Cerium ammonium nitrate-catalyzed aerobic oxidative coupling of dithiocarbamates: facile synthesis of thioureas and bis(aminothiocarbonyl)disulfides
作者:Tian-Tian Li、Xiang-Hai Song、Mei-Shuang Wang、Ning Ma
DOI:10.1039/c4ra04628e
日期:——
Diverse disubstituted and trisubstituted thioureas were synthesized by the condensation of dithiocarbamate TEA (or DABCO) salts and amines using cerium ammonium nitrate (CAN) as a catalyst in high yields at room temperature. It is a one-pot method and it is unnecessary to isolate isothiocyanates. This reaction probably took place through nucleophilic addition of amines to isothiocyanates, which were generated by oxidative coupling of dithiocarbamates and the following decomposition of bis(aminothiocarbonyl)disulfides. When secondary amines and CS2 served as the reactants, bis(aminothiocarbonyl)disulfides were obtained via tandem nucleophilic addition/oxidative coupling reactions in moderate to excellent yields. In all the coupling reactions, the oxidant was air and CAN possibly acted as an SET catalyst.
Experimental and theoretical studies of substituent effects in hydrogen bond based molecular recognition of a zwitterion by substituted arylureas
作者:Craig S. Wilcox、Eun-il Kim、David Romano、Lung Huang Kuo、Arthur L. Burt、Dennis P. Curran
DOI:10.1016/0040-4020(94)00921-g
日期:1995.1
Electron withdrawing groups have a strong effect on hydrogenbonding to aryl ureas. The effect of para substituents modestly exceeds the effect of meta substituents. Among common substituent parameters, σ− (ϱ = 1.77, r2 = 0.988) is found to be the best predictor for the observed effects of para substituents in aryl ureas. Semi-empirical and ab initio methods are used to calculate charge distributions
Use of sulfur and selenium compounds as precursors to nanostructured materials
申请人:THE TRUSTEES OF COLUMBIA UNIVERSITY IN THE CITY OF NEW YORK
公开号:US10253256B2
公开(公告)日:2019-04-09
The presently disclosed subject matter provides processes for preparing nanocrystals, including processes for preparing core-shell nanocrystals. The presently disclosed subject matter also provides sulfur and selenium compounds as precursors to nanostructured materials. The presently disclosed subject matter also provides nanocrystals having a particular particle size distribution.