SYNTHESIS AND ANTICONVULSANT ACTIVITY OF NOVEL 1,3,4-OXADIAZOLE DERIVATIVES

2 Oxo-2h-chromene-3-carbohydrazide (1) reacts with various aromatic aldehydes to give corresponding 2-oxo-2h-chromene-3-carbohydrazide arylidene hydrazides (SB1-8). Oxidative cyclization of (SB1-8) with mercuric oxide and iodine in DMF medium furnishes the title compounds 3-(5-aryl-1,3,4-oxadiazol2-yl)-2h-chromen-2-ones (2a-h). All the synthesized compounds were assigned structures on the basis of IR, 1 H-NMR and Mass spectral data. Some of the selected compounds were evaluated for In vivo anticonvulsant activity by MES and PTZ models.

Electrocrystallization and solubility of mercury in alkaline solution

The chemical thermodynamics of mercury in aqueous sodium hydroxide solution has been investigated through electrochemical polarisation and solubility experiments. A review of thermodynamic data allowed determination of the Hg/HgO electrode potential. Cyclic voltammetry revealed a complex anodic reaction beginning with aqueous dissolution of elemental mercury and subsequent electrocrystallization of mercuric oxide. Cathodic sweeps showed dual reduction reactions, attributed to the presence of aqueous mercury and mercuric oxide. The solubility and hence activity of elemental mercury in sodium hydroxide solution was determined, otherwise known as the Sechenov salt effect. Sodium hydroxide salted mercury out of solution.

Comparison of optical-feedback cavity-enhanced absorption spectroscopy and gas chromatography for ground-based and airborne measurements of atmospheric CO concentration

We present the first comparison of carbon monoxide (CO) measurements performed with a portable laser spectrometer that exploits the optical-feedback cavity-enhanced absorption spectroscopy (OF-CEAS) technique, against a high-performance automated gas chromatograph (GC) with a mercuric oxide reduction gas detector (RGD). First, measurements of atmospheric CO mole fraction were continuously collected in a Paris (France) suburb over 1 week. Both instruments showed an excellent agreement within typically 2 ppb (part per billion in volume), fulfilling the World Meteorological Organization (WMO) recommendation for CO inter-laboratory comparison. The compact size and robustness of the OF-CEAS instrument allowed its operation aboard a small aircraft employed for routine tropospheric air analysis over the French Orléans forest area. Direct OF-CEAS real-time CO measurements in tropospheric air were then compared with later analysis of flask samples by the gas chromatograph. Again, a very good agreement was observed. This work establishes that the OF-CEAS laser spectrometer can run unattended at a very high level of sensitivity ( < 1 ppb) and stability without any periodic calibration.