title: Synthesis of Pd(0) nanocatalyst using lignin in water for the Mizoroki-Heck reaction under solvent-free conditions.
abstract: Palladium(0) nanospheres with an average size of 1-5 nm were synthesized and stabilized by lignin in water without any reducing agent. The lignin supported palladium(0) nanoparticles (lignin@Pd-NPs) were characterized by UV-vis., FT-IR, SEM, TEM, HRICP-AES, EDX and PXRD. Absence of the peak at 430 nm in UV-vis., spectrum confirmed the reduction of Pd(II) to Pd(0). The five characteristic peaks at (111), (200), (220), (311) and (222) corresponding to the 2θ values 40°, 46.7°, 67.9°, 81.9° and 86.9°, respectively, appeared in PXRD spectrum indicated the crystallographic planes of Pd(0) with fcc structure. The Pd(0) loaded on lignin was 0.0467 mmol/g determined by HRICP-AES and 0.89% (w/w) by EDX. The performance of lignin@Pd-NPs catalyst have been investigated for the Mizoroki-Heck CC bond formation reactions between n-butyl propene-2-enoate and halobenzenes and substituted halobenzenes in polar to highly polar solvents as well as under solvent-free conditions in the presence of organic or inorganic bases. The lignin@Pd-NPs was found to be a highly efficient catalyst to yield the desired products of up to 94% under solvent-free conditions in short reaction times. The catalyst was heterogeneous and hence recovered by filtration and reused several times in the subsequent batches of the same reaction.
authors.affiliation: Department of Chemistry, University College of Science, Tumkur University, Tumkur, Karnataka 572103, India.
authors.forename: M B
authors.initials: MB
authors.lastname: Marulasiddeshwara
authors.affiliation: Department of Chemistry, University College of Science, Tumkur University, Tumkur, Karnataka 572103, India. Electronic address: raghukp1@gmail.com.
authors.forename: P Raghavendra
authors.initials: PR
authors.lastname: Kumar
mesh_terms: D060326:Chemistry Techniques, Synthetic; D008031:Lignin / Q000737:chemistry*; D053768:Metal Nanoparticles / Q000737:chemistry*; D036103:Nanotechnology; D010165:Palladium / Q000737:chemistry*; D012997:Solvents / Q000737:chemistry*; D014867:Water / Q000737:chemistry*
chemical_list: D012997:Solvents; D014867:Water; D010165:Palladium; D008031:Lignin
keywords: Lignin; Mizoroki–Heck reaction; Nanocatalyst; Palladium