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Single-Step Access to Long-Chain α,ω-Dicarboxylic Acids by Isomerizing Hydroxycarbonylation of Unsaturated Fatty Acids

Single-Step Access to Long-Chain α,ω-Dicarboxylic Acids by Isomerizing Hydroxycarbonylation of Unsaturated Fatty Acids

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GOLDBACH, Verena, Laura FALIVENE, Lucia CAPORASO, Luigi CAVALLO, Stefan MECKING, 2016. Single-Step Access to Long-Chain α,ω-Dicarboxylic Acids by Isomerizing Hydroxycarbonylation of Unsaturated Fatty Acids. In: ACS Catalysis. 6(12), pp. 8229-8238. eISSN 2155-5435

@article{Goldbach2016-12-02Singl-39190, title={Single-Step Access to Long-Chain α,ω-Dicarboxylic Acids by Isomerizing Hydroxycarbonylation of Unsaturated Fatty Acids}, year={2016}, doi={10.1021/acscatal.6b02622}, number={12}, volume={6}, journal={ACS Catalysis}, pages={8229--8238}, author={Goldbach, Verena and Falivene, Laura and Caporaso, Lucia and Cavallo, Luigi and Mecking, Stefan} }

Goldbach, Verena eng Cavallo, Luigi 2016-12-02 Cavallo, Luigi Goldbach, Verena 2017-06-09T09:26:16Z Mecking, Stefan Dicarboxylic acids are compounds of high value, but to date long-chain α,ω-dicarboxylic acids have been difficult to access in a direct way. Unsaturated fatty acids are ideal starting materials with their molecular structure of long methylene sequences and a carboxylate functionality, in addition to a double bond that offers itself for functionalization. Within this paper, we established a direct access to α,ω-dicarboxylic acids by combining isomerization and selective terminal carbonylation of the internal double bond with water as a nucleophile on unsaturated fatty acids. We identified the key elements of this reaction: a homogeneous reaction mixture ensuring sufficient contact between all reactants and a catalyst system allowing for activation of the Pd precursor under aqueous conditions. Experiments under pressure reactor 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. Mecking, Stefan Caporaso, Lucia 2017-06-09T09:26:16Z Caporaso, Lucia Falivene, Laura Single-Step Access to Long-Chain α,ω-Dicarboxylic Acids by Isomerizing Hydroxycarbonylation of Unsaturated Fatty Acids Falivene, Laura

Dateiabrufe seit 09.06.2017 (Informationen über die Zugriffsstatistik)

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