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141.
A simple and novel flow‐injection chemiluminescence (FI‐CL) method was established for the determination of 2‐Methoxyestradiol (2‐ME) in pharmaceutical preparations and biological fluids. The method was based on the significant enhancement of the CL from the KMnO4‐Na2SO3 reaction by 2‐ME in acidic medium. Under optimized conditions, the CL intensity was correlated linearly with concentration of 2‐ME in the range of 5.0 × 10?8‐5.0 × 10?6 M (r = 0.9995). The detection limit (3σ) of 2‐ME was 7.5 × 10?9 M and the relative standard deviation was 0.8% at 5.0 × 10?7 M 2‐ME (n = 8). The proposed method was successfully applied for the flow‐injection CL determination of 2‐ME in pharmaceutical preparations and biological fluids with the recoveries from 92.4 to 106.8%. The possible CL reaction mechanism was also discussed briefly. 相似文献
142.
The reduction of a variety of carbonyl compounds was efficiently carried out with NaBH4/DOWEX(R)50WX4 system. The reactions were performed to give the corresponding alcohols derivatives in perfect yields in THF at room temperature. Reduction of acyloins and a‐diketones by this reducing system produced efficiently the corresponding vicinal diols. Also, the reduction of aldehydes over ketones has been accomplished successfully by this system. Regioselectivity of this system was also investigated with exclusive 1,2‐reduction of conjugated carbonyl compounds to their corresponding allylic alcohols in high to excellent yields. 相似文献
143.
Frank Kubel Nicole Wandl Mariana Pantazi Vincenza D'Anna Hans Hagemann 《无机化学与普通化学杂志》2013,639(6):892-898
The crystal structures of the M2NaIO6 series (M = Ca, Sr, Ba), prepared at 650 °C by ceramic methods, were determined from conventional laboratory X‐ray powder diffraction data. Synthesis and crystal growth were made by oxidizing I– with O2(air) to I7+ followed by crystal growth in the presence of NaF as mineralizator, or by the reaction of the alkali‐metal periodate with the alkaline‐earth metal hydroxide. All three compounds are insoluble and stable in water. The barium compound crystallizes in the cubic space group Fm3m (no. 225) with lattice parameters of a = 8.3384(1) Å, whereas the strontium and calcium compounds crystallize in the monoclinic space group P21/c (no. 14) with a = 5.7600(1) Å, b = 5.7759(1) Å, c = 9.9742(1) Å, β = 125.362(1)° and a = 5.5376(1) Å, b = 5.7911(1) Å, c = 9.6055(1) Å, β = 124.300(1)°, respectively. The crystal structure consists of either symmetric (for Ba) or distorted (for Sr and Ca) perovskite superstructures. Ba2NaIO6 contains the first perfectly octahedral [IO6]5– unit reported. The compounds of the ortho‐periodates are stable up to 800 °C. Spectroscopic measurements as well as DFT calculations show a reasonable agreement between calculated and observed IR‐ and Raman‐active vibrations. 相似文献
144.
The determination of the phase diagram of the binary system sodium perchlorate – water is reported. Beside the eutectic point, two polymorph crystal structures of sodium perchlorate dihydrate were determined. The two crystal structures are discussed, compared to each other and to other known sodiumhalide dihydrate crystal structures. The two polymorphs of the perchlorate dihydrate represent the two variants of connected octahedra in the layer structure found for sodium halide dihydrates. 相似文献
145.
In an environmentally benign solvent-free system, oximes and hydrazones are rapidly transformed into parent carbonyl compounds using peroxymonosulfate on silica gel under microwave irradiation in good to excellent yields. 相似文献
146.
Yong Lin Kunbo Wang Yujun Yan Haiyan Lin Bin Peng Zhonghua Liu 《Journal of separation science》2013,36(18):3026-3034
SDS and sodium deoxycholate (SDC) as two representative detergents have been widely used in LC–MS/MS‐based shotgun analysis of membrane proteomes. However, some inherent disadvantages limit their applications such as interference with MS analysis or their weak ability to disrupt membranes. To address this, the combinative application of SDS and SDC was developed and evaluated in our study, which comprehensively used the strong ability of SDS to lyse membranes and solubilize hydrophobic membrane proteins, and the high efficiencies of an optimized acetone precipitation method and SDC in sample clean‐up, protein recovery, and redissolution and digestion of precipitated proteins. The comparative study using a rat‐liver‐membrane‐enriched sample showed that, compared with other three commonly used methods including the filter‐aided sample preparation strategy, the combinative method not only increased the identified number of total proteins, membrane proteins, and integral membrane proteins by an average of 19.8, 23.9, and 24.8%, respectively, but also led to the identification of the highest number of matching peptides. All these results demonstrate that the method yielded better recovery and reliability in the identification of the proteins especially highly hydrophobic integral membrane proteins than the other three methods, and thereby has more potential in shotgun membrane proteomics. 相似文献
147.
Multiple emulsions stabilized by colloidal microcrystalline cellulose (CMCC, Avicel RC591) at the w/o and o/w interfaces, and by the addition of Span 80 or Span 85 at the w/o interface, were studied by means of brightfield microscopy, freeze-etch electron microscopy, droplet size distribution analysis and rheologic measurements. Stable multiple emulsions were prepared by incorporation of sodium chloride in the innermost aqueous phase, thereby creating an osmotic gradient preventing loss of the inner aqueous phase to the external aqueous phase. Freeze-etch electron microscopy of the multiple emulsions indicated the presence of a network of microcrystalline cellulose at the outer o/w interface. It may be assumed that the surfactant directly stabilized the w/o interface by adsorption at the interface, as well as indirectly by facilitating wetting of the microcrystalline cellulose by the oil. From rheologic measurements, the existence of a three-dimensional network in the external aqueous phase was indicated by the considerable degrees of thlxotropy and significant static yield values of these multiple emulsions. 相似文献
148.
Feng Yan Xian‐Guang Wang Zhen‐Quan Li Lu Zhang Jia‐Yong Yu 《Journal of Dispersion Science and Technology》2013,34(3):387-396
A series of anionic N‐acyltaurate surfactants, side chain containing aromatic nucleus (abbreviated as SAATT), were synthesized via Williamson reaction, hydrolyzation, and acylation. Krafft temperatures and surface properties of these surfactants at 30°C, that is, critical micelle concentration, cmc, surface excess concentration, Γmax, surface area demand per molecule, A min, efficiency in surface tension reduction, pC20, effectiveness in surface tension reduction, πcmc, and cmc/C20 parameter were determined. It was shown that these surfactants exhibit good solubility which was confirmed by measuring Krafft temperature. The cmc of SAATT was much smaller than that of conventional surfactants with similar effective carbon numbers, and shifted to lower concentration with increasing hydrocarbon chain length. In addition, the γcmc decreased with decrease in Γmax. The pC20 and the cmc/C20 got larger with the increase in hydrocarbon chain length. From the fluorescence intensity ratios of I 1 (373 nm) and I 3 (384 nm) using pyrene as a probe, it was indicated that the molecules of SAATT formed loose micelles with a broad size distribution. 相似文献
149.
Mukund P. Sibi Chad C. Stessman Jeffrey A. Schultz James W. Christensen Jianliang Lu Mali Marvin 《合成通讯》2013,43(8):1255-1264
Carboxylic acids can be converted to their corresponding N-methoxy-N-methylamides in high yields using 2-chloro-1-methylpyridinium iodide as the coupling agent. The reaction proceeds without racemization when chiral carboxylic acids are used as the starting material. 相似文献
150.
I. F. Lutsenko 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1):99-107
Abstract The past two decades have brought us a snowballing development of organophosphorus chemistry. Indeed organophosphorus compounds have found wide practical application (in agriculture, petroleum industry, as drugs, etc.) and continue to afford promising objects for the study of theoretical matters such as tautomerism, ambiphilicity, ambidenticity, and other problems of organic chemistry. On the other hand, however impressive this progress may be, the search for new methods of synthesis, improving the known methods and forecasting new types of organophosphorus compounds remain as challenging problems as before. 相似文献