Functional group tolerance and accessibility of unique microstructures are attractive features of olefin polymerization by late transition metal catalysts. Recent discovery of several new classes of highly active catalysts provide access to a range of new materials.

Various phosphinesulfonato ligands and the corresponding palladium complexes [{((P^O)PdMeCl)-μ-M}(n)] ([{((X)1-Cl)-μ-M}(n)], (P^O) = κ(2)-P,O-Ar(2)PC(6)H(4)SO(2)O) with symmetric (Ar = 2-MeOC(6)H(4), 2-CF(3)C(6)H(4), 2,6-(MeO)(2)C(6)H(3), 2,6-(iPrO)(2)C(6)H(3), 2-(2',6'-(MeO)(2)C(6)H(3))C(6)H(4)) and asymmetric substituted phosphorus atoms (Ar(1) = 2,6-(MeO)(2)C(6)H(3), Ar(2) = 2'-(2,6-(MeO)(2)C(6)H(3))C(6)H(4); Ar(1) = 2,6-(MeO)(2)C(6)H(3), Ar(2) = 2-cHexOC(6)H(4)) were synthesized. Analyses of molecular motions and dynamics by variable temperature NMR studies and line shape analysis were performed for the free ligands and the complexes. The highest barriers of ΔG(‡) = 44-64 kJ/mol were assigned to an aryl rotation process, and the flexibility of the ligand framework was found to be a key obstacle to a more effective stereocontrol. An increase of steric bulk at the aryl substituents raises the motional barriers but diminishes insertion rates and regioselectivity. The stereoselectivity of the first and the second methyl acrylate (MA) insertion into the Pd-Me bond of in situ generated complexes (X)1 was investigated by NMR and DFT methods. The substitution pattern of the ligand clearly affects the first MA insertion, resulting in a stereoselectivity of up to 6:1 for complexes with an asymmetric substituted phosphorus. In the consecutive insertion, the stereoselectivity is diminished in all cases. DFT analysis of the corresponding insertion transition states revealed that a selectivity for the first insertion with asymmetric (P^O) complexes is diminished in the consecutive insertions due to uncooperatively working enantiomorphic and chain end stereocontrol. From these observations, further concepts are developed.

We report a novel polyester material generated from readily available biobased 1,18‐octadecanedicarboxylic acid and ethylene glycol possesses a polyethylene‐like solid‐state structure and also tensile properties similar to high density polyethylene (HDPE). Despite its crystallinity, high melting point (Tm=96 °C) and hydrophobic nature, polyester‐2,18 is subject to rapid and complete hydrolytic degradation in in vitro assays with isolated naturally occurring enzymes. Under industrial composting conditions (ISO standard 14855‐1) the material is biodegraded with mineralization above 95 % within two months. Reference studies with polyester‐18,18 (Tm=99 °C) reveal a strong impact of the nature of the diol repeating unit on degradation rates, possibly related to the density of ester groups in the amorphous phase. Depolymerization by methanolysis indicates suitability for closed‐loop recycling.

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Dicarboxylic acids are compounds of high value,\ud but to date long-chain α,ω-dicarboxylic acids have been\ud difficult to access in a direct way. Unsaturated fatty acids are\ud ideal starting materials with their molecular structure of long\ud methylene sequences and a carboxylate functionality, in\ud addition to a double bond that offers itself for functionaliza-\ud tion. Within this paper, we established a direct access to α,ω-\ud dicarboxylic acids by combining isomerization and selective\ud terminal carbonylation of the internal double bond with water\ud as a nucleophile on unsaturated fatty acids. We identified the\ud key elements of this reaction: a homogeneous reaction mixture\ud ensuring sufficient contact between all reactants and a catalyst\ud system allowing for activation of the Pd precursor under\ud aqueous conditions. Experiments under pressure reactor\ud conditions with [(dtbpx)Pd(OTf)2] as catalyst precursor revealed the importance of nucleophile and reactant concentrations and the addition of the diprotonated diphosphine ligand (dtbpxH2)(OTf)2 to achieve turnover numbers >120. A variety of unsaturated fatty acids, including a triglyceride, were converted to valuable long-chain dicarboxylic acids with high turnover numbers and selectivities for the linear product of >90%. We unraveled the activation pathway of the PdII precursor, which proceeds via a reductive elimination step forming a Pd0 species and oxidative addition of the diprotonated diphosphine ligand, resulting in the formation of the catalytically active Pd hydride species. Theoretical calculations identified the hydrolysis as the rate-determining step. A low nucleophile concentration in the reaction mixture in combination with this high energetic barrier limits the potential of this reaction. In conclusion, water can be utilized as a nucleophile in isomerizing functionalization reactions and gives access to long-chain dicarboxylic acids from a variety of unsaturated substrates. The activity of the catalytic system of hydroxycarbonylation ranks as one of the highest achieved for isomerizing functionalizations in combination with a high selectivity for the linear product