Polymeric Ruthenium Porphyrin-Functionalized Carbon Nanotubes and Graphene for Levulinic Ester Transformations into ?-Valerolactone and Pyrrolidone Derivatives.

ABSTRACT: Polymeric ruthenium porphyrin-functionalized carbon nanotubes (Ru-PP/CNTs) were prepared by the metallation of polymeric porphyrin-functionalized carbon nanotubes (PP/CNTs) with Ru₃(CO)₁₂, whereas PP/CNTs were obtained by the condensation of terephthaldehyde and pyrrole in the presence of CNTs. The Ru-PP/CNTs have a thin layer of highly cross-linked polymeric ruthenium porphyrin coating over the CNT surface via strong ?-? stacking interactions, thus showing a bilayered structure with an amorphous polymeric outer surface and an internal CNT core. Polymeric ruthenium porphyrin-functionalized reduced graphene oxide (Ru-PP/RGO) was prepared with a synthetic procedure similar to Ru-PP/CNTs, with RGO as the internal core. Both Ru-PP/CNTs and Ru-PP/RGO showed excellent catalytic performance toward hydrogenation of biomass-related ethyl levulinate (EL) to ?-valerolactone (GVL) with Ru-centered porphyrin units as the catalytic active species. Under optimized reaction conditions, a GVL yield higher than 99% with a complete conversion of EL was observed over both Ru-PP/CNTs and Ru-PP/RGO. In addition to GVL preparation, the versatile Ru-PP/CNTs can efficiently promote reductive amination of EL with various amines for the synthesis of pyrrolidone derivatives, with the corresponding yields ranging from 96.3 to 88.7%. Moreover, the composite materials of both Ru-PP/CNTs and Ru-PP/RGO behave as heterogeneous catalysts in the reaction system and can be easily reused.

SUBMITTER: Zhang T 

PROVIDER: S-EPMC6641044 | biostudies-literature | 2017 Jul

REPOSITORIES: biostudies-literature