3066-65-7Relevant articles and documents
Visible-light photocatalyzed oxidative decarboxylation of oxamic acids: a green route to urethanes and ureas
Pawar, Govind Goroba,Robert, Frédéric,Grau, Etienne,Cramail, Henri,Landais, Yannick
supporting information, p. 9337 - 9340 (2018/08/31)
A sustainable metal-free route to urethanes and ureas based on a photocatalyzed oxidative decarboxylation of oxamic acids is described. The reaction includes in situ generation of an isocyanate from the oxamic acid, using an organic dye as a photocatalyst, a hypervalent iodine reagent as an oxidant and a light source, which trigger the free-radical decarboxylation. This protocol successfully avoids the isolation, purification and storage of carcinogenic isocyanates and allows elaboration of urethanes and ureas in a one-pot process from commercially available sources.
N-Substituted carbamate synthesis using urea as carbonyl source over TiO2-Cr2O3/SiO2 catalyst
Wang, Peixue,Ma, Yubo,Liu, Shimin,Zhou, Feng,Yang, Benqun,Deng, Youquan
, p. 3964 - 3971 (2015/07/15)
The use of urea as an active form of carbon dioxide is a feasible way to substitute phosgene in the chemical industry. This paper reports an effective route for the synthesis of N-substituted carbamates from amines, urea and alcohols. Under the optimized reaction conditions, several important N-substituted carbamates were successfully synthesized in 95-98% yields over a TiO2-Cr2O3/SiO2 catalyst. The catalyst could be reused for several runs without deactivation. The catalysts were characterized by BET, XPS, XRD, and TPD, which suggested that the strength and amount of the acidic and basic sites might be the major reason for the high catalytic activity of TiO2-Cr2O3/SiO2.
Immobilisation of iron tris(β-diketonates) on a two-dimensional flat amine functionalised silicon wafer: A catalytic study of the formation of urethane, from ethanol and a diisocyanate derivative
Conradie,Conradie,Erasmus
, p. 52 - 59 (2014/06/10)
A series of immobilised iron tris(β-diketonato) catalysts on a Si-wafer was prepared, by covalently anchoring the Fe(β-diketonato) 3 complexes [where β-diketonato = (RCOCHCOR′)-, with 1 = acac (R = CH3; R′ = CH3), 2 = dbm (R = C6H5; R′ = C6H5), 3 = tfaa (R = CH3; R′ = CF3), and 4 = hfaa (R = CF3; R′ = CF3)], onto an aminated functionalised Si-wafer. These new catalysts were characterised by X-ray photo-electron spectroscopy (XPS) and atomic force microscopy (AFM). XPS data revealed that ca. 27-91% of all the amine groups anchored the catalyst, Fe(β-diketonato)3. Different Gaussian peaks could be fitted into the F 1s peak, due to the fluorine either being positioned adjacent to the -C-O-Fe-, or to the -C-N-Fe-. The binding energy of the Fe 2p3/2 peak varied between ca. 710.4 and 711.0 eV, depending on the electron donating properties of the R-groups on the β-diketonato ligands, expressed as the sum of the Gordy group electronegativities of the R-groups in the β-diketonato ligands. The AFM photographs showed that the surface changed dramatically after each treatment: after amination (binding of the aminate silane onto the hydroxylate Si-wafer) the Si-wafer turned from flat with a few spikes, to a very wavy surface with smooth lumps. The surface topography again changed, after covalent anchoring of the iron tris(β-diketonato) complexes, to a nodular surface with poorly defined grain boundaries. These immobilised iron tris(β-diketonato) on Si-wafer catalysts, were evaluated for their catalytic activity, during the formation of hexamethylenediurethane from hexamethylenediisocyanate and ethanol. The TOF varied between 15 and 46 s-1, depending on the electron donating properties of the R-groups on the β-diketonato ligands. The more electron donating the R groups, the higher the TOF.
METHOD FOR PRODUCING CARBAMATE COMPOUND
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Page/Page column 15, (2011/06/24)
A task of the present invention is to provide a process for preparation a carbamate compound using a carbonic acid ester and an amide compound in the presence of a basic compound(s), wherein the process is a novel industrial method which is advantageous in that the reaction rate is faster than conventional and the by-produced ester compound can be recovered, and the present invention is directed to a method comprising reacting an amide compound represented by the formula (1) with a carbonic acid ester represented by the formula (2) in the presence of a basic compound(s) to obtain a carbamate compound represented by the formula (3).
N-substituted carbamates syntheses with alkyl carbamates as carbonyl source over Ni-promoted Fe3O4 catalyst
Shang, Jianpeng,Guo, Xiaoguang,Shi, Feng,Ma, Yubo,Zhou, Feng,Deng, Youquan
scheme or table, p. 328 - 336 (2011/05/14)
A series of catalysts of magnetic iron oxide containing Ni with different nickel content were prepared with co-precipitation method and tested in the syntheses of N-substituted carbamates from various amines and alkyl carbamates. Under the optimized reaction conditions, various N-substituted carbamates were successfully synthesized with 90-98% isolated yield. The catalyst could be recovered based on the magnetic property of the catalyst and reused for five runs without deactivation. The catalysts were characterized with X-ray photoelectron spectroscopy, X-ray diffraction, temperature-programmed reduction, temperature-programmed desorption, and Moessbauer spectroscopy analyses. The results showed that the catalytic activity may be derived from the delicate synergy between Ni and Fe species resulted in specific basic sites. Quasi in situ FT-IR and isotopic tracer revealed that the formation of substituted urea was the key step and the N-substituted carbamate was formed via further alcoholysis of the substituted urea.
Carbon Dioxide as a Phosgene Replacement: Synthesis and Mechanistic Studies of Urethanes from Amines, CO2, and Alkyl Chlorides
McGhee, William,Riley, Dennis,Christ, Kevin,Pan, Yi,Parnas, Barry
, p. 2820 - 2830 (2007/10/02)
Several carbamate esters were synthesized from amines, carbon dioxide, and alkyl chlorides.The effect of added base on the yield and selectivity of carbamate ester formation was found to be highly important with the use of sterically hindered guanidine bases giving the best results.Relative rate studies were carried out giving the following order of reactivity between carbamate anions in acetonitrile with benzyl chloride giving carbamate esters: Et2NCO2(-) = Bu2NCO2(-) > t-BuNHCO2(-) = CyNHCO2(-) = s-BuNHCO2(-) > PhNHCO2(-) > CyCH2NHCO2(-) = n-octylNHCO2(-) = n-BuNHCO2(-).Rate studies were carried out with the diethyl, s-butyl, phenyl, and n-butyl carbamates and activation parameters were determined to be Et2NCO2(-), ΔH(excit.) = 11.8 kcal/mol, ΔS(excit.) = -33 eu; s-BuNHCO2(-), ΔH(excit.) = 12.8 kcal/mol, ΔS(excit.) = -33 eu; PhNHCO2(-), ΔH(excit.) = 14.3 kcal/mol, ΔS(excit.) = -28 eu; n-BuNHCO2(-), ΔH(excit.) = 23.4 kcal/mol, ΔS(excit.) = -3 eu.The unusual results obtained from the use of n-BuNHCO2(-) prompted further studies which showed that the rate of the reaction was inversely dependent on carbon dioxide pressure (20 psig CO2, k = 4.84E-4 M-1 s-1; 120 psig CO2, k = 1.83E-4 M-1 s-1).Nitrogen NMR spectroscopy indicated, via a labeling study with 15N amines and 13C enriched carbon dioxide, the formation of doubly inserted product from the addition of two carbon dioxides to ethylamine in acetonitrile.
Process for the preparation of aliphatic di- and polyurethanes
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, (2008/06/13)
A process for the preparation of aliphatic, cycloaliphatic, arylaliphatic and aliphatic-cycloaliphatic di- and polyurethanes wherein primary aliphatic, cycloaliphatic, arylaliphatic or aliphatic-cycloaliphatic di- or polyamines are reacted with urea and a
Process for the preparation of urethanes
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, (2008/06/13)
A process for the preparation of urethanes. Urethanes having the general formula R1 (NHCOOR2)n are reacted with an alcohol at a temperature of 120° to 400° C. in amounts such that, for every mol of the urethane, at least o
A Novel Catalytic Synthesis of Carbamates by Oxidative Alkoxycarbonylation of Amines in the Presence of Palladium and Iodide
Fukuoka, Shinsuke,Chono, Masazumi,Kohno, Masashi
, p. 399 - 400 (2007/10/02)
Palladium and iodide catalyse the oxidative carbonylation of amines by CO, O2, and alcohols to give carbamates in high yields.
