Higher α‐olefins carbonylation in aqueous media by Pd(II) catalysts modified with substituted diphosphine ligands: Aqueous polyketone latices with high solid contents and molecular weights

Abstract

AbstractWater‐soluble palladium complexes cis‐[Pd(L)(OAc)2] (1–8) (L represents a diphosphine ligands of the general formula CH2(CH2PR2)2, where for a: R  (CH2)6OH; b–g: R  (CH2)nP(O)(OEt)2, n = 2–6 and n = 8; h: R  (CH2)3NH2) have been employed, after activation with a large excess of HBF4, for emulsion polymerization of alkenes (propene, butene, and their equimolar mixtures) with carbon monoxide. Aliphatic polyketone lattices with a high solid content (21%), high molecular weight (6.3 × 104 g mol−1), and narrow polydispersities (Mw/Mn ≈ 2) were isolated. The catalytic activity of the dicationic palladium (II) based catalysts, C1–C8 is highly dependent on the length of the alkyl chain of the ligand. Catalyst 3 proved to be highly active for propene/CO copolymers, whereas 6 is active for butene/CO and propene/CO‐butene/CO systems. The presence of methyl β‐cyclodextrin, as a phase‐transfer agent, and undecenoic acid, as an emulsifier, increase the molar mass and the stability of the polyketones and finally the activity of the catalyst. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 6715–6725, 2009