Quinolinium Dichromate Oxidation of Aliphatic Aldehydes: A Kinetic Study

Kinetic data on the rates of quinolinium dichromate oxidation of a series of aliphatic aldehydes have been determined and discussed with reference to aldehyde hydration equilibria. Kinetic results support a pathway proceeding via a rate-determining oxidative decomposition of a chromate ester of an aldehyde hydrate. A cyclic transition state is suggested; being a Hückel-type system (4n + 2), this would be an allowed process. The deuterium isotope effect for the oxidation of acetaldehyde (kH / kD = 6.4) indicated a carbon-hydrogen cleavage rather than a carbon-carbon cleavage

Kinetics of Oxidation of Heterocyclic Compounds by Quinolinium Dichromate

Quinolinium dichromate in sulfuric acid oxidized heterocyclic aldehydes (to the corresponding acids) and heterocyclic carboxylic acids (to the corresponding hydroxy-substituted acids) in acetic acidwater medium (vol. ratio, v(water)/v(acetic acid) = 50:50). The kinetic results supported a mechanistic pathway proceeding via a rate-determining decomposition of the chromate ester

Kinetics of Oxidation of Heterocyclic Compounds by Quinolinium Dichromate

Quinolinium dichromate in sulfuric acid oxidized heterocyclic aldehydes (to the corresponding acids) and heterocyclic carboxylic acids (to the corresponding hydroxy-substituted acids) in acetic acidwater medium (vol. ratio, v(water)/v(acetic acid) = 50:50). The kinetic results supported a mechanistic pathway proceeding via a rate-determining decomposition of the chromate ester

Synthesis and Piezoelectric Response of Cubic and Spherical LiNbO3 Nanocrystals

Methods have been developed for the shape-selective synthesis of ferroelectric LiNbO3 nanoparticles. Decomposition of the single-source precursor, LiNb(O-Et)6, in the absence of surfactants, can reproducibly lead to either cube- or sphere-like nanoparticles. X-Ray diffraction shows that the LiNbO3 nanoparticles are rhombohedral (R3c). Sample properties were examined by piezoresponse force microscopy (PFM) and Raman where both sets of nanoparticles exhibit ferroelectricity. The longitudinal piezoelectric coefficients, d33, varied with shape where the largest value was exhibited in the nanocubes (17 pm V21 for the cubes versus 12 pm V21 for spheres)

Structural phase transition and ferromagnetism in monodisperse 3 nm FePt particles

FePt nanoparticles with a size of 3 nm and thermally stable room-temperature ferromagnetism are investigated. The monodisperse nanoparticles were prepared by chemical synthesis and a salt-matrix annealing technique. Structural and magnetic characterizations confirmed the phase transition from the disordered face-centered cubic structure to the L10 structure with the chemical ordering parameter of 0.62±0.05. Analysis in blocking temperature and fitting of temperature dependence of switching field reveals that the transformed 3 nm nanoparticles have a magnetic anisotropy constant of (2.8±0.2) x 106 J/m3, smaller than those for the bigger particles and the fully ordered L10 bulk phase

Fabrication of Nanopeapods: Scrolling of Niobate Nanosheets for Magnetic Nanoparticle Chain Encapsulation

Scrolling of niobate nanosheets (NSs) in the presence of magnetic nanoparticle (NP) chains can lead to peapodlike structures. Surface functional groups on both the NSs and NPs are important in directing the assembly and subsequent NS convolution. The dimensions of the peapods are typically dictated by the diameters of the NPs and the length of the NP chains