二茂铁及其胺甲基类取代衍生物的紫外光解自由基的研究

本文用自旋捕捉-ESR技术研究了二茂戊铁、环二烯和胺甲基类取代二茂铁的紫外光解过程中的活泼自由基。结果表明,二茂铁光解初级过程中生成的自由基为(C_5H_5Fe)·和C_5H_5·,其衍生物光解则生成(C_5H_5Fe)·和RC_5H_4·,而(C_5H_5Fe)·还可以进一步分解给出C_5H_5和Fe。     

Characterization of the Effects of Vanadium Traps in Cracking Catalysts by Imaging Secondary Ion Mass Spectrometry and Microactivity Test

The vanadium trapping effect of Mg and La containing additives in cracking catalyst contaminated with 2300 ppm Ni and 4700 ppm V has been analyzed by microactivity test (MAT) and imaging secondary ion mass spectrometry (SIMS). The results of SIMS imaging are consistent with cracking activity data and show that the La/spinel is a superior vanadium trap for the fluid catalytic cracking of hydrocarbons (FCC) operation. La/spinel serves as a dual function additive for both vanadium trap and SO_x removal. The optimum amount of La/spinel added to the cracking catalyst is about 15% by weight. This results in an increased catalytic activity, an increase in gasoline yield, and a decrease in coke and gas factors. The MgAl₂O₄ phase of Mg/Al₂O₃ additive is found capable of trapping vanadium while its MgO of Mg/Al₂O₃ phase can migrate to zeolite particles (the active component of the FCC catalyst) that, in turn, causes a decline in the activity of that catalyst.     

Trapping of random walks on the line

Several features of the trapping of random walks on a one-dimensional lattice are analyzed. The results of this investigation are as follows: (1) The correction term to the known asymptotic form for the survival probability ton steps is O(( ₂n)^–1/3), where =–ln(1–c), andc is the trap concentration. (2) The short time form for the survival probability is found to be exp[–a(c)n ^1/2], wherea(c) is given in Eq. (21). (3) The mean-square displacement of a surviving random walker is found to go liken ^2/3for largen. (4) When the distribution of trap-free regions is changed so that very large regions are much rarer than for ideally random trap placement the asymptotic survival probability changes its dependence onn. One such model is studied.     

Hydrolytically stable, diaminocarboxylic acid-based membranes buffering in the pH range from 6 to 8.5 for isoelectric trapping separations

Diaminocarboxylic acid carrier ampholytes, such as L-histidine, 2,3-diaminopropionic acid, L-ornithine, and L-lysine, were reacted with glycerol-1,3-diglycidyl ether (GDGE) and poly(vinyl alcohol) (PVA) in the presence of sodium hydroxide to produce hydrolytically and mechanically stable hydrogels, supported on a PVA substrate, for use as buffering membranes in isoelectric trapping (IET) separations. The pH values of the DACAPVA membranes were determined with the help of small-molecule pI markers and proteins and were found to be in the 6 < pH < 8.5 range. The membranes were successfully used to isoelectrically trap small ampholytes, desalt ampholyte solutions in IET mode, and effect the binary separation of chicken egg white proteins.     

稳定氮氧自由基TMPO和TMPRO的合成与应用

本文评述了近年来4-氧-2,2,6,6-四甲基哌啶-1-氧自由基(TMPO)和2,2,5,5-四甲基吡咯啉-1-氧自由基(TMPRO)及其衍生物在合成和应用方面的进展,着重讨论了这些氮氧自由基的合成方法和作为自旋标记试剂的应用。     

Capillary gas chromatography of lower aliphatic C2?C5 aldehydes in the free form as a group of pungent odorants in air

The capillary gas chromatography of the C₂-C₅ lower aliphatic aldehydes (e.g.,acetaldehyde, propionaldehyde, n- and i-butyraldehydes, n- and i-valeraldehydes) which, in the free form in air, have unpleasant odors and low threshold odor values, has been studied using cold-trap preconcentration with liquid oxygen. The capillary column outlet was connected to enable simultaneous detection by FID, ECD, FPD AND FTD (SID).     

Multi-purpose functionality for the structural elaboration of the piperazine-2,5-dione motif

Mild methods for controlled C- and N-alkylation of 3-benzyloxycarbonylpiperazine-2,5-diones are reported. The benzyloxylcarbonyl substituent can also serve as latent functionality for N-acyliminium ion formation and subsequent trapping enables installation of new carbon and/or heteroatom substituents.     

Random walks on inhomogeneous lattices

For lattices with two kinds of points (black and white), distributed according to a translation-invariant joint probability distribution, we study statistical properties of the sequence of consecutive colors encountered by a random walker moving through the lattice. The probability distribution for the single steps of the walk is considered to be independent of the colors of the points. Several exact results are presented which are valid in any number of dimensions and for arbitrary probability distributions for the coloring of the points and the steps of the walk. They are used to derive a few general properties of random walks on lattices containing traps.Presented at the Symposium on Random Walks, Gaithersburg, MD, June 1982.     

EPR studies on H-abstraction from methylbenzenes by “magic blue” reagent

After mixing a methylbenzene 4 with “magic blue” solution in F113 (CClF₂CCl₂F) containing bis{perfluoro[1-(2-fluorosulfonyl)ethoxy]ethyl}nitroxide 2 and perfluoro-1-nitroso-1-[1-(2-fluorosulfonyl)ethoxy]ethane 3 at room temperature, benzylic H-atom of 4 could be selectively abstracted by 2, and benzyl radical 5 thus generated was immediately trapped by 3. Based on hyper-fine splitting constants (hfsc), the structure of the spin adducts perfluoro[1-(2-fluorosulfonyl)ethoxy]ethyl benzyl nitroxides 6 derived from seven methylbenzenes have been identified. The mechanism of the H-abstraction/spin trapping process is also discussed.     

Initiation Mechanism of Polymerization of Acryl－amide by Ceric Ion／2－Benzoyl Acetanilide System

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