An interfacial polymerisation approach is adopted to encapsulate palladium(II) acetate and palladium nanoparticles in polyurea microcapsules for use in catalysis.

No abstract

Benzene is oxidized by oxygen utilizing the dioxygenase enzyme contained in the microorganism Pseudomonas putida. Genetic manipulation produced a variant that gave exclusively the initial oxidation product of benzene the cis-dihydrocatechol(2) in practical quantities. Derivatives of the latter, in particular the methyl carbonate, can be obtained pure and are very stable. They polymerize in the absence of solvent with radical initiators to give a polymer (4). The latter is soluble in solvents such as acetone and methylene chloride and readily forms coherent coatings and films. On heating methanol and C 0 2 are expelled and polyphenylene is formed as a coating or film. The aromatization process is catalyzed by bases and can occur well below the glass-transition temperature of the precursor polymer of 185 "C. The aromatization can occur under homogeneous conditions in the basic solvent N-methylpyrrolidone. Surprisingly, these partially aromatized molecules are soluble even at conversion to 30% phenyl groups. The latter studies can be used to measure the glass transition of polyphenylene that was found to be 283 "C. Neutron scattering studies have shown that the precursor polymer is a random coil. Viscosity measurements show that there is a coil-rod transition on aromatization in N-methylpyrrolidone. Crystallographic data on polyphenylene crystallized above its glass transition and the thermal and electrical properties are described.

Starting from benzene and oxygen and using the genetically modified bacteria Pseudominium putida as an oxidation catalyst compound (6) is readily obtained; derivatives of the latter are soluble in organic solvents and polymerise to give a soluble precursor (5) which can be used to make fibres and films which on heating are converted into polyphenylene fibres and films.

[reaction: see text] Osmium tetroxide has been microencapsulated in a polyurea matrix using an in situ interfacial polymerization approach. These microcapsules have been effectively used as recoverable and reusable catalysts in the dihydroxylation of olefins