Results 1 - 10 of 507
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[en] A simple and efficient method for the synthesis of spiro[4H-pyran-oxindole] derivatives by means of three-component reactions between isatins, malononitrile or ethyl cyano-acetate, and 1,3-dicarbonyl compounds in the presence of catalytic amount of magnesium perchlorate in 50% aqueous ethanol medium has been described
[en] A novel cataluminescence (CTL) sensor was firstly fabricated utilizing α-MoO3 nanobelts as sensing material, which possesses lower working temperature of 120 °C for detection of diethyl ether gas. Under optimal conditions (200 mL min−1, 120 °C, 440 nm), as-made CTL sensor shows a wider detection range of 9.0–2000 ppm with a lower limit of detection of 7.5 ppm. The respond and recovery time were 16 s and within 2 s, respectively. Meanwhile, as-made CTL sensor exhibits an outstanding selectivity towards other 11 interferences. Besides, the highly stable signals were also obtained with the relative standard deviation of 2.60%. In general, α-MoO3 nanobelts as a sensing material have the potential application prospect in CTL sensor for detection of diethyl ether.
[en] (Pyridine)(tetrahydroborato)zinc complex, (Zn(BH4)2(py)), as a stable white solid, was prepared quantitatively by complexation of an equimolar amount of zinc tetrahydroborate and pyridine at room temperature. This reagent can easily reduce variety of carbonyl compounds such as aldehydes, ketones, acyloins, α-diketones and α,β-unsaturated carbonyl compounds to their corresponding alcohols in good to excellent yields. Reduction reactions were performed in ether or THF at room temperature or under reflux conditions. In addition, the chemoselective reduction of aldehydes over ketones was accomplished successfully with this reducing agent
[en] A typical reaction procedure for the preparation is as follows. A 15 mL two-neck round bottom flask equipped with a reflux condenser, a magnetic stirrer bar, a septum and argon tee connected to an argon source was charged with β,β-difluoro-α-phenylvinylstannane (0.100 g, 0.230 mmol), 1,1-difluoro-2-iodo-2-phenylethene (0.136 g, 0.510 mmol) and 5 mL DMF. After Pd(PPh3)4 (0.023 mmol) and CuI (0.023 mmol) were added, the mixture was heated at 80 .deg. C for 2 hours and then quenched with water. The reaction mixture was extracted with diethyl ether (30 mL x 2). The diethyl ether solution was dried with anhydrous MgSO4, filtered, and concentrated under reduced pressure. The residue was purified by silica gel column chromatography
[en] H-clay complexes of Kotli series, Lateritic red earth, red soil adsorbed less phosphate than corresponding H-clays at pH-3-10 while reverse was true in Drab earth, Gujranwala series, Yellow-brown soil at pH-3-6. pH of phosphate adsorption maximum was shifted towards acid side due to organic matter in all samples. Increase or decrease in surface area due to organic matter showed inverse relationship with phosphate. (author)