Synthesis of Urea Derivatives from CO₂ and Silylamines

Abstract

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 conditions to afford the thermodynamically favored urea and disilyl ether.

Study of the Cycloaddition of CO2 with Styrene Oxide Over Six‐Connected spn Topology MOFs (Zr, Hf) at Room Temperature

“…As a complementary technology, carbon capture and utilization (CCU) have the potential to commercialize CO 2 to offset the capture cost and bring economic benefits, [1,2] and are widely favored by researchers. At present, there have been reports on the utilization of CO 2 to prepare carbonate, [3,4] urea derivatives, [5,6] methanol, [7,8] formic acid [9,10] and other chemical products.…”

Highly Selective Electrochemical Synthesis of Urea Derivatives Initiated from Oxygen Reduction in Ionic Liquids

“…A Bruker 200 MHz NMR spectrometer was used to record 13 C isotope products using 13 C NMR. Both the 13 C salt product and 13 C urea product were prepared using the same technique as 12 C products but substituting 12 CO 2 with 13 CO 2 , supplied from Sigma-Aldrich (99.0%). In this case, a magnetic stir bar was added to the reaction vessel since the 13 CO 2 gas was a low-pressure gas incapable of bubbling into the mixture.…”

“…The standard Gibbs free energy changes for reactions (1) and (2) are −23.8 and +16.7 kJ, respectively, at 25 °C and 1 bar. As a kinetically slow process, reaction (2) is thermodynamically infeasible at the ambiance; thus, significant external energy and catalysts are needed . This reaction is initiated from the carbamate salt form, at which point the amine group is required to nucleophilically attack the carbonyl group.…”

“…As a kinetically slow process, reaction (2) is thermodynamically infeasible at the ambiance; thus, significant external energy and catalysts are needed. 12 This reaction is initiated from the carbamate salt form, at which point the amine group is required to nucleophilically attack the carbonyl group. Strong bases such as CsOH, Cs 2 CO 3 , KOH, and [BMIM]OH are utilized in the chemical process to generate negatively charged R-NH – or R-NH* radical.…”

Recent Advances in Electrocatalysts for Sustainable Electrosynthesis of Ammonia and Urea from Ambient Nitrite Reduction and C–N Coupling

“…However, the nitrate reduction usually suffers from low selectivity and would induce nitrite accumulation during the long-term operation . Therefore, NO 2 RR should be much more practical in industry and deserves to be studied. − Furthermore, the introduction of CO 2 during the NO 2 RR process would trigger C–N coupling and generate urea with higher added value. ,− In industry, urea is the downstream product of NH 3 and about 80% of global NH 3 produced is further used to synthesize CO­(NH 2 ) 2 . , The process is also energy intensive (150–200 °C, 150–250 bar), resulting in an energy consumption exceeding 21 billion gJ ton –1 equivalent of CO­(NH 2 ) 2 produced. − In this context, coreduction of harmful CO 2 and NO 2 – and selective transformation to valuable CO­(NH 2 ) 2 would effectively skip the energy-intensive process and provide a environmentally friendly production pathway through the utilization of renewable energy sources.…”