Catalytic performance of [Bmim][Co(CO)4] functional ionic liquids for preparation of 1,3-propanediol by coupling of hydroesterification-hydrogenation from ethylene oxide

In this paper, synthesis of 1,3-propanediol (1,3-PDO) through coupling of hydroesterification-hydrogenation from ethylene oxide (EO) catalyzed by 1-butyl-3-methylimidazolium cobalt tetracarbonyl [Bmim][Co(CO)4] functional ionic liquid which was prepared by metathesis reaction between [Bmim]Cl and KCo(CO)4 has been studied. The structure of [Bmim][Co(CO)4] was characterized by FT-IR and 1H NMR. Using [Bmim][Co(CO)4] as catalyst and [Bmim]PF6 as solvent, 1,3-PDO was prepared for the first time by coupling of hydroesterifaction of EO and hydrogenation of methyl 3-hydroxypropionate (3-HPM). The yield of 3-HPM can reach 90.8%, while the yield of 1,3-PDO up to 82.9%. The catalyst can be separated from the product mixture by extraction with deionized water and recycled several times without significant loss of catalytic efficiency. A possible reaction mechanism has also been proposed.

Graphical abstract1-Butyl-3-methylimidazolium cobalt tetracarbonyl [Bmim][Co(CO)4] functional ionic liquid was prepared by metathesis reaction between [Bmim]Cl and KCo(CO)4. Using [Bmim][Co(CO)4] as catalyst and [Bmim]PF6 as solvent, 1,3-propanediol was prepared by hydrogenation of the intermediate methyl 3-hydroxypropionate which was synthesized by hydroesterification of ethylene oxideFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Catalytic performance of [Bmim][Co(CO)4] was first studied. ► 1,3-PDO was prepared by coupling of hydroesterifaction-hydrogenation of EO. ► The catalyst system can be recoverable and recycled several times. ► A possible reaction mechanism has also been proposed for the first time.