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81.
Some new pyridyl alcohols with the cis-bicyclo[3.3.0]octane scaffold were synthesized and used as chiral ligands for the enantioselective addition of diethylzinc to aldehydes. Ligands 4 were found to be far superior to the C2-symmetric ligands 2 in terms of enantioselectivities. Quantitative yields and enantiomeric excesses of up to 92% were obtained when the ligand 4 was used. The carbonyl function in 4 proved to be beneficial for the high enantioselectivities in the addition of diethylzinc to aldehydes. Conversion of the carbonyl group into oxime or oxime ether group led to a sort of more active ligands, which catalyzed the same reaction with rate acceleration. 相似文献
82.
Copper mediated alkyl-transfer reaction of trialkylaluminum (R3Al) with (E)-4,4-difluoro-5-hydroxyallylic alcohol derivative smoothly proceeded to give the corresponding 2-alkylated 4-fluoro-5-hydroxyhomoallylic alcohol derivative with completely Z and 2,5-syn selective manner. Regio- and stereoselective conversion of the C5-hydroxyl group of the fluoroolefin thus obtained to amino group could be achieved through one-pot mesylation and azidation reaction. 相似文献
83.
Preparation of Silver Nanoparticles through Alcohol Reduction with Organoalkoxysilanes 总被引:1,自引:0,他引:1
Hoe Jin Hah Sang Man Koo Sang Hoon Lee 《Journal of Sol-Gel Science and Technology》2003,26(1-3):467-471
Silver nanoparticles of narrow size distribution were prepared through the chemical reduction in an alcohol solution with several organoalkoxysilanes. In this system, organoalkoxysilanes served as a stabilizer, protecting silver nanoparticles from aggregation. The changes in size and morphology of colloidal silver nanoparticles were investigated with the addition of organoalkoxysilanes such as 3-aminopropyltriethoxysilane (APS), methyltriethoxysilane (MTS), phenyltrimethoxysilane (PTS), vinyltriethoxysilane (VTS), and 3-glycidoxypropyltrimethoxysilane (GPS) as stabilizers. The organic functional groups of organoalkoxysilanes interact with silver ions and clusters, which stabilize silver nanoparticles in the system. The silver nanoparticles obtained were characterized with transmission electron microscopy (TEM), UV-vis spectroscopy, etc. 相似文献
84.
85.
Three highly sensitive spectrophotometric methods for the determination of platinum(IV) have been developed, based on its colour reactions with molybdate and basic dyes (BD) in aqueous solution in the presence of poly(vinyl alcohol). Platinum(IV) reacts with molybdate and BD to form ion — association complexes of composition (BD)2[Pt (MoO4)3]. The molar absorptivities are between 6.83 × 105 and 9.51 × 105 dm3mol–1cm–1, the highest value being found with nile blue. Suitable conditions for the reactions and the effects of foreign ions were investigated. The methods can be applied to the spectrophotometric determination of trace amounts of platinum(IV) in some catalysts and ores. 相似文献
86.
在酸性介质中用氧化还原滴定法研究了铈(IV)离子在痕量铱(III)离子催化作用下,于298~313 K区间氧化四氢糠醇(THFA)的反应动力学. 结果表明,反应对铈(IV)离子为一级,对铱(III)离子也为一级,对四氢糠醇的表观反应级数为正分数. 准一级速率常数kobs随[H+]增加而增大,而随[HSO4-]增加而减小. 在氮气保护下,反应能引发丙烯腈聚合,说明在反应中有自由基产生. 通过kobs与[HSO4-]的依赖关系,找到本反应体系的动力学活性物种是Ce(SO4)2,并计算出平衡常数,速控步骤的速率常数及相应的活化参数. 相似文献
87.
碳氟醇与阴离子表面活性剂的相互作用 总被引:2,自引:0,他引:2
测定了不同比例的C_(10)_H_(21)SO_4Na-C_3F_7CH_2OH、C_7F_(15)COONa-C_3H_7CH_2OH混合水溶液的表面张力,加入C_3F_7CH_2OH可增加阴离子表面活性剂的表面活性;在表面层中,C_3F_7CH_2OH与C_(10)H_(21)SO_4Na间分子相互作用比C_3F_7CH_2OH-C_7F_(15)COONa体系弱;这是由于CF链与CH链间“互疏”作用的结果;随着C_3F_7CH_2OH浓度增加,对C_(10)H_(21)SO_4Na胶团反离子结合度也随之增加。 相似文献
88.
利用静电纺丝法与气固反应相结合, 成功地制备了硫化锌掺锰/聚乙烯醇复合纳米纤维, 并对所制备的复合物进行了表征, 探讨了复合物的结构及其性能. 相似文献
89.
Thasan Raju Sankar Manivasagan Balachandran Revathy Kumarasamy Kulangiappar Arunachalam Muthukumaran 《Tetrahedron letters》2007,48(21):3681-3684
Electrochemical oxidation of benzylic and substituted benzylic alcohols by two-phase electrolysis yields the corresponding aldehydes as products. The reaction was carried out in a single compartment cell with platinum electrodes at room temperature in chloroform using an aqueous sodium bromide solution (25%) containing a catalytic amount of HBr. The two-phase electrolysis resulted in high yields (74-96%) of benzaldehyde from primary alcohols and secondary alcohols were oxidized to the corresponding ketone but only in low yields under these conditions. 相似文献
90.
Summary A high-performance liquid chromatographic method for the separation and determination of gastrodin,p-hydroxybenzyl alcohol, vanillyl alcohol,p-hydroxylbenzaldehyde and vanillin in extract of Chinese herbal medicine tall gastrodia tuber (Chinese name: Tianma) was established.
The chromatographic conditions were optimized by means of computer-assisted method development technique. Dry-Lab software
was used to model the retention behavior of the compounds as a function of gradient conditions, based on the data from two
scouting gradient runs. Under the optimized conditions: column, Kromasil-C18, 5 μm, 15×0.46-cm; solvent A, water; solvent
B, methanol; gradient, 5/44/65/65% B at 0/9/12/15 min; flow rate, 1.00 mL min−1; temperature, ambient, the quality of tall gastrodia tubers from different sources and tianma injection were examined. 相似文献