- Synthesis of urea derivatives from CO2 and amines catalyzed by polyethylene glycol supported potassium hydroxide without dehydrating agents
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Polyethylene glycol supported potassium hydroxide (KOH/PEG1000) was developed as a recyclable catalyst for facile synthesis of urea derivatives from amines and CO2 without utilization of additional dehydrating agents. Primary aliphatic amines, secondary aliphatic amines, and diamines can be converted into the corresponding urea derivatives in moderate yields. Furthermore, the catalyst can be recovered after a simple separation procedure, and reused over 5 times with retention of high activity. Georg Thieme Verlag Stuttgart.
- Kong, De-Lin,He, Liang-Nian,Wang, Jin-Quan
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- Efficient Reversible Hydrogen Carrier System Based on Amine Reforming of Methanol
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A novel hydrogen storage system based on the hydrogen release from catalytic dehydrogenative coupling of methanol and 1,2-diamine is demonstrated. The products of this reaction, N-formamide and N,N′-diformamide, are hydrogenated back to the free amine and methanol by a simple hydrogen pressure swing. Thus, an efficient one-pot hydrogen carrier system has been developed. The H2 generating step can be termed as "amine reforming of methanol" in analogy to the traditional steam reforming. It acts as a clean source of hydrogen without concurrent production of CO2 (unlike steam reforming) or CO (by complete methanol dehydrogenation). Therefore, a carbon neutral cycle is essentially achieved where no carbon capture is necessary as the carbon is trapped in the form of formamide (or urea in the case of primary amine). In theory, a hydrogen storage capacity as high as 6.6 wt % is achievable. Dehydrogenative coupling and the subsequent amide hydrogenation proceed with good yields (90% and >95% respectively, with methanol and N,N′-dimethylethylenediamine as dehydrogenative coupling partners).
- Kothandaraman, Jotheeswari,Kar, Sayan,Sen, Raktim,Goeppert, Alain,Olah, George A.,Prakash, G. K. Surya
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supporting information
p. 2549 - 2552
(2017/03/01)
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- Polynuclear Gold [AuI]4, [AuI]8, and Bimetallic [AuI4AgI] Complexes: C?H Functionalization of Carbonyl Compounds and Homogeneous Carbonylation of Amines
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The synthesis of tetranuclear gold complexes, a structurally unprecedented octanuclear complex with a planar [AuI8] core, and pentanuclear [AuI4MI] (M=Cu, Ag) complexes is presented. The linear [AuI4] complex undergoes C?H functionalization of carbonyl compounds under mild reaction conditions. In addition, [AuI4AgI] catalyzes the carbonylation of primary amines to form ureas under homogeneous conditions with efficiencies higher than those achieved by gold nanoparticles.
- Smirnova, Ekaterina S.,Mu?oz Molina, José M.,Johnson, Alice,Bandeira, Nuno A. G.,Bo, Carles,Echavarren, Antonio M.
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supporting information
p. 7487 - 7491
(2016/07/06)
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- Ruthenium-Catalyzed Urea Synthesis Using Methanol as the C1 Source
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An unprecedented protocol for urea synthesis directly from methanol and amine was accomplished. The reaction is highly atom-economical, producing hydrogen as the sole byproduct. Commercially available ruthenium pincer complexes were used as catalysts. In addition, no additive, such as a base, oxidant, or hydrogen acceptor, was required. Furthermore, unsymmetrical urea derivatives were successfully obtained via a one-pot, two-step reaction.
- Kim, Seung Hyo,Hong, Soon Hyeok
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supporting information
p. 212 - 215
(2016/02/03)
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- Efficient copper(II)-catalyzed transamidation of non-activated primary carboxamides and ureas with amines
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Amid(e) them all: Primary carboxamides and ureas react with aromatic and aliphatic amines in the presence of a copper catalyst to give a wide range of functionalized amides (see scheme). Copyright
- Zhang, Min,Imm, Sebastian,Baehn, Sebastian,Neubert, Lorenz,Neumann, Helfried,Beller, Matthias
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supporting information; experimental part
p. 3905 - 3909
(2012/06/04)
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- Synthesis of urea derivatives from amines and CO2 in the absence of catalyst and solvent
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Urea derivatives are obtained in mild to good yield from the reactions of primary aliphatic amines with CO2 in the absence of any catalysts, organic solvents or other additives. To optimize reaction conditions, experimental variables including temperature, pressure, the concentration of amine, reaction time etc. were studied. Satisfactory yields were obtained at the optimized conditions that are comparable to the presence of catalyst and solvent. The preliminary investigation of the reaction mechanism showed that alkyl ammonium alkyl carbamate was quickly formed as the intermediate, and then the final product was formed by the intramolecular dehydration.
- Wu, Chaoyong,Cheng, Haiyang,Liu, Ruixia,Wang, Qiang,Hao, Yufen,Yu, Yancun,Zhao, Fengyu
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experimental part
p. 1811 - 1816
(2011/02/22)
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- Bifunctional Chiral Auxiliaries 5: The Synthesis of 1,3-Diacylimidazolidine-2-thiones and 1,3-Diacylimidazolidin-2-ones from 1,2-Diamines
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Although 1,2-diamines fail to cyclise with urea, phosgene or 1,1'-carbonyl diimidazole, they react with carbon disulphide to give the corresponding imidazolidine-2-thiones.These undergo clean diacylation to give 1,3-diacylimidazolidine-2-thiones which are
- Davies, Stephen G.,Mortlock, Andrew A.
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p. 4419 - 4438
(2007/10/02)
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- Bifunctional chiral auxiliaries 2: The synthesis of 1,3-diacylimidazolidin-2-ones from 1,2-diamines
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The title compounds are readily prepared in three steps via the corresponding 1,3-diacylimidazolidine-2-thiones. The final step involves the novel use of mercury (II) acetate for the conversion of thioureas to ureas.
- Davies,Mortlock
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p. 4791 - 4794
(2007/10/02)
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