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Quantitative analysis of the products formed in 1,1′-azoisobutane pyrolyses in the temperature range of 553°–602°K has shown that the major reactions of the iso-butyl radical are Analysis of initial rate data gave log10k4/(kc)1/2(cm?3/2.mol 1/2.sec?1/2) = 7.54±0.44 ? (136.5 + 4.8) kJ/mol/2.303RT, the Arrhenius parameters obtained being in good agreement with thermodynamic data for reaction (4). Measured values of ka/(kc)1/2 where ka is the rate constant of the reaction iC4H9 + AIB → iC4H10 +. AIB were consistent with published parameters determined by photolysis of 1,1′-azoisobutane. Combination of photolysis and pyrolysis data gave log10 ka/(kc)1/2(cm3/2.mol?1/22.sec?1/2) = 3.68 ± 0.15 ? (27.2 ± 1.2) kJ/mol/2.303RT. The crosscombination ratio for methyl and iso-butyl radicals has been found to be 0.25, indicating that the geometric mean rule does not hold for methyl and iso-butyl radicals. 相似文献
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Zheng BS Zhang XY Zhu HW Luo SX Lindoy LF McMurtrie JC Turner P Wei G 《Dalton transactions (Cambridge, England : 2003)》2005,(8):1349-1351
Discrete cobalt(II) and nickel(II) complexes of type ML (where L is a bis(2,4-pentanedionate) derivative incorporating a -SCH2CH2S- bridge between the gamma-carbons of respective beta-diketone units) have been synthesised and represent the first examples in which a gamma-substituted, thioether-containing beta-diketone ligand coordinates via a sulfur and oxygen donor in preference to the classical coordination mode involving both beta-diketonate oxygens. 相似文献
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A general method has been developed for the synthesis of N-substituted oxindoles. The two-step process involves initial microwave-assisted amide bond formation between 2-halo-arylacetic acids and various alkylamines and anilines, followed by a palladium-catalyzed intramolecular amidation under aqueous conditions. In the case of alkylamines, the procedure can be carried out as a one-pot process without isolation of the intermediate amide. [structure: see text] 相似文献
109.
Single-mode plane-polarized ytterbium-doped large-core fiber laser with 633-W continuous-wave output power 总被引:3,自引:0,他引:3
Jeong Y Nilsson J Sahu JK Soh DB Dupriez P Codemard CA Baek S Payne DN Horley R Alvarez-Chavez JA Turner PW 《Optics letters》2005,30(9):955-957
We demonstrate a cladding-pumped single-mode plane-polarized ytterbium-doped fiber laser generating 633 W of continuous-wave output power at 1.1 microm with 67% slope efficiency and a polarization extinction ratio better than 16 dB. The laser is end pumped through both fiber ends and shows no evidence of roll-over, even at the highest output power, which is limited only by the available pump power. 相似文献
110.
Single-frequency, single-mode, plane-polarized ytterbium-doped fiber master oscillator power amplifier source with 264 W of output power 总被引:10,自引:0,他引:10
Jeong Y Nilsson J Sahu JK Soh DB Alegria C Dupriez P Codemard CA Payne DN Horley R Hickey LM Wanzcyk L Chryssou CE Alvarez-Chavez JA Turner PW 《Optics letters》2005,30(5):459-461
We present a single-frequency, single-mode, plane-polarized ytterbium-doped all-fiber master oscillator power amplifier source at 1060 nm generating 264 W of continuous-wave output power. The final-stage amplifier operated with a high gain of 19 dB and a high conversion efficiency of 68%. There was no evidence of rollover from stimulated Brillouin scattering even at the highest output power, and the maximum output was limited only by the available pump power. 相似文献