Preparation and catalytic performance of quaternary ammonium base resin for methanolysis of natural phosphatidylcholine

Received 1 August 2015; Revised 23 November 2015; Accepted 26 November 2015The most acceptable method for preparing glycerophosphocholine is to hydrolyse the natural phosphatidylcholine and use the quaternary ammonium base resin, as a promising heterogeneous catalyst can simplify the craft and minimise the problems existing in the homogeneous catalytic process. However, most of the resins reported in the literature are commercial trimethyl benzyl ammonium base resins and the application of other longer carbon-chain quaternary ammonium resins has not been reported. In the present work, a series of quaternary ammonium base resins were prepared from chloromethyl polystyrene microspheres and different tertiary amines and were used to prepare glycerophosphocholine from natural phosphatidylcholine. The factors affecting the exchange capacity and activity of the resin were investigated. The results showed that the resin possessed a better activity and stability under the following conditions: 1,4-dioxane as solvent, triethylamine as amination agent, reaction temperature of 60°C and amination time of 3 h; it was then used in the methanolysis of phosphatidylcholine by ultrasound-assisted reaction at ambient temperature, with the conversion of phosphatidylcholine attaining 97 % after 4 h. The catalyst was easy to separate from the reaction mixture and could also be readily available for repeat use; the activity and stability were largely consistent after six repeat uses.

Light-promoted catalytic hydrogenation of olefins with nickel complexes: the formation of nickel hydrides from the reaction of Ni(I) complexes with hydrogen

The conditions pertaining to triplet excited state ketone-sensitized photoreduction of Ni(acac)2 under hydrogen were shown to serve as a method for light-promoted hydrogenation of olefins with clean chemospecificity. For example, the double bond in the bicyclic system was preferentially hydrogenated over the other double bond in dicyclopentadiene and in 5-methylenebicyclo-[2.2.1]heptene. This photohydrogenation could be run under a wide range of conditions and was apparently a homogeneous catalytic process; in a late stage of photohydrogenation, concurrence of heterogeneous catalytic processes was not ruled out. The Ni(I) complexes of tetrahydrofuran and olefins generated from the photoreduction of Ni(acac)2 were shown to react with hydrogen to give nickel hydride complexes. By analogy with the generally accepted reaction pattern, coordinated olefins in these nickel hydride complexes probably spontaneously undergo intramolecular addition to give Ni–alkyl complexes. It is suggested that these Ni–alkyl complexes are photoexcited to generate a vacant coordination site so that the reaction with hydrogen can proceed to give products and regenerate a nickel hydride catalyst.