排序方式: 共有89条查询结果,搜索用时 125 毫秒
1.
Biswanath Das Katta Venkateswarlu Maddeboina Krishnaiah Harish Holla 《Tetrahedron letters》2006,47(49):8693-8697
A simple, efficient and rapid method has been developed for high-yielding regioselective nuclear monobromination of aromatic and heteroaromatic compounds using NBS in the presence of sulfonic-acid-functionalized silica at room temperature. The catalyst works under heterogeneous conditions and can be recycled. 相似文献
2.
氧化反应是有机化学中的一种重要反应类型,也是有机化学、化学工程和生物学家们研究的重点之一.但因其机理复杂,至今未见到用热动力学理论探索氧化反应体系的报道. N溴代丁二酰亚胺(NBS)是良好的溴化试剂,在不同反应条件下,它既可和不饱和键发生加成反应,也可在水溶液中作为次溴酸的来源,还可作为有效的氧化剂和脱氢剂.Reich和Reichstein首先报道了用N溴代乙酰亚胺将仲醇缓慢氧化为酮,Fieser等人报道了NBS的氧化作用.本文用RD-1型热导式自动量热计研究了35℃下NBS氧化异丙醇及环己醇2个反应体系,计算了反应速率常数,对反应的动力学及其机理提出了较合理的解释. 相似文献
3.
A novel and sensitive chemiluminescence (CL) method for the determination of aminomethylbenzoic acid and aminophylline coupled with flow-injection analysis (FIA) technique is developed in this paper. It is based on the inhibition effect of the studied drugs on the chemiluminescence emission of N-bromosuccinimide-luminol (NBS-luminol) system. Under the optimum conditions, the decreased CL intensity is linear with the concentration of aminomethylbenzoic acid in the range of 2×10−8 to 1.0×10−6 g ml−1 and with the concentration of aminophylline in the range of 1×10−7 to 7.0×10−6 g ml−1, respectively. The detection limit is 7.0×10−9 g ml−1 for aminomethylbenzoic acid (3σ) and 3.4×10−8 g ml−1 for aminophylline (3σ). The relative standard deviations (R.S.D.) for 11 parallel measurements of 2.0×10−7 g ml−1 aminomethylbenzoic acid and 1.0×10−6 g ml−1 aminophylline are 2.6 and 3.0%, respectively. The proposed methods have been applied for the determination of the studied drugs in their pharmaceutical formulations with satisfactory results. The possible use of the proposed system for the determination of aminomethylbenzoic acid in plasma sample was also tested. The possible inhibition mechanism of aminomethylbenzoic acid and aminophylline on luminol-NBS system was discussed briefly. 相似文献
4.
Suman L. Jain 《合成通讯》2013,43(10):1459-1462
The oxidation of a variety of benzylic and secondary alcohols was achieved in excellent yields using an NBS/NH4Cl system in aqueous acetonitrile (CH3CN‐H2O; 7/3 v/v) at 80°C under very mild conditions. 相似文献
5.
Whereas the oxidative esterification of benzaldehyde to methyl benzoate with N-bromosuccinimide (NBS)-pyridine requires dark conditions and 5 equivalents each of NBS and K2CO3 and gave only moderate yield (52%) of the product (McDonald et al. J. Org. Chem. 1989, 54, 1213), simple change of base to pyridine gave the desired product in 83% gas chromatographic yield with only 1 equivalent each of NBS and pyridine. Moreover, the reaction could be conducted without exclusion of light. Aromatic aldehydes bearing electron-withdrawing substituents at meta/para position yielded the corresponding methyl esters in still better yields. Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications® to view the free supplemental file. 相似文献
6.
A chemoselective, straightforward, and rapid method for thioacetalization of aldehydes by use of 1,2‐ethandithiol and a catalytic amount of N‐bromosuccinimide under solvent‐free conditions is reported. The reaction takes place in excellent yields and short reaction times. 相似文献
7.
Methyl 6‐O‐p‐nitrobenzoyl‐β‐d‐glucoside was synthesized by reacting methyl 4,6‐O‐p‐nitrobenzylidine‐β‐d‐glucoside with N‐bromosuccinimide (NBS). First, methyl β‐d‐glucoside was converted into methyl 4,6‐O‐p‐nitrobenzylidine‐β‐d‐glucoside with p‐nitrobenzaldehyde. Later, methyl 4,6‐O‐p‐nitrobenzylidine‐β‐d‐glucoside was opened oxidatively with NBS to give methyl 6‐O‐p‐nitrobenzoyl‐β‐d‐glucoside. 相似文献
8.
Chao He Xiaohui Zhang Ruofeng Huang Jing Pan Jiaqiang Li Xuege Ling Yan Xiong Xiangming Zhu 《Tetrahedron letters》2014
Under open-flask conditions, an efficient method to assemble a series of diversely functionalized diarylketones in the presence of commercially available NBS has been developed. Yields of up to 99% have been achieved employing diarylmethanes as starting material. Based on 18O-labeled experiment, the addition of stoichiometric water eventually leads to excellent yields in all carbonylation cases. 相似文献
9.
A hybrid catalyst has been prepared by incorporating sulfonic acid onto cobalt ferrite magnetic nanoparticles. The catalyst was successfully applied for rapid (20?min) synthesis of α,α-dibromoketones directly from alkynes and NBS. The reaction works well in the presence of 10?wt% of the catalyst at room temperature to produce the desired products in high yield. The catalyst could be recovered using an external magnet and reused without appreciable change in activity. 相似文献
10.