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11.
The mass spectra of two series of aliphatic polynitro compounds are reported and discussed. The fragmentation patterns of aliphatic nitro and polynitro compounds are similar in that no appreciable molecular ion current is observed; however, there are several other features in the fragmentation of aliphatic polynitro compounds which differ from that of nitroalkane spectra. Both series of compounds studied-C(NO2)x(CH3)4?x, where x = 4 to 0 and C2(NO2)x(CH3)6?x, where x = 6,4,2-show a decrease in the number and intensity of alkylions with an increase in the NO+ and NO2+ ion current as x increases. The main ions resulting from the more nitrated compounds are [NO]+, [NO2]+, [CO2]+. and [CH3CO]+, whose noncharged counterparts are the principal species produced in the detonation of these compounds. This similarity of the products of the two processes suggests the use of mass spectroscopy for the investigation of the initial explosive processes. The principal fragmentation pathways of the polynitroalkanes have been elucidated by exact mass measurements and the observation of metastable ion transitions. 相似文献
12.
Kent Morrill Robert E. Linder Edith M. Bruckmann Günter Barth Edward Bunnenberg Carl Djerassi Lloyd Seamans Albert Moscowitz 《Tetrahedron》1977,33(8):907-911
The magnetic CD spectra of a number of Me substituted trans-2-decalones and bicyelo[2.2.2]octan-2-ones were measured. The results showed a large, and sometimes dominant, contribution to the MCD intensity which could be correlated with the presence of α-substituents lying outside of the plane of the carbonyl chromophore. 相似文献
13.
Abdou O. Abdelhamid Cyril Prknyi S. M. Khaledur Rashid Winston D. Lloyd 《Journal of heterocyclic chemistry》1988,25(2):403-405
Substituted 2-arylbenzimidazoles, 2-arylbenzoxazoles and 2-arylbenzothiazoles were obtained in good yield by the reaction of hydroximoyl chlorides with ortho-substituted aromatic amines. The benzo moiety of the benzimidazoles was shown by nmr to be symmetrical, indicating that the N-H group proton of the imidazole ring is exchanging with the water protons in the DMSO-d6 solvent. 相似文献
14.
Structure Elucidator: a versatile expert system for molecular structure elucidation from 1D and 2D NMR data and molecular fragments 总被引:2,自引:0,他引:2
Elyashberg ME Blinov KA Williams AJ Molodtsov SG Martin GE Martirosian ER 《Journal of chemical information and computer sciences》2004,44(3):771-792
StrucEluc is an expert system that allows the computer-assisted elucidation of chemical structures based on the inputs of a series of spectral data including 1D and 2D NMR and mass spectra. The system has been enabled to allow a chemist to utilize fragments stored in a fragment database as well as user-defined fragments submitted by the chemist in the structure elucidation process. The association of fragments in this way has been shown to dramatically speed up the process of structure generation from 2D NMR data and has helped to minimize or eliminate the need for user intervention thereby further enabling the vision of automated elucidation. The use of fragments has frequently transformed very difficult 2D NMR elucidation challenges into easily solvable tasks. A strategy to utilize molecular fragments has been developed and optimized based on specific challenging examples. This strategy will be described here using real world examples. Experience gained by solving more than 150 structure elucidation problems from a variety of literature sources is also reviewed in this work. 相似文献
15.
16.
A number of 6(5H)-phenanthridinones have been conveniently prepared from 9-oxofluorenes through the Schmidt reaction. It has been found that all amino and nitro 9-oxofluorenes thus far tried gave substituted 6(5H)-phenanthridinones with the amino or nitro group situated in the benzene ring attached to the nitrogen of the lactam group. UV and IR spectral data are presented for these compounds. 相似文献
17.
Kuntebommanahalli N. Thimmaiah Winston D. Lloyd Gujjarahalli T. Chandrappa 《Transition Metal Chemistry》1985,10(3):94-96
Summary Complexes of vanillinsemicarbazone (VSC) with MnII, FeII, CoII, NiII, CuII, ZnII, CdII and HgII have been prepared and characterised by elemental analyses, molar conductance, magnetic susceptibility and spectral data.
Probable structures for the complexes are suggested on the basis of their physico-chemical properties. The fungitoxicity of
VSC and the isolated complexes have been tested on pathogenic fungi.
On leave from the University of Mysore, India. 相似文献
18.
R. E. Lloyd R. A. Larson Tracy L. Adair R. W. Tuveson 《Photochemistry and photobiology》1993,57(S1):1011-1017
Abstract— Copper(II), in the presence of UV-B radiation(280–315 nm), can generate single-strand breaks in the sugar-phosphate backbone of pBR322 plasmid DNA. A low level of single-strand backbone breaks occurs in the presence of Cu(II) alone, but UV-B irradiation increases the rate by the more than 100-fold. Concomitant with the damage to the DNA backbone is a loss of transforming activity. Oxygen is required for generation of the single-strand breaks but not for the loss of transforming activity. A DNA glycosylase (Fpg), which participates in the repair of certain DNA nitrogenous base damage, does not repair plasmid DNA damaged by Cu(II). The hydroxyl radical scavenging compound DMSO is only somewhat effective at protecting the physical and biological properties of the DNA. These results with Cu(II) are compared to those obtained previously with pBR322 plasmid DNA in the presence of Fe(III) and UV-A. 相似文献
19.
Lloyd J. Guggenberger 《Journal of organometallic chemistry》1974,81(2):271-280
The crystal structure of tris(triphenylphosphine)gold(I)[dodecahydrido-6-thia-nido-decaborate(1—)], [(C6H5)3P]3AuB9H12S, has been determined using X-ray techniques and counter data. The compound is a salt consisting of [(C6H5)3P]3Au+ cations and B9H12S? anions. The cation is trigonal and nearly planar with AuP distances of 2.382(5) Å and PAuP anglés of 119.3(36)°. The B9H12S? thiaborane anion is an open icosahedral fragment with the S atom in the 6 position, on the periphery of the decaborane polyhedron. The structure is the same as that found in solution for the isoelectronic B10H142? anion. Crystals are triclinic, space group P, with a = 13.086(12), b = 19.635(32), c = 11.180(8) Å, α = 103.60(16), β = 72.10(9), and γ = 94.76(15)°. The structure was refined by least squares to a conventional R of 0.077. 相似文献
20.
While there is a considerable interest in the food industry in determining various analytes using ion-selective electrodes (ISEs), only few reports describe their use for direct measurements in food. In this study, the suitability of glass electrodes and ionophore-based solvent polymeric ISEs for the determination of pH in Process cheese, Cheddar cheese and milk was investigated. The liquid junction potential between a 3 M KCl bridge electrolyte and diluted as well as undiluted Process cheese was found to be negligible. Reference electrodes with ceramic plug and sleeve-type junctions performed well, although precautions needed to be taken to prevent plugging at the junctions. While the protein rennet casein posed no problems in pH measurements, the extraction of neutral lipophilic compounds or hydrophobic peptides into solvent polymeric membranes was evident, resulting in some loss of selectivity for monovalent cations upon exposure to cheese. However, it was found that ISEs based on tridodecylamine (R3N) as ionophore and o-nitrophenyl octyl ether (oNPOE) as plasticizer can be used to accurately measure the pH of milk and, after desensitization of the electrodes in a cheese emulsion, of diluted Process cheese. Since pH measurements with a glass electrode showed that emulsions of cheese moderately diluted to a cheese content of 70% have the same pH as undiluted cheeses, it is possible to determine the pH in cheese with ionophore-based ISEs. R3N membranes also performed well in undiluted milk. 相似文献