Synthesis and properties of polymers with unusual structure

Abstract

This lecture summarize some recent results of our current research. The first part describes the homopolymerization and copolymerization o f a monocyclic and two bicyclic unsaturated acetals. In this way polyacetals with 1,4-cis-butadiene units and cyclohexene units respectively are obtained. Secondly, the N-substitution of polyamides is described. By N-metalation and subsequent alkylation comb-like polyamides are available. Longer branches cause a side-chain crystallinity. The anionicl'grafting-from"technique forms irregular branched polyamides. By termination reaction between living ends of poly( 2 -i s o p r o p e n y l n a p h t h a l e n e ) and suitable electrophiles new macromonomers are available. The last part describes their copolymerization with butyl methacrylate.Polymers with unusual structure can be obtained by polymerizing new, unusual monomers or by chemical modification of known polymers. In the following paper, examples for both of the methods mentioned above will be described. 0252-1997f85lUS $0.200

Carbon monoxide hydrogenation using manganese oxide-based catalysts: effect of operating conditions on alkene selectivity

“…As the temperature is increased for this system, secondary alkene hydrogenation becomes significant (e.g., at 220 °C, the mole fraction C2 alkene/mole fraction C3 alkene is in the range 0.2-0.4). This observation is consistent with the effect of increasing temperature for other carbon monoxide hydrogenation catalysts (Schulz, 1985).…”

“…It is known that both alkanes and alkenes can be primary products from carbon monoxide hydrogenation (Schulz, 1985), and of these the preferred products for the lower hydrocarbons are the alkenes. The effect of the operating conditions on the alkene/alkane rdtio was therefore investigated, and plots of this ratio against space time at constant temperature are shown in Figures 4 and 5 for Fe/MnO and Co/MnO, respectively.…”

“…Open symbols, Fe/MnO catalyst, 300 °C; closed symbols, Co/MnO catalyst, 190 °C: ( ) average mol % alkene in C3 fraction (primary alkene selectivity); (A) mol % C2H4 in C2 fraction/mol % C3H6 in C3 fraction (secondary hydrogenation). Schulz (1985) has noted for these matrix catalysts that primary alkene selectivity can be quantified in terms of the average mol % alkene in the C3/C4 fraction. Similarly the secondary alkene hydrogenation can be characterized by the mol % alkene in the C2 fraction compared to the mol % alkene in the C3 fraction, which when close to 1.0 indicates that the system is mainly one of primary alkene selectivity.…”

“…For a number of years it has been known that Fe/ oxide catalysts can give high alkene selectivity with low methane selectivity (Kolbel and Tillmetz, 1976; Bussemeier et al, 1976). These catalysts are known to contain iron/manganese oxide solid solutions (Hutchings and Boeyens, 1986) and have been termed matrix catalysts (Schulz, 1985). Cornils et al (1984) have shown that the yield of C2-C4 alkenes with this type of catalyst is highly dependent on the reaction conditions.…”