1111-78-0Relevant academic research and scientific papers
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.
Carbamic acid: Molecular structure and IR spectra
Khanna,Moore
, p. 961 - 967 (1999)
Infrared absorption spectra of mixed H2O, NH3 and 12CO2/13CO2 ices subjected to 1 MeV proton irradiation were investigated. The results of analyses of the spectra suggest formation of carbamic acid at low temperatures. The stability of this compound in the solid phase is attributed to intermolecular hydrogen bonding of the zwitter-ion (NH3+COO-) structure.
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.
First characterisation of two important postulated intermediates in the formation of a HydT DNA lesion, a thymidine oxidation product
Psykarakis, Emmanuel E.,Chatzopoulou, Elli,Gimisis, Thanasis
, p. 2289 - 2300 (2018/04/05)
A number of environmental pollutants and endogenous oxidation agents form 1-(2-deoxy-β-d-ribofuranosyl)-5-hydroxy-5-methylhydantoin (HydT), an important DNA lesion resulting from thymidine oxidation. In this paper, two intermediates, postulated in the formation of HydT, have been characterised for the first time. The first, N1-formyl-N3-pyruvoylurea intermediate, was produced by the ozonolysis reaction of 2′,3′,5′-tri-O-acetylribo-, 3′,5′-di-O-TBS- and N3,O3′,O5-tribenzyl-protected thymidines and was shown to produce, upon decomposition and depending on the protecting group and the conditions, HydT alone, or together with protected-β-d-ribofuranosyl-N1-formylurea and formamide products. In addition, the second and long sought, open-chain-pyruvoylurea intermediate, was produced through de novo synthesis in protected β-d-ribofuranosyl-, 2-deoxy-β-d-ribofuranosyl- and 2-deoxy-β-d-ribopyranosyl systems. The conditions that induce the cyclization to the hydantoin ring of HydT have been determined. The chemistry utilised in the de novo synthesis is suitable for generating isotopically labelled HydT, as a reference in isotope-dilution-aided quantification of DNA damage.
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.
HIGH-YIELD PROCESS FOR THE SYNTHESIS OF UREA
-
Paragraph 0086-0127, (2014/04/03)
A process for the direct synthesis of urea from ammonia and carbon dioxide at high pressures and temperatures, with the formation of ammonium carbamate as intermediate, comprising a decomposition step of the ammonium carbamate and stripping of the gases formed, operating substantially at the same pressure as the synthesis step, wherein the recycled liquid streams are fed, at least partially, to the same decomposition and stripping step after being preheated by heat exchange with a stream included in the high-pressure synthesis cycle.
A process for synthesis of urea and a related arrangement for a reaction section of a urea plant
-
Paragraph 0079, (2013/06/27)
A process for synthesis of urea and a related reaction section of a urea plant, where: ammonia and carbon dioxide are reacted in a liquid phase in a first reaction zone (S1) and heat (Q1) is withdrawn from said first reaction zone to promote the formation of ammonium carbamate, the liquid product (103) from said first reaction zone is then passed to a second reaction zone (S2) distinguished from said first reaction zone, and heat (Q2) is added to said second reaction zone to promote the decomposition of ammonium carbamate into urea and water, where the liquid phase in at least one of said first reaction zone and second reaction zone is kept in a stirred condition.
N-(4-Substituted-benzoyl)-N′-(β-d-glucopyranosyl)ureas as inhibitors of glycogen phosphorylase: Synthesis and evaluation by kinetic, crystallographic, and molecular modelling methods
Nagy, Veronika,Felfoeldi, Nora,Konya, Balint,Praly, Jean-Pierre,Docsa, Tibor,Gergely, Pal,Chrysina, Evangelia D.,Tiraidis, Costas,Kosmopoulou, Magda N.,Alexacou, Kyra-Melinda,Konstantakaki, Maria,Leonidas, Demetres D.,Zographos, Spyros E.,Oikonomakos, Nikos G.,Kozmon, Stanislav,Tvaroska, Igor,Somsak, Laszlo
supporting information; experimental part, p. 1801 - 1816 (2012/04/10)
N-(4-Substituted-benzoyl)-N′-(β-d-glucopyranosyl) ureas (substituents: Me, Ph, Cl, OH, OMe, NO2, NH2, COOH, and COOMe) were synthesised by ZnCl2 catalysed acylation of O-peracetylated β-d-glucopyranosyl urea as well as in reactions of O-peracetylated or O-unprotected glucopyranosylamines and acyl-isocyanates. O-deprotections were carried out by base or acid catalysed transesterifications where necessary. Kinetic studies revealed that most of these compounds were low micromolar inhibitors of rabbit muscle glycogen phosphorylase b (RMGPb). The best inhibitor was the 4-methylbenzoyl compound (Ki = 2.3 μM). Crystallographic analyses of complexes of several of the compounds with RMGPb showed that the analogues exploited, together with water molecules, the available space at the β-pocket subsite and induced a more extended shift of the 280s loop compared to RMGPb in complex with the unsubstituted benzoyl urea. The results suggest the key role of the water molecules in ligand binding and structure-based ligand design. Molecular docking study of selected inhibitors was done to show the ability of the binding affinity prediction. The binding affinity of the highest scored docked poses was calculated and correlated with experimentally measured Ki values. Results show that correlation is high with the R-squared (R2) coefficient over 0.9.
5′-Uridyl derivatives of N-glycosyl allophanic acid and biuret
Tóth, Marietta,Somsák, László
experimental part, p. 163 - 167 (2011/02/26)
(2′,3′-O-Isopropylidene-5′-uridyl) 4-(2,3,4,6-tetra-O-acetyl-β-d-glycopyranosyl)allophanates were obtained in the reactions of 2′,3′-O-isopropylidene-uridine and O-peracetylated β-d-gluco-, galacto- and xylopyranosylamines, and OCNCOCl. 2,3,4,6-Tetra-O-acetyl-β-d-glucopyranosyl isocyanate and N-(2′,3′-O-isopropylidene-5′-uridyl)urea gave 1-(2,3,4,6-tetra-O-acetyl-β-d-glucopyranosyl)-5-(2′,3′-O-isopropylidene-5′-uridyl)biuret. Deprotection of the β-d-gluco configured allophanate and biuret was carried out by standard methods.
