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991.
Zirconium borohydride, a potential reducing agent, reduces acids, esters, imines to the corresponding alcohols and secondary amines in good yield at room temperature within two hours. This facile reducing property was taken advantage off in the synthesis of pheromones and some novel chiral precursors for asymmetric synthesis. 相似文献
992.
A facile, efficient oxidative deblocking of aldoximes and ketoximes to their corresponding aldehydes and ketones have been achieved by using silica gel supported chromium trioxide. 相似文献
993.
D. Bhaskar Reddy P. V. Ramana Reddy M. Muralidhar Reddy M. V. Ramana Reddy S. Vijayalakshmi 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1):325-329
Abstract Some new 1,1,2-trisubstituted ethylenic sulfones have been prepared by the condensation of aryl- and benzylsulfonylmethylsulfonylacetic acid esters with araldehydes. 相似文献
994.
AgOTf proved to be an effective catalyst for the transesterification of β‐keto esters with primary, secondary and tertiary alcohols. The products were obtained in high yield within a reasonable reaction time period. The kinetics of the transesterification reaction were also studied and the reaction was found to follow second‐order kinetics. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
995.
The N-terminal amino acids of proteins are important structure units for maintaining the biological function, localization, and interaction networks of proteins. Under different biological conditions, one or several N-terminal amino acids could be cleaved from an intact protein due to processes, such as proteolysis, resulting in the change of protein properties. Thus, the ability to quantify the N-terminal truncated forms of proteins is of great importance, particularly in the area of development and production of protein-based drugs where the relative quantity of the intact protein and its truncated form needs to be monitored. In this work, we describe a rapid method for absolute quantification of protein mixtures containing intact and N-terminal truncated proteins. This method is based on dansylation labeling of the N-terminal amino acids of proteins, followed by microwave-assisted acid hydrolysis of the proteins into amino acids. It is shown that dansyl labeled amino acids are stable in acidic conditions and can be quantified by liquid chromatography mass spectrometry (LC–MS) with the use of isotope analog standards. 相似文献
996.
Michael A. Beckett Paul Owen Gary C. Strickland K. Sukumar Varma 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1):509-512
The interaction of benzyl alcohol with trimethoxyboroxine has been investigated by hydrogen-1 and carbon-13 NMR and IR spectroscopy. These techniques indicate formation of a weak Lewis acid/base adduct, additionally stabilized by a hydrogen-bonding interaction, which undergoes rapid ligand exchange at room temperature. The system has been modelled by the synthesis and characterization of a series of amine-triarylboroxine adducts. These adducts rapidly undergo ligand dissociation-recombination in solution with ΔG+ of ca. 40-50 kJ/mol. 相似文献
997.
K. S. Bruzik G. M. Salamończyk B. Soboń 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-4):39-42
Abstract The structure and the dynamics of D-erythrostearoyl sphingomyelin has been studied by the variable temperature wide-line 31P and high-resolution 1C CP MAS NMR apectroscopy. The results indicate the formation of the highly ordered, relaxed gelphase, and are interpreted based on the conformation of D-erytgrosphingomylin in the unaggregated state. 相似文献
998.
M. Casale P. Oliveri C. Casolino N. Sinelli P. Zunin C. Armanino M. Forina S. Lanteri 《Analytica chimica acta》2012
An authentication study of the Italian PDO (protected designation of origin) extra virgin olive oil Chianti Classico was performed; UV–visible (UV–vis), Near-Infrared (NIR) and Mid-Infrared (MIR) spectroscopies were applied to a set of samples representative of the whole Chianti Classico production area. 相似文献
999.
《Analytical letters》2012,45(5):889-899
Abstract β-naphthoxyacetic acid (NOA) residues in strawberries have been determined in acetone extracts using direct, first and second derivatives with spectrofluorimetric detection, without clean-up procedures needed. Solvent effects on the spectral characteristics of NOA solutions and their influences on the sensitivity of its variables and instrumental parameters are also studied. A detection limit of 1.14 ng/ml was achieved using the first derivative approach. Strawberries were fortified at different NOA concentrations (10 to 90 ng/ml). Recoveries averaged 87.2% (range 80.16–98.53) at the lower fortification level and 98.36% (range 97.54–99.63) for the higher fortification level. 相似文献
1000.
《Analytical letters》2012,45(8):491-495
Abstract An ion selective electrode is described for measuring the unreacted salicylate ion concentration during the electroreduction of salicylic acid. Conditions for making measurements are discussed. 相似文献