塑料是一种多功能材料,可为各个行业提供轻质、耐用且经济实惠的解决方案。然而,它们的不可降解特性在其使用寿命结束时带来了挑战。本研究提出了一种创新的羰基萃取方法,利用废弃的聚(双酚 A 碳酸酯)(PC)作为反应前体来合成活性呋喃,作为光开关 Stenhouse 加合物的前体。这种创新的化学策略不仅产生了N,N'-功能化巴比妥酸盐,而且还为传统合成方法提供了一种环保且经济高效的替代方案。本文提出的方法不仅通过在绿色条件下将废弃聚碳酸酯重新用作羰基等价物来促进可持续性,而且还产生了可重复使用的双酚A(BPA)。此外,衍生的活化呋喃通过在胺化聚合物表面形成有色的供体-受体斯滕豪斯加合物(DASA)来展示其功能。这项工作展示了从线性塑料经济向循环经济的转变,凸显了塑料废物作为创造具有改进性能的材料的资源的潜力。
Synthesis of Urea Derivatives from CO
<sub>2</sub>
and Silylamines
作者:Maotong Xu、Andrew R. Jupp、Maegan S. E. Ong、Katherine I. Burton、Saurabh S. Chitnis、Douglas W. Stephan
DOI:10.1002/anie.201900058
日期:2019.4.16
A series of thirty‐three N,N′‐diaryl, dialkyl, and alkyl‐aryl ureas have been prepared in pyridine or toluene by reaction of silylamines with CO2. This protocol is shown to provide facile access to 13C‐labeled ureas, as well as chiral and macrocyclic ureas. These reactions proceed through initial generation of the corresponding silylcarbamates, which subsequently react with silylamine under thermal
A ligand-free palladium-catalyzed aerobic oxidative carbonylation of amines for the synthesis of ureas, particular unsymmetrically N,N′-disubstituted ureas, which cannot be accessed by any other palladium-catalyzed oxidative carbonylation of amines to date, is presented. An array of symmetrical and unsymmetrical ureas were straightforwardly synthesized by using inexpensive, readily available, stable
observed in situ, which resulted in the formation of CO and dimethylamine. The scope of this new mode of bond activation is extended to the synthesis of urea derivatives from amines using DMF as a carbon monoxide (CO) surrogate. This catalytic protocol allows the synthesis of simple and functionalized urea derivatives with liberation of hydrogen, devoid of any stoichiometric activating reagents, and avoids
作者:Phillip A. Shelton、Yue Zhang、Thi Hoang Ha Nguyen、Lisa McElwee-White
DOI:10.1039/b819891h
日期:——
Oxidative carbonylation of amines using NaIO4 as the oxidant and NaI as a promoter affords good to excellent yields of ureas from primary amines in the absence of transition metalcatalysts.
使用 NaIO4 作为氧化剂和 NaI 作为促进剂的胺的氧化碳基化反应,可以在没有过渡金属催化剂的情况下,从初级胺中获得良好到优异的尿素产率。
Unprecedented Catalytic Hydrogenation of Urea Derivatives to Amines and Methanol
Indirect CO2 hydrogenation: Hydrogenation of ureaderivatives to the corresponding amines and methanol is reported (see picture). The reaction is catalyzed by a bipyridine‐based tridentate PNN Ru(II) pincer complex and proceeds under mild, neutral conditions using 13.6 atm of H2. A mild approach is offered for the indirect hydrogenation of CO2 to methanol as ureaderivatives are available from CO2