Carbon monoxide, copolymerization with

In addition to a-olefins, p-/-butylstyrene can be used as a comonomer for the isotactic specific copolymerization with carbon monoxide with chiral induction [32], Whereas bipyridyl as ligand gives a syndiotactic polymer, the Pd-catalyzed polymerization with ligand 11 leads to a polymer with isotacticity of over 98% and high optical activity ([ ]D -536° (in CH2C12)) [33, 34]. The BINAPHOS catalyst described above is also effective in this type of copolymerization [25],... 

When l-olefins are used as the substrate for the copolymerization with carbon monoxide, different moieties can form due to the absence of symmetry elements relating to the two unsaturated carbon atoms and to the enantiofaces of the olefin substrate (four different insertion pathways) (Scheme 8.11) [29]. 

Similar photodegradation may also be achieved by incorporating ketone groups into polymers by copolymerization with carbon monoxide [Hartley and Guillet, 1968]. These polymers could be made more sensitive to UV by mixing them with metallic oxides or salts, viz. Fe Oj. Relative rates of UV degradation of ethylene-co-carbon monoxide (1% CO), LDPE + transition metal sensitizer, and LDPE -I- 6 wt% starch -I- transition metal sensitizer are illustrated in Figure 16.12. 

Homolytic bond cleavage, producing free radicals used in block copolymer formation, has also been reported. One of the first examples was the mastication of natural rubber swollen with methyl methacrylate (9). Photolytic degradation of polystyrene, capped with bromine containing groups (10) or copolymerized with carbon monoxide (11), has also been used in block copolymer preparation. Similarly ultrasonic degradation of homopolymers in the presence of a second monomer has been reported (12). 

Ethylene and other olefins can also be copolymerized with carbon monoxide to form polymers of aliphatic ketones, using transition metal catalysts, like paUadium(ll) coupled with non-coordinating anions. There are numerous reports of such catalysts in the literature. One example is a compound composed of bidentate diarylphosphinopropane ligand and two acetonitrile molecules coordinating Pd coupled with BF3 counterions. This compound, bis(acetonitrile)palladium(II)-l,3-bis(diphenyl-phosphino)propane-(tetrafluoborate), can be illustrated as follows [97] ... 

The deliberate introduction of carbonyl groups into polymers, either in the main chain by copolymerization with carbon monoxide or in the side chains by copolymerization with vinyl ketones, is the basis of at least one type of plastic designed to photodegrade rapidly in outdoor exposure (115). These copolymers are widely used in the United States for the six-pack ring packaging of soft drinks, whose damaging effect on marine life has been of great concern. 

Nozaki, K. Komaki, H. Kawashima, Y. Hiyama, T. Matsubara, T. Predominant 1,2-insertion of styrene in the Pd-catalyzed alternating copolymerization with carbon monoxide. J. Am. Chem. Soc. 2001,123, 534-544. 

An alternative method of introducing ketone groups into polymers, useful so far only in low-density polyethylene made by the high-pressure process, is copolymerization with carbon monoxide. Although such copolymers have been known for many years, their UV photochemistry (and hence usefulness in this application) was first reported by Hartley and Guillet [9] in 1968. These copolymers are manufactured on a large scale in the US by several major plastics producers. 

Figure 10 Functionalized olefins copolymerized with carbon monoxide by Pd complex bearing Me-DUPHOS or BINAPHOS.

Copolymers of carbon monoxide, carbon dioxide, sulfur dioxide or carbon disulfide are frequently formed in combination with oxiranes, thiiranes or aziridines. Copolymerization of carbon monoxide and ethylenimine was carried out under radiation and the formation of 3-nylon was observed238. ... 

The insertion of unsaturated molecules into metal-carbon bonds is a critically important step in many transition-metal catalyzed organic transformations. The difference in insertion propensity of carbon-carbon and carbon-nitrogen multiple bonds can be attributed to the coordination characteristics of the respective molecules. The difficulty in achieving a to it isomerization may be the reason for the paucity of imine insertions. The synthesis of amides by the insertion of imines into palladium(II)-acyl bonds is the first direct observation of the insertion of imines into bonds between transition metals and carbon (see Scheme 7). The alternating copolymerization of imines with carbon monoxide (in which the insertion of the imine into palladium-acyl bonds would be the key step in the chain growth sequence), if successful, should constitute a new procedure for the synthesis of polypeptides (see Scheme 7).348... 

Palladium(II) complexes possessing bidentate ligands are known to efficiently catalyze the copolymerization of olefins with carbon monoxide to form polyketones.594-596 Sulfur dioxide is an attractive monomer for catalytic copolymerizations with olefins since S02, like CO, is known to undergo facile insertion reactions into a variety of transition metal-alkyl bonds. Indeed, Drent has patented alternating copolymerization of ethylene with S02 using various palladium(II) complexes.597 In 1998, Sen and coworkers also reported that [(dppp)PdMe(NCMe)]BF4 was an effective catalyst for the copolymerization of S02 with ethylene, propylene, and cyclopentene.598 There is a report of the insertion reactions of S02 into PdII-methyl bonds and the attempted spectroscopic detection of the copolymerization of ethylene and S02.599... 

Copolymerization of Epoxides and Aziridines with Carbon Monoxide... 

Drent, E. van Broekhoven, J. A. M. Doyle, M. J. Wong, P. K. Palladium Catalyzed Copolymerization of Carbon Monoxide with Alkenes to Alternating Polyketones and Polyspiroketals. Fink, G. Muelhaupt, R. Brintzinger, H. H. Eds. Ziegler Catal. Springer, Berlin, 1995, pp 481 496. 

There is a tendency toward alternation in the copolymerization of ethylene with carbon monoxide. Copolymerizations of carbon monoxide with tetrafluoroethylene, vinyl acetate, vinyl chloride, and acrylonitrile have been reported but with few details [Starkweather, 1987]. The reactions of alkenes with oxygen and quinones are not well defined in terms of the stoichiometry of the products. These reactions are better classified as retardation or inhibition reactions because of the very slow copolymerization rates (Sec. 3-7a). Other copolymerizations include the reaction of alkene monomers with sulfur and nitroso compounds [Green et al., 1967 Miyata and Sawada, 1988]. 

Bis(oxazoline) ligands have also been used to produce polymers containing main chain chirality. Some examples include those by Wagner and co-workers in which /-pr-box 45 is used to mediate the copolymerization of tert-butylstyrene 192 with carbon monoxide to achieve a polymer of type 193 with stereoregularity up to 98%, ° ° Oishi and co-workers polymerization of A-substimted maleimides... 

Alternating copolymerization of carbon monoxide with ethene was discovered in the early 1950s [112] and has been attracting much interest lately. Among the several metals such as, Ni(II), Pd(II), and Rh(I) that can promote this reaction [113], Pd(II) complexes with a cis-chelating diphosphine ligand and a non-coordinating counter anion were selected as the catalysts of choice and have been studied extensively [114,115]. 

The first successful example of asymmetric copolymerization of propene with carbon monoxide was reported in 1992 and used a Pd complex with a chiral electron-rich bisphosphine... 

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