排序方式: 共有24条查询结果,搜索用时 4 毫秒
21.
J.S. Yadav P. Purushothama Rao D. Sreenu R. Srinivasa Rao V. Naveen Kumar K. Nagaiah A.R. Prasad 《Tetrahedron letters》2005,46(42):7249-7253
o-Aminoaryl ketones undergo smooth condensation with α-methylene ketones in the presence of sulfamic acid (NH2SO3H) (SA) under mild reaction conditions to afford the corresponding polysubstituted quinolines in excellent yields. The catalyst can be recovered by simple filtration and can be recycled in subsequent reactions. The method is simple, cost-effective and environmentally benign. 相似文献
22.
Ramana Jadda Sreenu Madhumanchi Roongnapa Suedee 《Journal of separation science》2019,42(24):3662-3678
In this study, we have developed a method to assess adenosine 5?‐triphosphate by adsorptive extraction using surface adenosine 5′‐triphosphate‐imprinted polymer over polystyrene nanoparticles (412 ± 16 nm) for selective recognition/separation from urine. Molecularly imprinted polymer was synthesized by emulsion copolymerization reaction using adenosine 5′‐triphosphate as a template, functional monomers (methacrylic acid, N‐isopropyl acrylamide, and dimethylamino ethylmethacrylate) and a crosslinker, methylenebisacrylamide. The binding capacities of imprinted and non‐imprinted polymers were measured using high‐performance liquid chromatography with UV detection with a detection limit of 1.6 ± 0.02 µM of adenosine 5′‐triphosphate in the urine. High binding affinity (QMIP, 42.65 µmol/g), and high selectivity and specificity to adenosine 5′‐triphosphate compared to other competitive nucleotides including adenosine 5?‐diphosphate, adenosine 5?‐monophosphate, and analogs such as adenosine, adenine, uridine, uric acid, and creatinine were observed. The imprinting efficiency of imprinted polymer is 2.11 for urine (QMIP, 100.3 µmol/g) and 2.51 for synthetic urine (QMIP, 48.5 µmol/g). The extraction protocol was successfully applied to the direct extraction of adenosine 5′‐triphosphate from spiked human urine indicating that this synthesized molecularly imprinted polymer allowed adenosine 5′‐triphosphate to be preconcentrated while simultaneously interfering compounds were removed from the matrix. These submicron imprinted polymers over nano polystyrene spheres have a potential in the pharmaceutical industries and clinical analysis applications. 相似文献
23.
K. V. Purnima D. Sreenu N. Bhasker K. Nagaiah N. Lingaiah B. V. Subba Reddy J. S. Yadav 《中国化学》2013,31(4):534-538
Three components coupling of alkyl bromide, sodium azide and alkyne has been achieved using a catalytic amount of copper‐exchanged phosphotungstic acid (Cu‐TPA) in the presence of triethyl amine in DMF to afford substituted triazoles in good yields with high selectivity. Interestingly, the coupling of alkyl azide with alkyne proceeds readily at room temperature to furnish 1,2,3‐triazoles in excellent yields. The catalyst can be recovered and reused for three to four subsequent runs with a minimal decrease of activity. The use of copper modified heteropolyacids makes this procedure simple, convenient and environmentally friendly. 相似文献
24.
Hui Zhou Sreenu R. Venumbaka John W. Fitch III Patrick E. Cassidy 《Macromolecular Symposia》2003,192(1):115-122
In order to obtain crosslinkable, low dielectric, low Tg materials, the hydrosilation polymerization was carried out in supercritical carbon dioxide (SC CO2) using Karstedt's catalyst, and a series of new fluorine-containing poly(carbosilane/siloxane) were synthesized and characterized. The molecular weights of polymers obtained in SC CO2 were notably greater than those obtained in benzene. Hydrolysis and thermal curing of these polymers leads to materials considerably higher molecular weight which retain their low Tg values. 相似文献