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1.
Juan Bisceglia María B. García Rosana Massa María L. Magri Mariana Zani Gabriel O. Gutkind Liliana R. Orelli 《Journal of heterocyclic chemistry》2004,41(1):85-90
A method is described for the synthesis of bis(3‐aryl‐1‐hexahydropyrimidinyl)methanes 1, by condensation of N‐aryl‐1,3‐propanediarnines 2 with formaldehyde. The reaction mechanism involves N‐arylhexahydropyrimidines 3 as intermediates. Such compounds can also be prepared efficiently by a methylene exchange reaction between bis‐hexahydropyrimidines 1 and the corresponding diamines 2. The antimicrobial activity of compounds 1 was evaluated by the disk diffusion method and some of them showed moderate to good growth inhibition activity. 相似文献
2.
The rate of quenching of triplet excitions by trapped holes in crystalline pyrene has been measured as a function of hole concentration. The rate constant is γ=4.5×10?11 cm3 sec?1 within 50%, not far below that of a diffusion limited process. The quenching by free holes is not observed in the experimental conditions used. 相似文献
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Isabel A. Perillo María B. García Juan . Bisceglia Liliana R. Orelli 《Journal of heterocyclic chemistry》2002,39(4):655-661
A series of N‐arylhexahydropyrimidines la‐1 were synthesized by condensation of N‐aryl‐N'‐alkyl‐ (or aryl)‐1,3‐propanediamines 2a‐h with aldehydes. Reactions with formaldehyde proceeded in hydroalcoholic solution, while condensation with aromatic aldehydes required in general the use of activated molecular sieves. 1H NMR spectra of compounds la‐1 were analyzed and the results correlated with their conforma‐tional features. Derivatives devoid of a 2‐substituent la‐g show fast ring reversal and N‐inversion. The presence of a 2‐aryl group shifts the ring reversal equilibrium towards conformations where the 2‐aryl substituent is equatorial. Differential assignment of axial and equatorial hydrogens in these compounds was made on the basis of coupling constants and chemical shift values. In compound 1k spectral data suggest the axial orientation of the N‐methyl group. Such findings were confirmed in the corresponding NOESY spectrum. 相似文献
5.
We report a sample pretreatment approach for the analysis of total cocaine residues in wastewater that eliminates the need
for two key assumptions often made in estimating cocaine utilization from measurement of its benzoylecgonine metabolite: that
benzoylecgonine is neither degraded nor generated during transport in a sewer system, and that it is excreted as a constant
fraction of cocaine ingested. By adding NaOH and incubating samples at 55 °C, cocaine and its principal metabolites are efficiently
hydrolyzed into ecgonine, anhydroecgonine, and norecgonine. Ecgonine, estimated to represent between 37% and 90% (on a molar
basis) of cocaine residues, can be directly determined (without preconcentration via solid-phase extraction (SPE)) by reversed-phase
(RP) or hydrophilic interaction liquid chromatography–tandem mass spectrometry (LC/MS/MS). If samples are subjected to SPE,
anhydroecgonine can also be determined; this metabolite (and its precursors) represents ≈7% of urinary cocaine residues (based
on spot collections from living individuals). Although a reference standard for norecgonine is not commercially available,
such nortropanes are also a minor fraction (up to 2%) of urinary cocaine residues. The stability of two human markers (cotinine
and creatinine) to the hydrolysis procedure was also investigated. Results obtained by applying the hydrolysis approach for
the analysis of total cocaine in an untreated municipal wastewater sample (obtained from Baltimore, MD) were generally in
excellent agreement with those obtained from split samples analyzed using a more comprehensive solid-phase extraction RPLC/MS/MS
method as described in our previous work. In particular, total tropane-based cocaine residues were found to be hydrolyzed
to ecgonine with 98–99% efficiency. 相似文献
6.
Kevin J. Bisceglia Jim T. Yu Mehmet Coelhan Edward J. Bouwer A. Lynn Roberts 《Journal of chromatography. A》2010,1217(4):558-564
The presence of pharmaceuticals and other wastewater-derived micropollutants in surface and groundwaters is receiving intense public and scientific attention. Yet simple GC/MS methods that would enable measurement of a wide range of such compounds are scarce. This paper describes a GC/MS method for the simultaneous determination of 13 pharmaceuticals (acetaminophen, albuterol, allopurinol, amitriptyline, brompheniramine, carbamazepine, carisoprodol, ciclopirox, diazepam, fenofibrate, metoprolol, primidone, and terbinafine) and 5 wastewater-derived contaminants (caffeine, diethyltoluamide, n-butylbenzene sulfonamide, n-nonylphenol, and n-octylphenol) by solid phase extraction (SPE) and derivatization with BSTFA. The method was applied to the analysis of raw and treated sewage samples obtained from a wastewater treatment plant located in the mid-Atlantic United States. All analytes were detected in untreated sewage, and 14 of the 18 analytes were detected in treated sewage. 相似文献
7.
Capillary electrophoresis analysis of different variants of the amyloidogenic protein β2‐microglobulin as a simple tool for misfolding and stability studies 下载免费PDF全文
Laura Bertoletti Federica Bisceglia Raffaella Colombo Sofia Giorgetti Sara Raimondi P. Patrizia Mangione Ersilia De Lorenzi 《Electrophoresis》2015,36(19):2465-2472
Free solution capillary electrophoresis with UV detection is here used to retrieve information on the conformational changes of wild‐type β2‐microglobulin and a series of naturally and artificially created variants known to have different stability and amyloidogenic potential. Under nondenaturing conditions, the resolution of at least two folding conformers at equilibrium is obtained and a third species is detected for the less stable isoforms. Partial denaturation by using chaotropic agents such as acetonitrile or trifluoroethanol reveals that the separated peaks are at equilibrium, as the presence of less structured species is either enhanced or induced at the expenses of the native form. Reproducible CE data allow to obtain an interesting semiquantitative correlation between the peak areas observed and the protein stability. Thermal unfolding over the range 25–42°C is induced inside the capillary for the two pathogenic proteins (wtβ2‐microglobulin and D76N variant): the large differences observed upon small temperature variation draw attention on the robustness of analytical methods when dealing with proteins prone to misfolding and aggregation. 相似文献
8.
Jimena E. DíazJuan Á. Bisceglia Ma. Cruz MolloLiliana R. Orelli 《Tetrahedron letters》2011,52(16):1895-1897
In the present Letter we report the use of N-arylputrescines as synthetic intermediates for the preparation of N-acyl-N′-aryltetramethylenediamines 3 and related seven-membered heterocyclic amidines 4. Compounds 1 were synthesized by Cs2CO3/KI-mediated aminolysis of 4-chlorobutyronitrile and subsequent reduction. N-Acylation of diamines 1 with carboxylic acid anhydrides led selectively to N-acyl-N′-aryl tetramethylenediamines 3. Microwave-assisted ring closure of such precursors promoted by PPE allowed for the synthesis of hitherto unreported 1-aryl-2-alkyl-1H-1,4,5,6-tetrahydro-1,3-diazepines 4. 相似文献
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Kevin J. Bisceglia A. Lynn Roberts Michele M. Schantz Katrice A. Lippa 《Analytical and bioanalytical chemistry》2010,398(6):2701-2712
We present an isotopic-dilution direct injection reversed-phase liquid chromatography–tandem mass spectrometry method for
the simultaneous determination of 23 drugs of abuse, drug metabolites, and human-use markers in municipal wastewater. The
method places particular emphasis on cocaine; it includes 11 of its metabolites to facilitate assessment of routes of administration
and to enhance the accuracy of estimates of cocaine consumption. Four opioids (6-acetylmorphine, morphine, hydrocodone, and
oxycodone) are also included, along with five phenylamine drugs (amphetamine, methamphetamine, 3,4-methylenedioxy-methamphetamine,
methylbenzodioxolyl-butanamine, and 3,4-methylenedioxy-N-ethylamphetamine) and two human-use markers (cotinine and creatinine). The method is sufficiently sensitive to directly quantify
(without preconcentration) 18 analytes in wastewater at concentrations less than 50 ng/L. We also present a modified version
of this method that incorporates solid-phase extraction to further enhance sensitivity. The method includes a confirmatory
LC separation (selected by evaluating 13 unique chromatographic phases) that has been evaluated using National Institute of
Standards and Technology Standard Reference Material 1511 Multi-Drugs of Abuse in Freeze-Dried Urine. Seven analytes (ecgonine
methyl ester, ecgonine ethyl ester, anhydroecgonine methyl ester, m-hydroxybenzoylecgonine, p-hydroxybenzoyl-ecgonine, ecgonine, and anhydroecgonine) were detected for the first time in a wastewater sample. 相似文献