Influence of surfactant on the morphology and supercapacitive behavior of SILAR-deposited polyaniline thin films

Ionics - Polyaniline thin films have been prepared by the simple and inexpensive successive ionic layer adsorption and reaction (SILAR) method at room temperature in the presence of three different...     

Potential and limitations of nucleon transfer experiments with radioactive beams at REX-ISOLDE

As a tool for studying the structure of nuclei far off stability the technique of γ-ray spectroscopy after low-energy single-nucleon transfer reactions with radioactive nuclear beams in inverse kinematics was investigated. Modules of the MINIBALL germanium array and a thin position-sensitive parallel plate avalanche counter (PPAC) to be employed in future experiments at REX-ISOLDE were used in a test experiment performed with a stable ³⁶S beam on deuteron and ⁹Be targets. It is demonstrated that the Doppler broadening of γ lines detected by the MINIBALL modules is considerably reduced by exploiting their segmentation, and that for beam intensities up to 10⁶ particles/s the PPAC positioned around zero degrees with respect to the beam axis allows not only to significantly reduce the γ background by requiring coincidences with the transfer products but also to control the beam and its intensity by single particle counting. The predicted large neutron pickup cross-sections of neutron-rich light nuclei on ²H and ⁹Be targets at REX-ISOLDE energies of 2.2 MeV ^. A are confirmed. Received: 9 October 2000 / Accepted: 28 January 2001     

Silicon-based thiourea-mediated and microwave-assisted thio-Michael addition under solvent-free reaction conditions

Silicon-based thiourea (SiliaBond® Thiourea) (Si-THU), a heterogeneous catalyst, has been applied to the highly selective C-S bond formation via Michael addition of thiols to α,β-unsaturated carbonyl compounds under solvent-free conditions at 55–60°C. The thio-Michael addition products were obtained in an excellent yield under optimised conditions. This methodology involving a metal-free as well as a metal scavenger catalyst has been found to be an alternative method for the thio-Michael addition reaction.     

NO-NSAIDs. Part 3: nitric oxide-releasing prodrugs of non-steroidal anti-inflammatory drugs

In continuation of our efforts to discover novel nitric oxide-releasing non-steroidal anti-inflammatory drugs (NO-NSAIDs) as potentially "Safe NSAIDs," we report herein the design, synthesis and evaluation of 21 new NO-NSAIDs of commonly used NSAIDs such as aspirin, diclofenac, naproxen, flurbiprofen, ketoprofen, sulindac, ibuprofen and indomethacin. These prodrugs have NO-releasing disulfide linker attached to a parent NSAID via linkages such as an ester (compounds 9-16), a double ester (compounds 17-24), an imide (compounds 25-30) or an amide (compounds 31-33). Among these NO-NSAIDs, the ester-containing NO-aspirin (9), NO-diclofenac (10), NO-naproxen (11), and the imide-containing NO-aspirin (25), NO-flurbiprofen (27) and NO-ketoprofen (28) have shown promising oral absorption, anti-inflammatory activity and NO-releasing property, and also protected rats from NSAID-induced gastric damage. NO-aspirin compound 25, on further co-evaluation with aspirin at equimolar doses, exhibited comparable dose-dependent pharmacokinetics, inhibition of gastric mucosal prostaglandin E(2) (PGE(2)) synthesis and analgesic properties to those of aspirin, but retained its gastric-sparing properties even after doubling its oral dose. These promising NO-NSAIDs could therefore represent a new class of potentially "Safe NSAIDs" for the treatment of arthritic pain and inflammation.     

Regioselective O-alkylation: synthesis of 1-{2-[(2-chloroquinolin-3-yl)methoxy]-6-chloro-4-phenylquinolin-3-yl}ethanones

An efficient and regioselective O-alkylation of amides with a variety of electrophiles in the presence of silver nanoparticles is reported as part of our recent research on building blocks for synthesis of natural products. The nano-silver catalyst initiates O-alkylation of the amides by heteroalkyl halides. Reaction of equimolar 3-acetyl-6-chloro-4-phenylquinolin-2(1H)-one and 2-chloro-3-(chloromethyl)quinolines in the presence of silver nanoparticles in DMSO solution under reflux condition leads to the formation of 1-{1-[2-chloroquinolin-3-yl)methoxy]-6-chloro-4-phenylquinolin-3-yl}ethanones.     

Simple Synthesis of 7‐Formyl‐indole

A simple route to 7‐formyl‐indole (5) is described in which appropriately functionalized o‐nitrotoluenes (1) are converted to 7‐hydroxymethyl‐indole (4) using the Batcho–Leimgruber process. Condensation of 3‐methyl‐2‐nitrobenzyl alcohol (1a) with N,N‐dimethylformamide dimethyl acetal yields the enamine 2a, which upon catalytic hydrogenation affords 4 in 22% yield. When the hydroxyl function in 1 is protected with pivaloyl or tetrahydropyranyl group, the yields of 4 are increased to 39% and 48%, respectively. Finally, 4 is oxidized with pyridinium chlorochromate (PCC) to afford 5 in 86% yield.     

Oxidation of SO2 to sulfate in sea salt aerosols

Summary In laboratory-scale experiments sea salt particles are exposed to SO₂ at a temperature of 22°C and relative humidities of 40, 60 and 80%; the SO₂ gas concentration is fixed to 0.2, 0.5 and 1.0 ppm (v), respectively. In further test series NO₂ is added to the gas phase. As kinetic data the capacity values of the sea salt particles (mg formed sulfate/g dry aerosol) are determined as function of time and from this the reaction rates (mg formed sulfate/g dry aerosol and minute) are calculated in dependence of the yield. The relative humidity (r.h.) has proved to be a decisive reaction parameter. For example, the rate (at a reaction time of one hour) increases at a SO₂ concentration of 0.5 ppm (v) from 0.01 to approx. 0.1 mg SO ₄ ^2– /g·min, if the r.h. will increase from 40 to 80%. However, the gas concentration has only an importance at high humidities (where the reaction takes place in droplets) for the sulfate formation in sea salt aerosols. If the SO₂ concentration is reduced from 1.0 to 0.2 ppm (v) at a r.h. of 80%, the rate will be decreased from 0.2 to about 0.07 mg SO ₄ ^2– /g·min; however, at a r.h. of 60% from 0.075 to 0.04 mg SO ₄ ^2– /g·min. As an increased sulfate formation but no nitrate formation can be detected when NO₂ is added to the gas phase, it can be assumed that SO₂ is oxidized in the electrolyte layer around the sea salt particles whereas NO₂ is reduced. If NO₂ (SO₂:NO₂=1:1) is added to the gas phase, the rate — for example at a r.h. of 40% — will be increased from 0.01 to 0.24 mg SO ₄ ^2– /g·min.