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91.
Suresh P S Ravi Kumar Trivedi Nuggehally R. Srinivas Ramesh Mullangi 《Biomedical chromatography : BMC》2020,34(1):e4742
Quantitation of drugs used for the treatment of chronic lymphocytic leukemia in various biological matrices during both pre-clinical and clinical developments is very important, often in routine therapeutic drug monitoring. The first developed methods for quantitation were traditionally done on LC in combination with either UV or fluorescence detection. However, the emergence of LC with mass spectrometry in tandem in early 1990s has revolutionized the quantitation as it has provided better sensitivity and selectivity within a shorter run time; therefore it has become the choice of method for the analysis of various drugs. In this article, an overview of various bioanalytical methods (HPLC or LC–MS/MS) for the quantification of drugs for the treatment of chronic lymphocytic leukemia, along with applicability of these methods, is given. 相似文献
92.
A detailed chemical kinetic model has been developed for supercritical water oxidation (SCWO) of methylamine, CH3NH2, providing insight into the intermediates and final products formed in this process as well as the dominant reaction pathways. The model was adapted from previous mechanisms, with a revision of the peroxyl radical chemistry to include imine formation, which has recently been identified as the dominant gas-phase pathway in amine oxidation. The developed model can reproduce previous experimental data on methylamine consumption and major product formation to reasonable accuracy, although with deficiencies in describing the induction time. Our simulations indicate that oxidation of the •CH2NH2 radical to methanimine, CH2NH, is the major channel in methylamine SCWO, with subsequent hydrolysis of CH2NH providing the experimentally observed reaction products ammonia and formaldehyde. Integral-averaged reaction rates were used to identify major reaction pathways, and a first-order sensitivity analysis indicated that the concentration of CH3NH2 is most sensitive to OH radical kinetics. Overall, this work clarifies the importance of imine chemistry in the oxidation of nitrogen-containing compounds and indicates that they are necessary to model these compounds in SCWO processes. 相似文献
93.
Cyclopentane and methylcyclopentane oxidation was investigated in a jet-stirred reactor at atmospheric pressure, over temperatures ranging from 900 to 1250 K, for fuel-lean, stoichiometric, and fuel-rich mixtures at a constant residence time of 70 ms. The initial mole fraction of both fuels was kept constant at 1000 ppm. The reactants were highly diluted by a flow of nitrogen to ensure thermal homogeneity. Samples of the reacting mixture were analyzed online and off-line by Fourier transform infrared spectroscopy and gas chromatography. A detailed kinetic mechanism consisting of 590 species involved in 3469 reactions was developed, and simulation results were compared to these new experimental data and previously reported ignition delays. Reaction pathways analysis as well as sensitivity analyses were performed to get insights into the differences observed during the oxidation process of cyclopentane and methylcyclopentane. 相似文献
94.
Olivier Herbinet Benoit Husson Hervé Le Gall Frédérique Battin-Leclerc 《国际化学动力学杂志》2020,52(12):1006-1021
In the context of better understanding pollutant formation from internal combustion engines, new experimental speciation data were obtained in a high-pressure jet-stirred reactor for the oxidation of three molecules, which are considered in surrogates of diesel fuel, n-heptane, ethylbenzene, and n-butylbenzene. These experiments were performed at pressures up to 10 bar, at temperatures ranging from 500 to 1 100 K, and for a residence time of 2 s. Based on results previously obtained close to the atmospheric pressure for the same molecules, the pressure effect on fuel conversion and product selectivity was discussed. In addition, for the three fuels, the experimental temperature dependence of species mole fractions was compared with simulations using recent literature models with generally a good agreement. For n-heptane, the obtained experimental data, at 10 bar for stoichiometric mixtures, included the temperature dependence of the mole fractions of the reactants and those of 21 products. Interestingly, the formation of species previously identified as C7 diones was found significantly enhanced at 10 bar compared with lower pressures. The oxidation of ethyl- and n-butylbenzenes was investigated at 10 bar for equivalence ratios of 0.5, 1, and 2. The obtained experimental data included the temperature dependence of the mole fractions of the reactants and those of 13 products for the C8 fuels and of 19 products for the C10 one. For ethylbenzene under stoichiometric conditions, the pressure dependence (from 1 to 10 bar) of species mole fraction was also recorded and compared with simulations with more deviations obtained than for temperature dependence. For both aromatic reactants, a flow rate analysis was used to discuss the main pressure influence on product selectivities. 相似文献
95.
Yuto Kurasaki Yasuhito Suzuki Akikazu Matsumoto 《Journal of polymer science. Part A, Polymer chemistry》2020,58(7):923-931
We carried out the thermal curing of the copolymers of N-allylmaleimide (AMI) and 2-ethylhexyl acrylate (2EHA) using 1,3,4,6-tetra(2-mercaproethyl)glycoluril ( G1 ), 1,3,4,6-tetra(3-mercaptopropyl)glycoluril ( G2 ), 1,3,4,6-tetraallylglycoluril ( G3 ), triallylisocyanurate (TAIC), and pentaerythritol tetrakis(3-mercaptobutyrate) (PEMB) as the crosslinkers. Based on the results for the analysis of thiol–ene reactions monitored by IR spectroscopy, it was confirmed that the curing rate significantly depended on the combination of the used crosslinkers. The insoluble fraction after curing was more than 90% for the systems using the glycoluril crosslinkers, while the conversion of the allyl groups was suppressed due to the rigid structure of these crosslinkers. The heat resistance and the mechanical properties of the crosslinked polymers were investigated by thermogravimetric analysis, differential scanning calorimetry, dynamic mechanical analysis, and mechanical tensile tests. For the products cured using the glycoluril crosslinkers, the glass transition temperature (Tg) and the maximum temperature of thermal decomposition (Tmax) were 54–59 °C and 395–409 °C, respectively, being higher than those for the cured product prepared with PEMB and TAIC as the conventional crosslinkers. The elasticity (75–139 MPa), the maximum strength (3.0–4.1 MPa), and the adhesion strength (6.7–10.7 MPa) for the polymers cured with the glycoluril crosslinkers, determined by the mechanical tensile and single lap-shear adhesion tests, were higher than those for cured materials produced with PEMB. Thus, the thermal and mechanical properties of the maleimide copolymers were efficiently enhanced by crosslinking using the rigid glycoluril compounds. © 2020 Wiley Periodicals, Inc. J. Polym. Sci. 2020 , 58, 923–931 相似文献
96.
Yu-Yi Zhang De-Shan Zhang Tian Li Dr. Mohamedally Kurmoo Prof. Dr. Ming-Hua Zeng 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(3):721-728
Dehydration of (S,S)-1,2-bis(1H-benzo[d]imidazol-2-yl)ethane-1,2-diol (H4L) to (Z)-1,2-bis(1H-benzo[d]imidazol-2-yl)ethenol) (H3L′) was found to be metal-assisted, occurs under solvothermal conditions (H2O/CH3OH), and leads to [MnII4(H3L)4Cl2]Cl2 ⋅ 5 H2O ⋅ 5 CH3OH ( Mn4L4 ) and [MnII4(H2L′)6(μ3-OH)]Cl ⋅ 4 CH3OH ⋅ H2O ( Mn4L′6 ), respectively. Their structures were determined by single-crystal XRD. Extensive ESI-MS studies on solutions and solids of the reaction led to the proposal consisting of an initial stepwise assembly of Mn4L4 from the reactants via [MnL] and [Mn2L2] below 80 °C, and then disassembly to [MnL] and [MnL2] followed by ligand modification before reassembly to Mn4L′6 via [MnL′], [MnL′2], and [Mn2L′3] with increasing solvothermal temperature up to 140 °C. Identification of intermediates [Mn4LxL′6−x] (x=5, 4, 3, 2, 1) in the process further suggested an assembly/disassembly/in situ reaction/reassembly transformation mechanism. These results not only reveal that multiple phase transformations are possible even though they were not realized in the crystalline state, but also help to better understand the complex transformation process between coordination clusters during “black-box” reactions. 相似文献
97.
Shuping Zhang Dr. Hongpan Rong Tianyi Yang Bing Bai Prof. Jiatao Zhang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(18):4025-4031
Dilute alloy nanostructures have been demonstrated to possess distinct catalytic properties. Noble-metal-induced reduction is one effective synthesis strategy to construct dilute alloys and modify the catalytic performance of the host metal. Herein, we report the synthesis of ultrafine PtRu dilute alloy nanodendrites (PtRu NDs, molar ratio Ru/Pt is 1:199) by the reduction of RuIII ions induced by Pt metal. For the methanol oxidation reaction, PtRu NDs showed the highest forward peak current density (2.66 mA cm−2, 1.14 A/mgPt) and the best stability compared to those of pure-Pt nanodendrites (pure-Pt NDs), commercial PtRu/C and commercial Pt/C catalysts. 相似文献
98.
Yingjun Sun Dr. Yingjie Li Yingnan Qin Prof. Lei Wang Prof. Shaojun Guo 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(18):4032-4038
Searching for new anti-poisoning Pt-based catalysts with enhanced activity for alcohol oxidation is the key in direct alcohol fuel cells (DAFCs). However, in the traditional strategy for designing bimetallic or multimetallic alloy is still difficult to achieve a satisfactory heterogeneous electrocatalyst because the activity often depends on only the surface atoms. Herein, we fabricate the multicomponent active sites by creating a sulfide structure on 1D PtNiCo trimetallic nanowires (NWs), to give a PtNiCo/NiCoS interface NWs (IFNWs). Owing to the presence of sulfide interfaces, the PtNiCo/NiCoS IFNWs enable an impressive methanol/ethanol oxidation reaction (MOR/EOR) performance and excellent anti-CO poisoning tolerance. They have the MOR and EOR mass activities of 2.25 Amg-1Pt and 1.62 Amg-1Pt, around 1.26, 3.21 and 1.46, 2.96 times higher than those of PtNiCo NWs and commercial Pt/C, respectively. CO-stripping and XPS measurements further demonstrate that the new interfacial structure and optimal bonding of Pt−CO can result in accelerating the removal of surface adsorbed carbonaceous intermediates. Moreover, such a unique structure has also demonstrated a much-improved ability for the electrochemical detection of some important molecules (H2O2 and NH2NH2). 相似文献
99.
Prof. Dr. Jevgenij A. Raskatov Dr. Scott Virgil Dr. Hsiau-Wei Lee Dr. Lawrence M. Henling Ka Chan Ariel J. Kuhn Alejandro R. Foley 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(20):4467-4470
Methionine (Met) oxidation is an important biological redox node, with hundreds if not thousands of protein targets. The process yields methionine oxide (MetO). It renders the sulfur chiral, producing two distinct, diastereomerically related products. Despite the biological significance of Met oxidation, a reliable protocol to separate the resultant MetO diastereomers is currently lacking. This hampers our ability to make peptides and proteins that contain stereochemically defined MetO to then study their structural and functional properties. We have developed a facile method that uses supercritical CO2 chromatography and allows obtaining both diastereomers in purities exceeding 99 %. 1H NMR spectra were correlated with X-ray structural information. The stereochemical interconversion barrier at sulfur was calculated as 45.2 kcal mol−1, highlighting the remarkable stereochemical stability of MetO sulfur chirality. Our protocol should open the road to synthesis and study of a wide variety of stereochemically defined MetO-containing proteins and peptides. 相似文献
100.
Delfino Chamorro-Arenas Alejandro A. Nolasco-Hernández Dr. Lilia Fuentes Dr. Leticia Quintero Prof. Dr. Fernando Sartillo-Piscil 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(21):4671-4676
Remote and multiple functionalization of piperidines without the use of transition-metal catalysts and elaborate directing groups is one of the major challenges in organic synthesis. Herein is reported an unprecedented two-step protocol that enables the multiple functionalization of piperidines to either 4-substituted or trans-3,4-disubstituted 2-piperidones. First, by exploiting the duality of TEMPO reactivity, which under oxidative and thermal conditions fluctuates between cationic and persistent-radical form, a novel multiple C(sp3)-H oxidation of piperidines to α,β-unsaturated 2-piperidones was developed. Second, the intrinsic low reactivity of the unsaturated piperidones toward conjugated Grignard additions was overcome by using trimethylsilyl chloride (TMSCl) as Lewis acid. Subsequently, conjugated Grignard addition/electrophilic trapping protocol provided substituted 2-piperidone intermediates, some of which were then transformed into pharmaceutical alkaloids. 相似文献