such compounds having a dissolving effect are, for 
example, acids, bases or complexing agents, e.g. acetylacetone, citric or 
tartaric acid, ethylenediaminetetraacetic acid, nitrilotriacetic acid, 
etc. Thereafter, the polymers are separated by precipitation (e.g. pouring 
into a precipitant, such as methanol, isopropanol or acetone) or by 
removing the solvent by distillation (e.g. by blowing steam into the 
polymer solution or by introducing the latter through nozzles into hot 
water). If the polymers are precipitated from the solution of the monomer 
in the form of flakes or in powdery form, they can also be separated from 
the liquid by filtraton, centrifugation or decantation and then they can 
be subjected to the treatment for the removal of the catalyst residues. To 
protect against oxidaton, gelling and other aging phenomena, it is 
possible to admix stabilizers with the polyalkenamers in various stages of 
the working-up operation, e.g. aromatic amines or sterically hindered 
phenols. Likewise, further purification can be conducted by a 
reprecipitation of the polymer, if this should prove necessary. After 
these steps, the polymer is dried in a conventional manner. 
The polyalkenamers which can be produced according to the process of this 
invention are suitable, for example, in the low-molecular weight range, 
optionally after additional reactions, as binders for coating compounds 
and, in the high-molecular weight range, predominantly as a raw material 
for the production of elastomeric or thermoplastic molded components. The 
specific purpose for which they are used depends on the type of the 
monomer, the molecular weight, and the proportion of cis- and trans-double 
bonds in the polyalkenamers, as is known in the art. 
The following examples serve for an additional explanation of the 
invention. The reduced specific viscosity (RSV) was measured in all cases 
at 135.degree. C. in decahydronaphthalene. To determine the 
cis-trans-C.dbd.C ratio, the absorption band at 730 cm.sup.-1 in the 
infrared spectra of the polymers was evaluated.