XRD and bulk magnetic studies on Ni-Cd and Ti doped Ni-Cd ferrites

For the ferrites Ni _x Cd_1–x Fe₂O₄ (x=0.3, 0.4,1) the lattice parameter, grain size, electrical resistivity, initial permeability, Curie temperature and squareness of the magnetization curve were measured. The results are discussed in terms of the model of the canted spin structure taking into account the domain structure of the polycrystalline ferrite.     

Asymmetric synthesis of (+)-stagonolide C and (−)-aspinolide A via organocatalysis

A new enantioselective synthesis of two important fungal metabolites, (+)-stagonolide C and (?)-aspinolide A, has been described from readily available raw materials. Proline catalyzed asymmetric α-aminooxylation and Jorgensen’s epoxidation of aldehydes are the key reactions employed in the introduction of chirality. The formation of the 10-membered lactone core structure was finally accomplished via Steglich esterification and ring closing metathesis reactions.     

Fully Diastereoselective Synthesis of Polysubstituted,Functionalized Piperidines and Decahydroquinolines Based on Multicomponent Reactions Catalyzed by Cerium(IV) Ammonium Nitrate

The cerium(IV) ammonium nitrate (CAN)‐catalyzed, three‐component reaction between primary amines, β‐dicarbonyl compounds, and α,β‐unsaturated aldehydes in ethanol heated to reflux, constitutes a general, one‐pot synthesis of 1,4‐dihydropyridines. Their reduction with sodium triacetoxyborohydride furnished piperidine derivatives bearing up to five substituents with full diastereoselectivity in a hitherto inaccessible stereochemical arrangement. The reaction proceeded with no significant loss of enantiomeric purity under mild reduction conditions that are compatible with several functional groups that are normally sensitive to reduction. Octahydroquinolin‐5‐one derivatives, which were prepared by a modified version of the initial multicomponent reaction, were not suitable substrates for the sodium triacetoxyborohydride mediated reduction, but they were transformed into the corresponding decahydroquinolines, including a precursor of the amphibian alkaloid pumiliotoxin C, by catalytic hydrogenation under a variety of conditions.     

A Novel Synthesis and Characterization of Titanium Superoxide and its Application in Organic Oxidative Processes

A novel, exceptionally stable titanium superoxide radical ion was prepared and its structure determined by FTIR, ESR, Raman spectroscopy, X-ray diffraction, thermogravimetric/differential thermal analysis and elemental analysis. This heterogeneous catalyst has been found to be effective for the selective oxidation of aromatic amines and phenols to the corresponding nitro aromatics and p-quinones, respectively. In addition, this non-toxic, inexpensive and reusable catalyst has also been used in aminobromination of olefins, which proceed to give the 1, 2-bromoaminated anti-Markovnikov product. A brief account of these results is summarized in this review.     

Ni<Superscript>2+</Superscript>-substituted Mg–Cu–Zn ferrites: a colloidal approach of tuning structural and electromagnetic properties

A robust synthesis approach to Ni²⁺-substituted Mg_0.25-xNi _x Cu_0.25Zn_0.5Fe₂O₄ (0?≤?x?≤?0.25?mol.) ferrimagnetic oxides using citrate assisted sol–gel process is reported. The route utilizes simple metal nitrate precursors in aqueous solution, thus eliminating the need for organometallic precursors. Citric acid acts as a fuel for the combustion reaction and forms stable complexes with metal ions preventing the precipitation of hydroxilated compounds to yield the composite ferrite structure by auto-combustion process. The XRD signatures, especially (3 1 1) plane, confirmed the formation of spinel structure. The linear growth of lattice constant from 8.385 to 8.409?Å was observed by Ni²⁺ substitution from 0 to 0.25. The dense microstructure is observed with the average grain size of 0.42–2.18?µm. The transport properties revealed the semiconducting behavior of as-prepared ferrite material, with an increase in the DC-electrical resistivity by the incorporation of nickel. The magnetic properties viz. initial permeability (µ_i) and magnetic moment (n_B) are explained, based on the deviation in saturation magnetization (M_s), anisotropy constant (K₁)_, density values, and exchange interactions. Furthermore, the effect of adding Ni²⁺ on the Curie temperature, frequency-dependent dielectric properties of the ferrite material are also discussed.

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A concise enantioselective synthesis of (+)-decarestrictine L via proline-catalyzed sequential α-aminooxylation and Horner–Wadsworth–Emmons olefination

A short enantioselective synthesis of (+)-decarestrictine L, a cholesterol biosynthesis inhibitor metabolite, is described using a d-proline catalyzed sequential α-aminooxylation and a Horner–Wadsworth–Emmons olefination.     

NaIO4/KI/NaCl: a new reagent system for iodination of activated aromatics through in situ generation of iodine monochloride

A new reagent system consisting of NaIO₄/KI/NaCl in aq AcOH has been found to be effective in iodinating a variety of activated aromatic substrates via in situ-generated iodine monochloride, to furnish iodoaromatics in excellent yields. This iodination procedure has been applied successfully for a cost-effective synthesis of 3,3′-diaminobenzidine, a key intermediate for preparing proton conducting membranes for fuel cell applications, with high yield and a purity of 99.7%.     

2-Nitrobenzaldehyde Thiocarbohydrazone Assisted Precise Extraction Spectrophotometric Method for the Determination of Ruthenium(III) in Alloy and Catalysts

A simple, rapid, selective, sensitive and reliable extractive spectrophotometric method was developed for the determination of ruthenium(III) using 2-nitrobenzaldehyde thiocarbohydrazone (2-NBATCH) as a chromogenic chelating ligand. The ruthenium(III)?2-NBATCH complex is formed in aqueous acetic acid media (0.7 M) containing an organic solvent after 5 min heating on a water bath. The red colored complex is extracted into 1,2-dichloroethane and absorbance is measured at 445 nm against reagent blank. The Beer’s law is obeyed within 1?6 g/mL of ruthenium(III), the optimum concentration range was 2?5 g/mL of ruthenium(III) evaluated by Ringbom’s plot. Molar absorptivity and Sandell’s sensitivity of complex were 1.41 × 10⁴ L/mol/cm and 0.0075 μg/cm², respectively. The stoichiometry of complex was 1: 3 established from Job’s method of continuous variation, molar ratio method and logarithmic slope method. The proposed method was applied for determination of ruthenium(III) in binary and ternary, synthetic mixtures corresponding to fission product elements alloy and ruthenium(III) catalysts.