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131.
Leslie M. Werbel Dennis J. Mcnamara Norman L. Colbry Judith L. Johnson Margaret J. Degnan Barbara Whitney 《Journal of heterocyclic chemistry》1979,16(5):881-894
The synthesis of a series of N,N-dialkyl-6-(substituted phenyl)-1,2,4,5-tetrazin-3-amines (IV) by two routes is described. The first route (Scheme I) involved the oxidative cyclization of formazans (II) to 3-bromo-6-(substituted phenyl)-1,2,4,5-tetrazines (III), followed by treatment with amines. The second (Scheme II) utilized the treatment of 3-(methylthio)-6-(substituted phenyl)-1,2,4,5-tetrazines (VII) with amines to provide the desired products. The intermediate 3-(methylthio)-6-(substituted phenyl)-1,2,4,5-tetrazines (VII) were obtained by thiobenzoylation of hydrazinecarbohydrazonothioic acid methyl ester with [[(substituted phenyl)thioxomethyl]thio]-acetic acids (V) to afford the 1,2-dihydro-3-(methylthio)-6-(substituted phenyl)-1,2,4,5-tetrazines (VI). Oxidation with bromine in acetic acid provided the desired intermediates. The target 6-(substituted phenyl)-1,2,4,5-tetrazin-3-amines (IV) displayed modest antimalarial activity. 相似文献
132.
Haiwen Zhang David W. Norman Tracey M. Wentzell Alison M. Irving Janet P. Edwards Susan L. Wheaton Christopher M. Vogels Stephen A. Westcott Felix J. Baerlocher Andreas Decken 《Transition Metal Chemistry》2005,30(1):63-68
Reactions of salicylaldehydes with boronate ester derivatives of aniline have been examined. Addition of these Schiff base ligands to palladium acetate or Na2PdCl4 afforded novel boron-containing trans-bis(N-arylsalicylaldiminato) palladium complexes.Condensation of salicylaldehyde (2-HOC6H4C(O)H) with H2NC6H4Bpin (pin=1,2-O2C2Me4) afforded the boron-containing Schiff bases, 2-HOC6H4C(H)=NC6H4Bpin (1–3a). Similar reactivity with 2-hydroxy-5-nitrobenzaldehyde and 2-hydroxy-1-naphthaldehyde gave the corresponding Schiff bases (1-3b) and (1-3c), respectively. Reaction of Schiff bases (2) and (3) with palladium acetate or Na2PdCl4 afforded complexes of the type PdL2
(4,5), where L=deprotonated Schiff base. The molecular structure of the nitro-salicylaldehyde 4-Bpin palladium complex (5b) was characterized by an X-ray diffraction study. All new palladium compounds have been characterized fully and tested for their antifungal activity against Aspergillus niger and Aspergillus flavus. 相似文献
133.
本文回顾了在羰基引发剂的作用下烯烃单体光引发聚合的最新机理。报道了有关多种当前通用的新型羰基引发剂的光物理和光化学的近期工作,其中包括 UV 吸收,发光光谱和闪光光解的研究。还报道了油溶性引发剂对丙烯酸丁酯的光聚合效应。证明油溶性引发剂实质上是经过三重态来起作用,其中包含一个从溶剂中攫取氢的引发步骤。对于硫杂蒽酮衍生物来说,它们从叔胺接受电子的能力及其光聚合效应之间有一定的关系。从闪光光解获得的证据说明在这种情况下存在着自由基阴离子,但是基于二苯酮和苯基酮的引发剂则没有。预料后者直接从胺攫氢是通过三重态羰基或是引发剂的自由基。有证据表明联苯甲酰主要是通过光裂解来起作用。水溶性硫杂蒽酮引发剂的作用主要是经过单重态,其中包含引发时攫氢一步。在这种情况下,自由基的形成不受氧的影响。 相似文献
134.
Cycloheptyne-dicobalt hexacarbonyl complexes, substituted by propargylic ether functions, undergo 2 + 2 + 2 cycloaddition reactions with alkynes to give tricyclic benzocycloheptanes; an all-intramolecular version of this transformation is also possible. 相似文献
135.
Terence C. Gibb Robert Greatrex Norman N. Greenwood Kenneth G. Snowdon 《Journal of solid state chemistry》1975,14(2):193-202
The magnetic and structural properties of the solid solution SrFexRu1?xO3?y (0 ? x ? 0.5) have been studied using 57Fe and 99Ru Mössbauer spectroscopy and other techniques. These phases, which are here reported for the first time, have a distorted perovskite structure. The iron substitutes exclusively as Fe3+ and thereby causes oxygen deficiency, but has little effect on the magnetic behaviour of the Ru4+ until x > 0.2, whereupon the metallic band system begins to revert to a localized electron structure. The properties of a sample with x = 0.3 are complex and intermediate in character. For x > 0.3 the oxygen deficiency is reduced by substantial oxidation to Ru5+ until at x = 0.5 the system corresponds to Sr2Fe3+Ru5+O6. 相似文献
136.
137.
Norman G. Anderson 《Fresenius' Journal of Analytical Chemistry》1972,261(4-5):257-271
Summary New instrumentation has been developed at ORNL for analyzing physiologic specimens. The system is designed for use in clinical laboratories, hospitals, and emergency rooms and for use by researchers. Miniaturized versions may also be used in prolonged space flights.After consideration of ease of automation, flexibility, and rapid startup, multiple analyses performed in parallel was chosen as the desired approach. Concepts employed in developing the system are discussed, including:(1) dynamic mixing of samples and reagents through centrifugal transfer from transfer disks into cuvets; (2) rotor design allowing emptying, flushing, and drying of cuvets; (3) precise temperature control; (4) spectrophotometric reaction monitoring; (5) data reduction, with all data stored for possible recall; (6) feedback control for error correction and time saving. Possible future improvements are indicated.
Entwicklung schneller Analysatoren
Zusammenfassung Im Oak Ridge National Laboratory wurde ein neues Analysatorsystem entwickelt, das für die Analyse physiologischer Proben bestimmt ist und in klinischen Laboratorien, Krankenhäusern, Unfallstationen, Forschungsinstituten sowie in einer verkleinerten Version auch in der Raumfahrt zum Einsatz gelangen kann.Das System zeichnet sich aus durch leichte Automatisierbarkeit, Flexibilität, rasche Inbetriebnahme und eignet sich für parallel durchgeführte Serienanalysen. Die folgenden Charakteristica des Systems werden diskutiert: 1. Dynamisches Mischen von Proben und Reagentien durch zentrifugale Übertragung in die Küvetten, 2. Entleeren, Spülen und Trocknen der Küvetten durch Rotation, 3. Genaue Temperaturkontrolle, 4. Spektrophotometrische Reaktionsüberwachung, 5. Datenberechnung mit Speicherung aller Werte für möglichen Abruf, 6. Feedback-Kontrolle zur Fehlerkorrektur und Zeiteinsparung. Mögliche zukünftige Verbesserungen werden erwähnt.
Operated for the U.S. Atomic Energy Commission by the Nuclear Division of Union Carbide Corporation. 相似文献
138.
The substrate specificity of 4-oxalocrotonate tautomerase (4-OT) is characterized by electrostatic interactions between positively charged arginine (Arg) side chains on the enzyme and the dianionic substrate, 4-oxalocrotonate. To generate specific hydrogen-bonding interactions with a monoanionic substrate analogue, we have introduced a urea functional group into the active site by replacing arginine side chains with isosteric citrulline (Cit) residues. This design was based on the complementarity between the urea functionality of citrulline and the uncharged amide function of the substrate, as opposed to the guanidinium-carboxylate electrostatic interaction between the wild-type enzyme and the natural substrate. Indeed, the synthetic (Arg39Cit)4-OT analogue catalyzed the tautomerization of the non-natural monoamide-monoacid substrate while it was a poor catalyst for the natural diacid substrate. The specificity of (Arg39Cit)4-OT for the monoamide-monoacid substrate relative to that of the diacid substrate was found to be 740-fold greater than that of the wild-type enzyme for tautomerization of the non-natural substrate as compared with the natural one. The role of electrostatic interactions in the tautomerization of the monoamide-monoacid substrate was probed in detail with several other Arg to Cit analogues of this enzyme. This study has demonstrated that chemical manipulation of the functional groups within the active site of an enzyme can modify its catalytic activity and substrate specificity in a predictable way, suggesting that the incorporation of noncoded amino acids into proteins has great promise for the development of new enzymatic mechanisms and new binding interactions. 相似文献
139.
Alan H. Cowley Andreas Decken Claudia A. Olazbal Nicholas C. Norman 《无机化学与普通化学杂志》1995,621(11):1844-1848
Further investigation of the reaction of Ar*GaCl2 (Ar* = 2,4,6-t-Bu3C6H2) with Na[Mn(CO)5] resulted in the new compound, [Ga(Ar*){Mn(CO)5}2] 2 . The new indium compounds, [In(Ar*){Co(CO)4}2] 3 and [In(Ar*){Mn(CO)5}2] 4 , have been prepared by the treatment of Ar*InBr2 with Na[Co(CO)4] and Na[Mn(CO)5], respectively. The structure of 3 was established by single-crystal X-ray diffraction: space group P1 (No. 2), Z = 2, a = 8.625(1) Å, b = 10.557(2) Å, c = 17.55(2) Å, α = 88.43(1)°, β = 83.45(1)°, γ = 71.14(1)°. The X-ray crystal structure of [Ga{Mn(CO)5}3] is also reported: space group Pbca (No. 61), Z = 8, a = 12.83(3) Å, b = 11.753(2) Å, c = 29.662(6) Å, α = β = γ = 90°. 相似文献
140.
The GC–MS characteristics of trifluoroacetate esters of phenolic compounds are discussed. Linear temperature programmed retention indices and total ion current MS response factors of over 120 phenolic esters are reported. The main GC advantages from analysis of trifluoroacetate esters as compared to plain phenols are enhanced volatility and improved resolution. For example, the elution temperature of a given phenol is typically 50 °C greater than that of the corresponding trifluoroacetate ester. Also, while retention of compounds with two trifluoroacetate groups is only moderately greater than mono esters, underivatized dihydroxy compounds are very difficult to elute from any GC column. Complete resolution of isomeric C0-, C1- and C2-alkylphenol esters is readily achieved on conventional fused silica GC columns; resolution of the corresponding underivatized compounds requires specialized GC columns with low temperature limits. In general, mass spectra of trifluoroacetate esters are more characteristic of a given structure than those of the corresponding phenols and may be more rigorously interpreted towards structural elucidation. A table in the report summarizes some of the more important spectral features used in compound identification. Example applications in analysis of coal-, shale- and petroleum-derived materials are presented. Selected ion monitoring is used to determine individual phenolic components in whole distillates; reconstructed ion chromatograms are used to illustrate distributions of selected species as a function of fuel storage and thermal stress. 相似文献