Palladium Nanoparticles Supported on an Organic−Inorganic Fluorinated Hybrid Material. Application to Microwave-Based Heck Reaction

Water-Sculpting of a Heterogeneous Nanoparticle Precatalyst for Mizoroki-Heck Couplings under Aqueous Micellar Catalysis Conditions

Powdery, spherical nanoparticles (NPs) containing ppm levels of palladium ligated by t-Bu₃P, derived from FeCl₃, upon simple exposure to water undergo a remarkable alteration in their morphology leading to nanorods that catalyze Mizoroki-Heck (MH) couplings. Such NP alteration is general, shown to occur with three unrelated phosphine ligand-containing NPs. Each catalyst has been studied using X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), and cryogenic transmission electron microscopy (cryo-TEM) analyses. Couplings that rely specifically on NPs containing t-Bu₃P-ligated Pd occur under aqueous micellar catalysis conditions between room temperature and 45 °C, and show broad substrate scope. Other key features associated with this new technology include low residual Pd in the product, recycling of the aqueous reaction medium, and an associated low E Factor. Synthesis of the precursor to galipinine, a member of the Hancock family of alkaloids, is suggestive of potential industrial applications.

Tunable Dielectric Properties of Poly(vinylidenefluoride-co-hexafluoropropylene) Films with Embedded Fluorinated Barium Strontium Titanate Nanoparticles

Fluoropolymer nanocomposites of poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP) were prepared using fluorinated barium strontium titanate (Ba_1-xSr_xTiO₃, BSTO) nanoparticles (NPs) by low-temperature synthesis using a modified liquid-solid solution process. The exact stoichiometry of as-synthesized BSTO NPs was confirmed by X-ray diffraction analysis along with lattice parameter calculations. The synthesized BSTO NPs were fluorinated using 2,2,2-trifluoroacetic acid as a fluorous ligand. The BSTO NPs showed high solubility in the fluorous system (polymer and solvent) on account of their modified surface. The root-mean-square roughness of the fluorinated BSTO/PVdF-HFP nanocomposite was 76 times lower than that of the nonfluorinated BSTO/PVdF-HFP nanocomposite. The dielectric constant of the fluorinated BSTO/PVdF-HFP nanocomposite exhibited Curie temperature behavior. The dielectric constant of the nanocomposite predicted using the modified Kerner model at room temperature agreed well with the experimental values.

Convenient protocols for Mizoroki-Heck reactions of aromatic bromides and polybromides with fluorous alkenes of the formula H2C[double bond, length as m-dash]CH(CF2)n-1CF3 (n = 8, 10)

The fluorous alkenes H₂C[double bond, length as m-dash]CHR_fn (R_fn = (CF₂)_n-1CF₃; n = 8, 10) undergo the Mizoroki-Heck reaction with a variety of aromatic monobromides and polybromides such as 1,3- and 1,4-C₆H₄Br₂, 1,3,5-C₆H₃Br₃, 1,3,5-C₆H₃Br₂Cl, 1,4-XC₆H₄Br (X = CF₃, R_f8, COCH₃, CN, 1,4-OC₆H₄Br), 1,2-O₂NC₆H₄Br, 5-bromoisoquinoline, 5-bromopyrimidine, 3-bromo-5-methoxypyridine, and 3,5-dibromopyridine (sixteen examples, 78% average isolated yield). Typically, 1.2-2.4 equiv. of alkene are employed per Ar-Br bond, together with Pd(OAc)₂ catalyst (4-5 mol%/Ar-Br bond), n-Bu₄N⁺ Br^- (0.8-1.0 equiv./Ar-Br bond), NaOAc (1.2-2.4 equiv./Ar-Br bond), and 3 : 1 w/w DMF/THF as solvent (120 °C). No effort is necessary to exclude air or moisture, and reactions may be conducted on >10 g scales. Only E isomers of the products Ar(CH[double bond, length as m-dash]CHR_fn)_m are detected. Thirteen representative examples are hydrogenated (Pd/C, balloon pressure H₂), giving Ar(CH₂CH₂R_fn)_m (92% average isolated yield).

In situ generated and stabilized Pd nanoparticles by N2,N4,N6-tridodecyl-1,3,5-triazine-2,4,6-triamine (TDTAT) as a reactive and efficient catalyst for the Suzuki–Miyaura reaction in water

The Suzuki–Miyaura coupling reaction was efficiently catalyzed by the in situ generated and stabilized Pd nanoparticles employing TDTAT in water.

A nitrogen and sulphur functionalized graphene oxide–palladium nanoparticle hybrid catalyst for an efficient Heck coupling

A nanohybrid of Pd on GO functionalized with N and S has been fabricated, and demonstrated as an efficient catalyst for Heck coupling with a substantially low catalytic loading (0.02 mol%).

Immobilized NNN Pd-complex on magnetic nanoparticles: efficient and reusable catalyst for Heck and Sonogashira coupling reactions

A highly efficient and easily recyclable magnetic nanoparticle supported palladium catalyst was developed and applied in the Heck and Sonogashira reactions in order to show its catalytic applicability in Pd-catalyzed C–C coupling protocols.

Synthesis and characterization of functionalized titania-supported Pd catalyst deriving from new orthopalladated complex of benzophenone imine: catalytic activity in the copper-free Sonogashira cross-coupling reactions at low palladium loadings

Efficient catalytic activity of TiO₂-supported Pd catalyst in the copper, amine and phosphine free Sonogashira cross-coupling reactions at low Pd-loadings.

Anthraquinone dyes for superhydrophobic cotton

Water-repellent, self-cleaning and stain resistant textiles are of interest for industrial applications. Anthraquinone reactive dyes were covalently grafted onto cotton fabric surfaces obtaining bright colors with good wash-fastness properties and giving rise to breathable superhydrophobic textiles with self-cleaning properties.

Palladium salt and functional reduced graphene oxide complex: in situ preparation of a generally applicable catalyst for C–C coupling reactions

A simple scheme of Pd²⁺ fixed on FRGO as a highly efficient coupling catalyst.

Investigation of Pd nanoparticles supported on zeolites for hydrogen production from formic acid dehydrogenation

Palladium nanoparticles supported on different BETA zeolites are promising catalysts for H₂production from formic acid dehydrogenation.

Synthesis of new surfactant-like triazine-functionalized ligands for Pd-catalyzed Heck and Sonogashira reactions in water

N ²,N⁴,N⁶-Tridodecyl-1,3,5-triazine-2,4,6-triamine (TDTAT) is introduced as a new surfactant-like triazine-functionalized ligand for the efficient Pd-catalyzed Heck and Sonogashira reactions in water.

A green approach for the decoration of Pd nanoparticles on graphene nanosheets: An in situ process for the reduction of C–C double bonds and a reusable catalyst for the Suzuki cross-coupling reaction

In situ synthesis of Pd nanoparticles on graphene nanosheets with simultaneous reduction of alkene to alkane using hydrogen gas were utilized as efficient catalysts for the Suzuki cross-coupling reaction.

Palladium-phosphorus/sulfur nanoparticles (NPs) decorated on graphene oxide: synthesis using the same precursor for NPs and catalytic applications in Suzuki-Miyaura coupling

PdP2 and Pd4S nanoparticles (NPs) (size: ∼2-6 and 9-15 nm respectively) have been prepared for the first time from a single source precursor complex [Pd(L)Cl2] (1) by its one pot thermolysis at 200 °C in TOP and OA/ODE (1 : 1) respectively. These NPs were stirred with graphene oxide (GO) at room temperature to prepare NP composites, GO-PdP2 and GO-Pd4S. The GO-PdP2 NPs have been synthesized for the first time. The thioether ligand L prepared by reaction of 1,3-dibromo-2-propanol with the in situ generated PhSNa reacts with [PdCl2(CH3CN)2] in CH3CN at 70 °C resulting in 1. The L and 1 have been characterized by (1)H and (13)C{(1)H} NMR and HR-MS. The single crystal structure of 1 determined by X-ray diffraction reveals nearly square planar geometry around the Pd metal centre. The catalytic activities of two palladium nano-phases having phosphorus and sulphur respectively as a co-constituent for Suzuki-Miyaura coupling have been found to be exceptionally different, as PdP2 nanoparticles (NPs) grafted on graphene oxide (GO-PdP2) are significantly more efficient than Pd4S NPs grafted on GO. Without grafting PdP2 and Pd4S both have low efficiency. This is the first report comparing the influence of P and S on the catalytic activity of Pd NPs. TEM, SEM-EDX and powder-XRD have been used to authenticate all NPs. The GO-PdP2 NPs have been found to be efficient catalysts for Suzuki-Miyaura coupling reactions (yield up to 96% in 30 min) at room temperature to 80 °C. Their recyclability has been found up to 6 cycles. In contrast, GO-Pd4S NPs are little active in comparison with GO-PdP2 NPs. The size of NPs and their distribution on GO appear to be key factors affecting the catalytic efficiency of the composite NPs. Leaching of Pd from GO-PdP2 NPs contributes significantly to the catalysis as evidenced by the three phase test, hot-filtration and recycling experiments. The catalysis is almost homogeneous.

Heterogeneous Pd catalysts supported on silica matrices

Features, advantages and limitations associated with palladium catalysts deposited over various siliceous supports in different types of practically useful organic transformations are reviewed.

Efficient heterogeneous catalytic hydrogenation of acetone to isopropanol on semihollow and porous palladium nanocatalyst

Highly efficient and remarkable selective acetone conversion to isopropanol has been achieved via a heterogeneous catalytic hydrogenation of acetone by NaBH4 in the presence of semihollow palladium nanoparticles (PdNPs) grown on ITO substrate. PdNPs with high surface defect grown on an indium tin oxide (ITO) surface were prepared via a simple immersion of the substrate into a solution containing K2PdCl6, sodium dodecyl sulphate (SDS), and formic acid for 2 h at room temperature. The sample showed remarkably high heterogeneous catalytic efficiency by producing 99.8% of isopropanol within 6 min using only 0.28 μg of PdNPs on the ITO surface. The present system exhibits heterogenenous catalytic hydrogenation efficiency 1 × 10(6) time higher than using the conventional Raney Ni system.

Silaphenylmercuric triflate catalyzed reactions: synthesis of a solid-supported mercuric salt catalyst

Let it flow, let it flow: A procedure to generate the first solid-supported mercuric salt, silaphenylmercuric triflate, is described. Silaphenylmercuric triflate showed remarkable catalytic activity for an indole synthesis, furanoyne cyclization, arylyne cyclization, and tandem carbocyclizations. An efficient flow reaction system for indole synthesis and arylyne cyclization is also described (see figure).