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951.
Guoxiong Hua 《Tetrahedron》2009,65(31):6074-6987
2,4-Bis(phenyl)-1,3-diselenadiphosphetane-2,4-diselenide (Woollins’ reagent, WR) reacts with cyanamides (1a-h) in refluxing toluene to afford a series of novel selenazadiphospholaminediselenides (RR′NCN(PhP(Se)SeP(Se)Ph, R=C6H5(CH2)1-3, 4-n-C10H21C6H4 and 4-BrC6H4CH2; R′=H, CH3, C2H5 and C(O)OC2H52a-g). Post-treatment of the reaction mixture with water led to the formation of carbamidoyl(phenyl)phosphinodiselenoic acids (RR′NC(NH2)P(SeH)2Ph, R=C6H5(CH2)2-3, 4-n-C10H21C6H4 and 4-BrC6H4CH2; R′=H and CH3, 3b, 3c, 3e and 3f) and selenoureas (RR′NC(Se)NH2, R=C6H5(CH)1-2; R′=CH3 and OC(O)C2H5, 4f and 4h) in moderate to excellent yields. All new compounds are characterised spectroscopically and five X-ray crystal structures are reported. 相似文献
952.
Hisashi Shimada 《Tetrahedron》2009,65(31):6008-2622
Synthesis of 4′-substituted thymidines was investigated based on nucleophilic substitution using organosilicon and organoaluminum reagents. Two substrates having a benzenesulfonyl leaving group at the 4′-position were prepared for this purpose: 1-[4-benzenesulfonyl-3,5-bis-O-(tert-butyldimethylsilyl)-2-deoxy-α-l-threo-pentofuranosyl]thymine (8α) and the 4′-(benzenesulfonyl)thymidine derivative (8β). The reaction of 8α with organosilicon reagents (Me3SiCH2CHCH2 and Me3SiN3) in combination with SnCl4 gave preferentially the 4′-substituted β-d-isomer: the 4′-allyl (12β) and 4′-azido (15β) derivatives, respectively. The reaction of 8α with AlMe3, however, gave the 4′-methyl-α-l-isomer (16α) as the major product, presumably through an ion pair mechanism. By employing the substrate 8β in this reaction, the 4′-methylthymidine derivative (16β) was obtained exclusively in high yield. The 4′-ethyl (20β) and 4′-cyano (24β) derivatives were also synthesized by reacting 8β with the respective organoaluminum reagent. 相似文献
953.
《Mendeleev Communications》2021,31(6):839-841
The modification of Nafion® membranes with poly(diallyldimethylammonium chloride) (PDDA) in aqueous solutions of isopropanol has been investigated. A remarkable decrease in vanadyl ion permeability (by 3.5 orders of magnitude), accompanied by a decrease in proton conductivity sixfold at most, was found for Nafion membranes modified in 30–35 wt% isopropanol solutions providing a high swelling of the membranes. The Bradford reagent has been used for the detection of PDDA on the membrane surface. 相似文献
954.
The first example of enantioselective allylation of aldehydes with chiral allyl organolan-thanide reagents has been achieved in high chemical yield and moderate optical purity (up to 54% e.e.). 相似文献
955.
956.
单液滴萃取衍生化技术用于烟气中小分子醛类物质的分析 总被引:1,自引:0,他引:1
本实验利用单液滴衍生化萃取技术(EDSD),并与基质辅助激光解吸-傅立叶变换离子回旋共振质谱方法(MALDI-FTICR-MS)结合起来,建立了一种用于分析烟气中小分子醛类物质的方法.选择吉拉尔特试剂T作为衍生化试剂,烟气中的小分子醛类物质可以形成季铵盐,其在MALDI-FTMS中的灵敏度显著提高.采用上述方法实现了对单口烟气中乙醛和丙烯醛的含量的分析.该分析方法易于实现自动化,为检测卷烟烟气中小分子醛类物质提供了一种简单、快速、准确的分析方法. 相似文献
957.
Oxygenradicalsaswellas0theroxygen-derivedspeciesincludinglipidperoxides,havebeensuggestCdaspotentiallyimportantcausativeagents0fagingandvarioushumandi,...,i-3suchascancer,multiplescler0sis,Parkinson'sdisease,autoinununediseases,ischemia,anemia,seniledementiaandasbestosis.Am0ngthevari0usradicals,thehydroxylradical(OH)ispresumedtoplayacentralroleduetoitSstr0ngactivity'.TheimPortanceofremovingexcessiveactiveoxygenspeciesfromlivingorganismsisbecondngincreasinglyrec0gnized,t0getherwithagrowingint… 相似文献
958.
建立了使用离子对试剂同时检测啤酒中异α-酸、二氢异α-酸、四氢异α-酸和六氢异α-酸的反相高效液相色谱法。实验采用四丁基氢氧化铵-磷酸缓冲液(pH调至7.2)-乙腈为流动相,Xterra RP C18(4.6×150 mm,5μm)色谱柱,等度洗脱,实现这4种异构化α-酸的所有组分的有效分离测定。各组分色谱峰保留时间的RSD为0.1%~0.3%,峰面积的RSD为0.5%~1.7%(n=7),重现性和线性关系较好;4种异构化α-酸的加标回收率为96%~108%。该方法无需样品处理,简便易行,可用于分析啤酒中所含异构化α-酸的种类和含量。 相似文献
959.
Photosensitized degradation of organic pollutants in water: processes and analytical applications 总被引:5,自引:0,他引:5
Photosensitized degradation has been used to remove a broad range of organic pollutants, generally with mineralization to CO2 and other inorganic products such as Cl− and
. TiO2 and Fe3+ are the photosensitizers mainly used to accelerate the degradation of persistent organic chemicals. Various analytical techniques were used to identify the degradation products and to monitor the degradation kinetics. Chromatographic techniques such as high-performance liquid chromatography (HPLC), gas chromatography (GC) and ion-exchange were used. Other analytical techniques, such as total organic carbon analysis, UV–visible spectrophotometry, spectrofluorimetry, and potentiometry, were also used. When the photodegradation is carried out in water, extraction methods such liquid–liquid extraction or solid-phase extraction need to be used, followed by GC or HPLC analysis. We review the analytical methods used for the identification of the products formed in photodegradation studies. Kinetic studies of the degradation are also reported. 相似文献
960.
以三氟丙烯和溴为原料加成制得1,2-二溴三氟丙烷,脱溴化氢得到2-溴三氟丙烯,再在一定条件下合成2-溴三氟丙烯的格氏试剂(三氟异丙烯基溴化镁),与CO2反应最终生成1-溴-2-三氟甲基丙酸。 用碳酸钠溶液萃取的方法得到0.8 g产品,纯度为99.6%,收率为3.6%。 对产物进行了MS、IR、1H NMR和13C NMR等表征,并分析了主要副产物1,2-二氟丙二烯和2,3-二三氟甲基-1,3-丁二烯及其与未反应的2-溴三氟丙烯间的[2+2]或[2+4]环加成反应产物。 确定以2-溴三氟丙烯为原料经格氏反应制羧酸较好的反应条件为:以THF为溶剂,1,2-二溴乙烷作引发剂,制备格氏试剂温度为30 ℃,CO2与格氏试剂反应温度为0 ℃。 相似文献