2589-21-1Relevant articles and documents
Synthesis of ureas in the bio-alternative solvent Cyrene
Mistry, Liam,Mapesa, Kopano,Bousfield, Thomas W.,Camp, Jason E.
supporting information, p. 2123 - 2128 (2017/07/24)
Cyrene as a bio-alternative solvent: a highly efficient, waste minimizing protocol for the synthesis of ureas from isocyanates and secondary amines in the bio-available solvent Cyrene is reported. This method eliminated the use of toxic solvents, such as
Synthesis of unsymmetrical phenylurea derivatives via oxidative cross coupling of aryl formamides with amines under metal-free conditions
Reddy, Nagireddy Veera,Kumar, Pailla Santhosh,Reddy, Peddi Sudhir,Kantam, Mannepalli Lakshmi,Reddy, Kallu Rajender
, p. 805 - 809 (2015/02/19)
A new synthetic approach for phenylurea derivatives involving the cross coupling of N-aryl formamides with amines through the formation of isocyanate intermediates in the presence of hypervalent iodine reagents is described.
Spectroscopic kinetic study of the interaction of urethanes with amines
Dzalmukhanova,Lodygina,Komratova,Badamshina
, p. 656 - 661 (2014/01/23)
The exchange reactions of phenyl-N-phenylurethane with amines varying in structure and nature have been investigated in o-dichlorobenzene. In the absence of a catalyst and proton-donating compound, the unimolecular decomposition of phenyl-N-phenylurethane into isocyanate and alcohol takes place at a noticeable rate starting at 250°C. The exchange reactions at 60-80°C proceed as a direct exchange between the urethane and the proton donor and are second-order up to high conversions, practically until the disappearance of the entire urethane. The activation energies and apparent rate constants of the exchange reactions of phenyl-N-phenylurethane with various amines have been determined. The results have been explained in terms of the dependence of kinetic parameters of the reaction on the amine nature, structure, and nucleophilicity, on the steric accessibility of the amino group, and on the molecular organization of the solution. Pleiades Publishing, Ltd., 2013.
Accelerating effects of N-aryl-N′,N′-dialkyl ureas on epoxy-dicyandiamide curing system
Liu, Xiang Dong,Kimura, Mika,Sudo, Atsushi,Endo, Takeshi
experimental part, p. 5298 - 5305 (2011/06/21)
This report focuses on epoxy-dicyandiamide (DICY) curing system accelerated by N-aryl-N′,N′-dialkyl urea, aiming at clarifying the accelerating mechanism and the relationship between accelerating effect and molecular structure of the accelerators. Nine N-aryl-N′,N′-dialkyl ureas were synthesized and investigated with measurements of differential scanning calorimetry, thermo gravimetric/differential thermal analysis and NMR spectroscopy. The results revealed that the ureas released the corresponding secondary amines by the thermal dissociation in the presence of epoxide, which led to the formation of tertiary amines that catalyze the addition reaction of DICY to epoxide. Moreover, a tendency that the ureas able to release more compact amines exhibited higher acceleration effects was discovered.
Synthesis of unsymmetrical ureas by sulfur-assisted carbonylation with carbon monoxide and oxidation with molecular oxygen under mild conditions
Mizuno, Takumi,Nakai, Takeo,Mihara, Masatoshi
experimental part, p. 2492 - 2496 (2009/12/08)
With ambient pressure of carbon monoxide and oxygen at room temperature, N,N-dialkyl-N′-arylureas were selectively accessible from secondary amines, aromatic amines, and sulfur in good to excellent yields. For example, N-butyl-N-methyl-N′-(3,4-dichlorophenyl)urea, which is used as a herbicide (neburon), was afforded successfully from butylmethylamine (2 equiv), 3,4-dichloroaniline (1 equiv) and sulfur (1 equiv) in 79% (21.8 g) yield using carbon monoxide (0.1 MPa) and oxygen (0.1 MPa) at 20°C in DMF. Georg Thieme Verlag Stuttgart.
Efficient synthesis of ureas by direct palladium-catalyzed oxidative carbonylation of amines
Gabriele, Bartolo,Salerno, Giuseppe,Mancuso, Raffaella,Costa, Mirco
, p. 4741 - 4750 (2007/10/03)
A general synthesis of symmetrically disubstituted ureas and trisubstituted ureas by direct Pd-catalyzed oxidative carbonylation of primary amines or of a mixture of a primary and a secondary amine, respectively, with unprecedented catalytic efficiencies for this kind of process, is reported. Reactions are carried out at 90-100 °C in DME as the solvent in the presence of PdI 2 in conjunction with an excess of KI as the catalytic system and under 20 atm of a 4:1 mixture of CO and air. In some cases, working in the presence of an excess of CO2 (40 atm) in addition to CO and air (60 atm total) had a beneficial effect on substrate reactivity and product yield. Cyclic five-membered and six-membered ureas were easily formed from primary diamines. The methodology has been successfully applied to the synthesis of pharmacologically active ureas, such as those deriving from α-amino esters or urea NPY5RA-972, a potent antagonist of the neuropeptide Y5 receptor.
Phenylureas. Part 1. Mechanism of the basic hydrolysis of phenylureas
Laudien,Mitzner
, p. 2226 - 2229 (2007/10/03)
The mechanism of the hydrolytic decomposition of phenylureas in basic media in the pH range 12 to 14 is investigated. In this pH range a levelling of the rate-pH curve is observed as well as a change of the substituent influence on the hydrolysis rate. These experimental findings suggest the formation of an unreactive side product of the phenylurea in a parasitic side equilibrium at sufficiently high pH. The urea dissociates at the aryl-NH group to give its conjugate base. For the hydrolytic decomposition of phenylureas an addition-elimination mechanism is proposed as has been established for the alkaline hydrolysis of carboxylic acid esters and amides.
Synthesis of aromatic urea herbicides by the selenium-assisted carbonylation using carbon monoxide with sulfur
Mizuno, Takumi,Kino, Takanobu,Takatoshi, Ito,Miyata, Toshiyuki
, p. 1675 - 1688 (2007/10/03)
Commercially useful aromatic urea herbicides were synthesized in good yields from lithium amides of aromatic amines with thiocarbamates, which were prepared by the selenium-assisted carbonylation of secondary amines with carbon monoxide and sulfur under mild conditions.
Electrochemically controlled hydrogen bonding. O-quinones as simple redox-dependent receptors for arylureas
Ge,Miller,Ouimet,Smith
, p. 8831 - 8838 (2007/10/03)
9,10-Phenanthrenequinone and acenaphthenequinone are shown to act as simple redox-dependent receptors toward aromatic ureas in CH2Cl2 and DMF. Reduction of the o-quinones to their radical anions greatly increases the strength of hydr
