Copolymerization of styrene with CO catalysed by palladium-substituted 1,10-phenanthroline bis(methoxycarbonyl) complexes [Pd(L—L)(COOMe)2]
✍ Scribed by Roberto Santi; Anna Maria Romano; Rossella Garrone; Luigi Abbondanza; Mario Scalabrini; Giancarlo Bacchilega
- Publisher
- John Wiley and Sons
- Year
- 1999
- Tongue
- English
- Weight
- 67 KB
- Volume
- 200
- Category
- Article
- ISSN
- 1022-1352
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✦ Synopsis
A new class of highly effective homogeneous palladium bis(methoxycarbonyl) complexes Pd(L1L)(COOMe) 2 , where (L1L) are substituted phenanthroline ligands, has been developed for the production of syndiotactic alternating styrene-carbon monoxide copolymers. The essential feature of this novel catalytic system is that it is formed by palladium complex, Pd(L1L)(COOMe) 2 , an acid cocatalyst, (L1L)HPF 6 , bearing a weakly coordinating counter anion, and an oxidant, such as 1,4-naphthoquinone (1,4-NQ). The palladium/acid cocatalyst molar ratio has been explored. A maximum of copolymerization activity was obtained at 1/1 molar ratio. For a series of palladium catalysts, Pd(phen)(COOMe) 2 appeared to be the most active one. The effect of substituents at the ligand in Pd(L1L)(COOMe) 2 on the copolymerization activity was studied. The tacticity of alternating copolymers obtained with different Pd(L1L)(COOMe) 2 catalysts was determined by NMR spectroscopy. The copolymers were thermally characterised by TGA and DSC.