Studies aimed at synthesizing surfactants from biomass-based feedstocks using Pd-catalyzed telomerization of 1,3-butadiene resulted in the development of a highly active catalyst system. A ligand screening was performed, and Pd/tris(2-methoxyphenyl)phosphine (TOMPP) was identified as the most promising catalyst. A solvent- and base-free protocol was developed, which allows efficient and selective conversion of a wide variety of polyol substrates (e.g., glycerol, diols, carbohydrates, and sugar alcohols). In the case of hemi-acetal bearing sugars, catalyst deactivation was observed and mechanistic studies showed that extensive formation of ligand-derived phosphonium species depleted the amount of available ligand. Stoichiometric coordination reactions gave insight into the phosphine alkylation mechanism and demonstrated the reversibility of the observed reaction. A simple and efficient one-pot synthesis method was developed for the preparation of [Pd((1-3,7,8η)-(E)-octa-2,7-dien-1-yl)(PR3)]+ complexes, which are key reactive intermediates. Based on these studies, an extended telomerization mechanism is proposed, which accounts for the formation of ligand-derived phosphonium species and the reversibility of reaction pathways.
Pure and Applied Chemistry is the official monthly Journal of the International Union of Pure and Applied Chemistry (IUPAC), with responsibility for publishing works arising from those international scientific events and projects that are sponsored and undertaken by the Union.