Acetylene, polymerization with epoxide

ROMP and PROMP are very useful methods to synthesize a number of novel materials with unique properties. Poly(cyclooctenes), poly(norbornenes) and poly(acetylenes) were discussed in more details and some of their properties like Tg, cristallinity, oxygen permeability, dielectric properties etc. listed. The polymerization of the cycloolefins was done either thermally or photochemically with the "old" Ru(II)-salts and the later developed Ru-phosphines as catalysts, whereas substituted acetylenes were photo-polymerized with W-, Mo- and Ta-catalysts. In addition, polymeranalogous transformations of the double bonds in ROMP polymers, (additions and cyclo-additions, epoxidation, (photo) crosslinking etc.) were discussed. We are convinced that these materials and systems will find useful applications in the near future. 

Week et al. [65] further reported the Co salen complex supported on norbomene polymers (23, 24) with stable phenylene-acetylene linker (Figure 8). The polymer-supported salen catalysts were investigated for HKR of the racemic terminal epoxides that showed outstanding catalytic activities and comparable selectivities to the original catalysts reported by Jacobsen. However, the polymeric catalyst was recycled only once after its precipitation with diethylether as the catalyst became less soluble and less reactive in subsequent catalytic... 

This unified volume explains the mechanistic basics of tactic polymerizations, beginning with an extensive survey of the most important classes of metallocene and post-metallocene catalysts used to make polypropylenes. It also focuses on tactic stereoblock and ethylene/propylene copolymers and catalyst active site models, followed by chapters discussing the structure of more stereochemically complex polymers and polymerizations that proceed via non-vinyl-addition mechanisms. Individual chapters thoroughly describe tactic polymerizations of a-olefins, styrene, dienes, acetylenes, lactides, epoxides, acrylates, and cyclic monomers, as well as cyclopolymerizations and ditactic structures, olefin/CO copolymers, and metathesis polyalkenamers. 

Under air-free conditions, Ti(OBu)4 (0.2 M solution) in toluene was mixed with the ketone-modified carrier polymer and a known amount of acetylene dissolved in toluene, lb form the active catalyst, AlEt3 (4 equiv relative to Ti) in toluene was injected into the mixture. The homogenous reaction mixture was then stirred at room temperature. The PA chains formed with nucleophilic ends (connected to the Ti center), and the polymerization reaction terminated when these chain ends encountered one of the electrophilic ketone sites on the carrier polymer to form the grafted side-chain. The whole reaction was done within minutes. The catalyst was then quenched with dilute acid, which also prevented cross-linking at any unreacted epoxides. By adjusting the ratio between acetylene pressure and the number of graft sites, the... 

Explain the following observations (a) Ru(CO) Ij and Pt(CO)jIj act as promoters in Ir-catalyzed carbonylation but not in Rh-catalyzed carbonylation of methanol (b) in the concentration of LP ([LP]) versus initial rate plots of methyl acetate carbonylation, at low [Li ] the initial rate increases and then at higher [LP] it levels off (c) acetaldehyde and propionic acid are side products of Rh- and Ir-catalyzed carbonylations (d) instead of methyl acetate, dimethylether can also be carbonylated to give acetic anhydride (e) in the Pd-catalyzed carbonylation of methyl acetylene, the amount of CHjCH=CH(C02Me) formed is very httle (f) Co-catalyzed carbonylation of benzyl chloride to phenyl acetic acid requires a phase-transfer catalyst (g) a neutral catalytic intermediate may be involved in Rh-catalyzed WGS reaction (h) complexes of the general formula A X where A is a Lewis acid are effective catalysts for polymerizing epoxides with CO (i) reaction... 

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