A synthesis of a-acyloxyamides is described which utilizes the reaction of 7-picoline N-oxide and various organic acids with diphenylketene N-p-tolylimine. 相似文献
Very low pressure photolysis (VLPØ) of chlorine nitrate was performed in a quartz Knudsen cell. The light source was a 2500 W high-pressure xenon lamp, and a modulated molecular-beam mass spectrometer was used to monitor the concentration of ClONO2 and photolysis products. Because of the low pressures used (? 10?3 torr) and the short residence time in the cell (≈1 s), secondary reactions were unimportant and the primary products could be directly identified. The primary photolysis products (λ ≈ 2700 Å) are atomic chlorine and NO3 free radical. Chlorine atoms were identified both by the appearance of Cl2 (wall recombination product; the walls were not poisoned) and by HCl produced when C2H6 was added to the cell. Nitrate free radical was directly identified as a mass peak at m/e = 62, as well as by chemical titration with nitric oxide: NO3 + NO → 2NO2. It was verified by direct tests that the peak at m/e = 62 did not arise from possible HNO3 contamination or from N2O5, a possible secondary product. This titration reaction was used to measure quantitatively a lower limit to the primary quantum yield, φ ? 0.5 ± 0.3. This represents a lower limit because of the unknown extent of the secondary photolysis of NO3 under our conditions. We believe this to be the first observation using mass spectrometry of the NO3 free radical. The quantum yield for atomic chlorine is φ = 1.0 ± 0.2. N2O was used to test for O(1D) according to the reaction, O(1D) + N2O → products; none was observed. Triplet oxygen, O(3P) was observed to the extent of ≈ 10% by the reaction O(3P) + NO2 → NO + O2, but this yield can also be due to the photolysis of NO3 free radical produced in the primary step. We conclude that the predominant reaction pathway is . 相似文献
Summary A semi-continuous, counter-current chromatographic refiner (SCCR) was packed with an anion resin in the bisulphite form and used to separate mixtures of sugars from different feedstocks. Products with purities of more than 99% were achieved and solid concentrations of the fructose products of 12% w/v were possible. The deterioration of the anion resin was controlled by simple precautions and thus its useful life was substantially prolonged. 相似文献
Summary Equipment which has been used or suggested for preparative scale chromatography is reviewed. Particular attention is paid to one form of equipment for continuous counter-current chromatography which employs a moving mechanical seal. The theoretical effects of practical operating conditions and the mode of operation of this equipment are discussed. The influence of these effects on polymer fractionation is also considered. A theoretical model, based on the equilibrium stage concept, is proposed for the simulation of continuous gel permeation chromatography of a binary feed on such an apparatus. Examples of the results obtained from the computer simulation are given. 相似文献