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

• Published in: Journal of polymer science. Part A, Polymer chemistry Polymer chemistry, 2009-12, Vol.47 (23), p.6715-6725
• Main Authors: Sunjuk, Mahmoud, Al-Noaimi, Mousa, Al-Degs, Yahya, Al-Qirem, Tareq, Lindner, Ekkehard, Abu-Surrah, Adnan S
• Format: Article
• Language: English
• Subjects: Applied sciences; catalyst; Copolymerization; Exact sciences and technology; Organic polymers; palladium; Physicochemistry of polymers; polyketones; Preparation, kinetics, thermodynamics, mechanism and catalysts; water-soluble; α-olefins
• ISSN: 0887-624X; 1099-0518
• DOI: 10.1002/pola.23713

Water-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 x 10⁴ g mol⁻¹), and narrow polydispersities (Mw/Mn [almost equal to] 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.