ISSN:
0360-6376
Schlagwort(e):
Physics
;
Polymer and Materials Science
Quelle:
Wiley InterScience Backfile Collection 1832-2000
Thema:
Chemie und Pharmazie
Notizen:
Soluble tricarbonylchromium complexes were made by reacting Cr(CO)6 with a ladder polyphenylsilsesquioxane and a linear polydiphenylsiloxane. These new polymer Cr(CO)3 complexes were characterized by elemental Cr, infrared (IR), gel permeation chromatography (GPC), viscosity, and thermal analyses and were evaluated as stereoselective hydrogenation catalysts. Thermogravimetry studies demonstrated that the new complexes were more stable at 180-200°C in N2 than the corresponding complex from crosslinked polystyrene. These silicone polymer complexes catalyzed stereoselective hydrogenation of methyl sorbate to cis-3-hexenoate in cyclohexane and tetrahydrofuran (THF) and could be recovered from THF for recycling by precipitation-fiItration. Catalytic activity and recyclability, however, were highly influenced by the solvent. Loss of catalytic activity associated with loss of Cr(CO)3 was observed on recycling. These results support a mechanisim that involves dissociation of Cr(CO)3, a significant portion of which cannot become reassociated with the polymer phenyl groups.
Zusätzliches Material:
4 Ill.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1002/pol.1980.170180824
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