1111-78-0Relevant articles and documents
Kinetics of the NH3and CO2 solid-state reaction at low temperature
Noble,Theule,Duvernay,Danger,Chiavassa,Ghesquiere,Mineva,Talbi
, p. 23604 - 23615 (2014)
Ammonia and carbon dioxide play an important role in both atmospheric and interstellar ice chemistries. This work presents a theoretical and experimental study of the kinetics of the low-temperature NH3 and CO2 solid-state reaction in ice films, the product of which is ammonium carbamate (NH4+NH2COO-). It is a first-order reaction with respect to CO2, with a temperature-dependent rate constant fitted to the Arrhenius law in the temperature range 70 K to 90 K, with an activation energy of 5.1 ± 1.6 kJ mol-1 and a pre-exponential factor of 0.09 +1.1-0.08 s-1. This work helps to determine the rate of removal of CO2 and NH3, via their conversion into ammonium carbamate, from atmospheric and interstellar ices. We also measure first-order desorption energies of 69.0 ± 0.2 kJ mol-1 and 76.1 ± 0.1 kJ mol-1, assuming a pre-exponential factor of 1013 s-1, for ammonium carbamate and carbamic acid, respectively.
Catalytic Urea Synthesis from Ammonium Carbamate Using a Copper(II) Complex: A Combined Experimental and Theoretical Study
Dennis, Donovan,Ekmekci, Merve B.,Hanson, Danielle S.,Paripati, Amay,Wang, Yigui,Washburn, Erik,Xiao, Dequan,Zhou, Meng,Zhou, Xinrui
, p. 5573 - 5589 (2021)
The synthesis of urea fertilizer is currently the largest CO2 conversion process by volume in the industry. In this process, ammonium carbamate is an intermediate en route to urea formation. We determined that the tetraammineaquacopper(II) sulfate complex, [Cu(NH3)4(OH2)]SO4, catalyzed the formation of urea from ammonium carbamate in an aqueous solution. A urea yield of up to 18 ± 6% was obtained at 120 °C after 15 h and in a high-pressure metal reactor. No significant urea formed without the catalyst. The urea product was characterized by Fourier transform infrared (FT-IR), powder X-ray diffraction (PXRD), and quantitative 1H{13C} NMR analyses. The [Cu(NH3)4(OH2)]SO4 catalyst was then recovered at the end of the reaction in a 29% recovery yield, as verified by FT-IR, PXRD, and quantitative UV-vis spectroscopy. A precipitation method using CO2 was developed to recover and reuse 66 ± 3% of Cu(II). The catalysis mechanism was investigated by the density functional theory at the B3LYP/6-31G*? level with an SMD continuum solvent model. We determined that the [Cu(NH3)4]2+ complex is likely an effective catalyst structure. The study of the catalysis mechanism suggests that the coordinated carbamate with [Cu(NH3)4]2+ is likely the starting point of the catalyzed reaction, and carbamic acid can be involved as a transient intermediate that facilitates the removal of an OH group. Our work has paved the way for the rational design of catalysts for urea synthesis from the greenhouse gas CO2.
New attempt for CO2 utilization: One-pot catalytic syntheses of methyl, ethyl and n-butyl carbamates
Li, Jian,Qi, Xiujuan,Wang, Liguo,He, Yude,Deng, Youquan
, p. 1224 - 1227 (2011)
The direct production of methyl, ethyl and n-butyl carbamates (MC, EC and BC) from NH3, CO2 and alcohols could efficiently be catalyzed by V2O5, and ca. 11-25% yields with 98% selectivity for alkyl carbamates could be obtained. The catalyst could be recycled six times without obvious decrease in catalytic activity. XRD and XPS analysis showed that in-situ produced (NH4)2V 3O8 was the catalytically active species.
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Blair
, p. 89 (1926)
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Direct NHC-catalysed redox amidation using CO2 for traceless masking of amine nucleophiles
Davidson, Robert W. M.,Fuchter, Matthew J.
supporting information, p. 11638 - 11641 (2016/10/04)
The N-heterocyclic carbene (NHC)-catalysed redox amidation reaction is poorly developed and usually requires catalytic co-additives for electron-rich amine nucleophiles. We report a masking strategy (using CO2) that couples release of the free amine nucleophile to catalytic turnover, and in doing so, enables direct catalytic redox amidation of electron-rich amines.
