Mild and efficient iodination of aromatic and heterocyclic compounds with the NaClO2/NaI/HCl system

NaClO₂/NaI in the presence of HCl is a mild, cheap, and non-toxic reagent for the iodination of phenols, including estradiol and naphthol, aromatic amines, and heterocyclic substrates, e.g., indoles, 8-hydroxyquinoline, imidazole, in fair to excellent yields by a very simple isolation protocol. The scope of the procedure is exemplified by the first iodination of 5-nitroindole to 3-iodo-5-nitroindole in 75% yield.     

Antioxidant capacity and antibacterial activity from Annona cherimola phytochemicals by ultrasound-assisted extraction and its comparison to conventional methods

In recent years, the food, pharmacy, and cosmetic industries have focused on the search of natural compounds with antimicrobial and antioxidant properties; commonly, these compounds are obtained from Kingdom plantae. The aim of the present work is comparing antibacterial and antioxidant capacity of Annona cherimola Mill leaves, using different extraction methods. The ultrasound assisted extraction technique (UAE) was compared with conventional techniques: Soxhlet and maceration. Water and ethanol were used as solvents for leaves extractions performed with these three methods. The main acetogenins reported in Annona cherimola Mill and Annona muricata L. species were simulated using the functional hybrid B3LYP and to confirm its presence, analysis of the compound composition was performed using FT-IR, UV–Vis and HPLC. Total phenolics (TP) and flavonoids (TF) were determined by spectroscopy techniques and novel Differential Pulse Voltammetry (DPV) electrochemical technique. Total Antioxidant Capacity (TAC) of the extracts was measured, using the DPPH, FRAP and CUPRAC techniques. The highest antioxidant content was found in the Soxhlet water extracts; even so, the UAE technique presented an attractive alternative due to considerable reduction in extraction time, which was greater than 99%, and possible selectivity in compounds extraction. Finally, antibacterial activity of the extracts was evaluated, obtaining the best results against gram-positive bacteria using UAE water extract. In this way, the UAE technique presents an excellent extraction option due to the considerable reduction in time and energy, as well as the increase in antibacterial activity.     

On-line Method for Montelukast Determination in Bile Salt Medium with Multivariate Optimization and Fluorescent Detection

Journal of Analytical Chemistry - The present development involved a flow injection strategy using a mini-column of multiwalled carbon nanotubes and fluorescent detection (λex of 283 nm,...     

Effect of UV radiation on some polymeric networks based on vinyl ester resin and modified lignin

Some semi-interpenetrating polymer networks (semi-IPNs) based on vinyl ester resin (VER) and ammonium lignosulfonate (ALS) modified lignin were synthesized and characterized using Fourier transform-infrared (FT-IR) spectroscopy, optical microscopy (OM) and differential scanning calorimetry (DSC) techniques. VER was synthesized starting from an epoxy resin in reaction with acrylic acid. The cross-linking reaction was initiated by UV radiation. The synthesized networks showed good compatibility, due to some possible interactions between the functional groups from VER and ALS components (OH, especially). A slight effect of photostabilization of the VER was noticed, due to the ALS structures which were incorporated into the resin matrix.     

A Note on Toeplitz Operators in Schatten-Herz Classes Associated with Rearrangement-invariant Spaces

In recent papers, B. Choe, H. Koo, K. Na (see [3]) and Loaiza, M. Lopez-Garcia e S. Perez-Esteva (see [5]) studied conditions in order to a Toeplitz operator, acting on the harmonic Bergman space over the unit ball in and on analytic Bergman space on the unit disk in the complex plane, respectively, belong to the so-called Schaten-Herz class. The purpose of this note is to prove necessary and sufficient conditions in order to a Toeplitz operator T _μ with positive symbol, acting on the harmonic Bergman space on the unit ball in belong to a Schatten-Herz class S ^F _E , associated with a pair of rearrangement invariant sequence spaces E and F. The conditions involve the Berezin transform of its symbol and the average function. on some euclidian discs. The main point is the characterization of Toeplitz operators, that belong to Schatten ideals S _E associated with an arbitrary rearrangement invariant sequence space E.      

Weak-type inequalities for higher order Riesz-Laguerre transforms

In this paper we study the weak-type (1,1) boundedness of the higher order Riesz-Laguerre transforms associated with the Laguerre polynomials. In particular, we obtain the boundedness for the Riesz-Laguerre transforms of order 2 and we find also the sharp polynomial weight ω that makes the Riesz-Laguerre transforms of order greater than two continuous from into L1,∞(dμα), being μα the Laguerre measure.