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Substrate Loss (substrate + loss)
Selected AbstractsSolvolysis of Some Arenediazonium Salts in Binary EtOH/H2O Mixtures under Acidic ConditionsEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 17 2003Román Pazo-Llorente Abstract We have determined the product distribution, the rate constants for dediazoniation product formation, and the solvolytic rate constants for 2-, 3-, and 4-methylbenzenediazonium ions (2-, 3-, and 4-MBD, respectively) loss in acidic ethanol/water mixtures over the whole composition range by a combination of spectrophotometric (UV/Vis) and high performance liquid chromatography (HPLC) measurements. The observed rate constants (kobs) for substrate loss are equal to those for product formation, and they remain essentially constant (2-MBD) with changing solvent composition but increase by a factor of ,2 (4MBD) on going from water to 100% EtOH. Up to four dediazoniation products , cresols (ArOH), chlorotoluene (ArCl), methylphenetole (ArOEt), and toluene (ArH) , were detected, depending on the solvent composition; the major dediazoniation products were the ArOH and ArOEt derivatives. The product selectivity (S) of the reaction towards nucleophiles is low and essentially constant with changing solvent composition, and good linear correlations between log kobs and YCl (solvent ionizing power) were observed for the three ArN2+ ions. All data are consistent with the rate-determining formation of an aryl cation, which reacts immediately with available nucleophiles. The data suggest that the distribution of neutral and anionic nucleophiles in the neighborhood of the ground state arenediazonium ion remains essentially unchanged upon dediazoniation, the observed product distribution reflecting the concentrations of nucleophiles in their immediate environment (i.e., in the first solvation shells of the arenediazonium ions). (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source] Butanolysis of 2-methylbenzenediazonium ions: product distribution, rate constants of product formation, and activation parametersJOURNAL OF PHYSICAL ORGANIC CHEMISTRY, Issue 5 2009M. José Pastoriza-Gallego Abstract We have determined the product distributions, the rate constants of product formation and substrate loss, and the activation parameters for the butanolysis of 2-methylbenzenediazonium, 2MBD, tetrafluoroborate in aqueous 1-Butanol (BuOH) solutions by combining UV,VIS spectroscopy, high performance liquid chromatography (HPLC), and a derivatization protocol that traps unreacted 2MBD as a stable azo dye. BuOH/H2O solutions are miscible over a narrow composition range, but in reverse micelles composed of sodium dodecyl sulfate, SDS, BuOH, and water, are miscible between 45,80%. Two major and two minor dediazoniation products are observed, 2-cresol, ArOH, 2-butyl-tolyl-ether, ArOBu, and small amounts of 2-chlorobenzene, ArCl (from HCl added to control solution acidity) and toluene, ArH (a reduction product). Product yields depend on experimental conditions, but quantitative conversion to products is achieved over the entire composition ranges investigated. The observed rate constants, kobs, obtained by monitoring 2MBD loss or by monitoring ArOH or ArOBu formation, are the same and they are only modestly affected by changes in the solution composition. The activation parameters obtained from the effect of temperature on kobs show that the enthalpy of activation is relatively high compared to those found in bimolecular reactions and the entropy of activation is small but positive. The results suggest that 2MBD is mainly sampling in the BuOH-H2O rich interfacial region of the reverse micelle and are consistent with 2MBD decomposing through a DN,+,AN mechanism, i.e., a rate limiting formation of an aryl cation that reacts immediately with nucleophiles. Copyright © 2008 John Wiley & Sons, Ltd. [source] Design and implementation of a high-performance V-band CMOS bandpass filterMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 2 2010Jin-Fa Chang Abstract In this article, we demonstrate a low-insertion-loss V-band (50,75 GHz) bandpass filter with two finite transmission zeros by standard 0.13 ,m CMOS technology. The proposed filter architecture has the following feature: the low-frequency transmission-zero and the high-frequency transmission-zero can be tuned by the series-feedback capacitor Cs and the parallel-feedback capacitor Cp, respectively. Besides, low-insertion-loss is achieved by adopting thick microstrip-line (MSL) with optimized ground-plane pattern as the needed inductors to minimize the metal and substrate loss. This filter achieved insertion-loss (1/S21) lower than 3 dB over the frequency range of 52.2,76.7 GHz, input return loss (S11) better than ,10 dB over the frequency range of 50.2,80.6 GHz, and output return loss (S22) better than ,10 dB over the frequency range of 50.2,77.3 GHz. The minimum insertion-loss was 2.18 dB at 63.5 GHz, an excellent result for a V-band CMOS bandpass filter. The chip area was only 0.466 × 0.307 mm2, i.e., 0.143 mm2, excluding the test pads. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 309,316, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24935 [source] Micromachined CMOS E-band bandpass coplanar filtersMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 12 2008Pen-Li Huang Abstract In this work, E-band CMOS coplanar filters, whose initial design is made according to quasi- TEM-approximation-based analytical models, are implemented. To study the substrate effects, the CMOS-compatible inductively coupled-plasma (ICP) deep trench technology is used to selectively remove the silicon underneath the filter completely. For the filter with top metal thickness of 0.93 ,m after the backside ICP etching, the results show that the input matching bandwidth, i.e. S11 below ,10 dB, moves from lower 39.8,81.4 GHz-band to higher 55.9,94.1 GHz-band, and the 3-dB bandwidth of S21 moves from lower 43.5,76.3 GHz-band to higher 54.5,93.3 GHz-band. In addition, a 4.67 dB improvement [from ,8.86 dB (at 58.5 GHz) to ,4.19 dB (at 74.5 GHz)] in peak S21 was achieved. These results show that for the design of passive coplanar devices in the E-band, the quasi-TEM- approximation-based analytical models can be used and the backside ICP etching is effective to reduce the substrate loss and parasitic capacitance. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 3123,3125, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23873 [source] Size reduction of microwave and millimeter-wave passive circuits by UC-PBG in standard 0.18-,m CMOS technologyMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 9 2008Shuiyang Lin Abstract Size reduction of microwave and millimeter-wave (mm-wave) passive circuits incorporating a defective uniplanar compact photonic bandgap (UC-PBG) slow-wave structure is investigated. Benefited from the multilayer mental technology of the standard 0.18-,m CMOS process, thin film microstrip structure is properly constructed on the lossy silicon substrate to reduce substrate loss. Defected periodic patterns on the ground plane are used to contribute to an enhancement of the effective dielectric constant and the slow-wave factor is 14% increased by the use of UC-PBG ground. Microwave and mm-wave passive circuits including resonator and filter are designed and fabricated. Measured results show that the use of UC-PBG ground has induced a frequency drop of 14% and validate the size reduction concept by using UC-PBG. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2251,2254, 2008; Published online in Wiley InterScience (www.interscience.wiley.com).DOI 10.1002/mop.23643 [source] | ||||||||||