1219-99-4Relevant articles and documents
-
Bognar et al.
, p. 255 (1953)
-
Catalytic conversions of isocyanate to urea and glucose to levulinate esters over mesoporous α-Ti(HPO4)2·H2O in green media
Hazra Chowdhury, Arpita,Hazra Chowdhury, Ipsita,Biswas, Surajit,Chakrabortty, Pekham,Islam, Sk. Manirul
, p. 16452 - 16460 (2020)
We have described a facile solvothermal synthesis of a sheet-like α-Ti(HPO4)2·H2O nanomaterial. The material comprises 10.7 nm nanoparticles along with ordered mesopores throughout its hexagonal building blocks. The material possesses a bandgap of 3.86 eV and works as an efficient catalyst for the selective synthesis of ureas from a broad range of isocyanates in the presence of H2O at room temperature with a high product yield (up to 93%) and a TOF value up to 15.25 h-1. The α-Ti(HPO4)2·H2O nanomaterial also catalytically converts glucose to levulinic acid (LA) and subsequently LA to alkyl levulinates in the presence of different alcohols with a high product yield (up to 98%) and a TOF value up to 43.00 h-1. Furthermore, all the reactions are performed under green and facile catalytic conditions without using any hazardous solvent. The α-Ti(HPO4)2·H2O catalyst material was also found to be reusable for manifold cycles for all the reactions, keeping its catalytic efficiency along with its structural and morphological characteristics unaffected, supporting its industrial relevance.
Palladium-Catalyzed Aerobic Oxidative Carbonylation of Amines Enables the Synthesis of Unsymmetrical N,N′-Disubstituted Ureas
Zeng, Honglan,Du, Hongyan,Gong, Xu,Zhang, Jie,Han, Wei
, p. 1223 - 1226 (2021/06/02)
A ligand-free palladium-catalyzed aerobic oxidative carbonylation of amines for the synthesis of ureas, particular unsymmetrically N,N′-disubstituted ureas, which cannot be accessed by any other palladium-catalyzed oxidative carbonylation of amines to date, is presented. An array of symmetrical and unsymmetrical ureas were straightforwardly synthesized by using inexpensive, readily available, stable, and safe amines with good to excellent yields under a pressure of 1 atm. This novel method employs oxygen as the sole oxidant and offers an attractive alternative to transition-metal-based oxidant systems.
Di-tert-butyl peroxide (DTBP)-mediated synthesis of symmetrical N,N′-disubstituted urea/thiourea motifs from isothiocyanates in water
Chen, Ling,Dong, Yibo,Wu, Yangjie,Yang, Jinchen,Zhang, Jinli
supporting information, (2021/12/01)
ABATRACT: A direct approach to N,N′-disubstituted urea/thiourea from the self-condensation reactions of isothiocyanates in water has been developed. This access tolerated a wide range of functional groups on the aromatic ring, providing a practical and environment-friendly process to N,N′-disubstituted urea/thiourea in moderate to excellent yields from safe and easily available starting materials. A plausible mechanism of the desulfurization self-condensation reaction for urea was also proposed and the role of di-tert-butyl peroxide (DTBP) and copper catalyst in the present strategy was demonstrated with the help of ESI mass spectrometry of intermediate studies.
Investigation of active sites using solid state 27Al and 31P MAS NMR in ceramic amorphous aluminophosphate materials prepared from different potassium salts of phosphate for the synthesis of diphenyl urea derivatives
Harish,Kathyayini,Baby, Bindhu,Nagaraju
, (2021/04/19)
Ceramic amorphous aluminophosphate (CAmAlP) catalysts were prepared by precipitation method using different phosphate salts of potassium such as KH2PO4, K4P2O7 and K2HPO4 as well as H3PO4. The prepared materials were characterized by PXRD, FT-IR, XPS, SEM, BET Surface area, NH3-TPD, 27Al NMR and 31P NMR analytical methods. The catalytic activity of the materials was checked in the synthesis of diphenyl urea (DPU) from aniline and diethyl carbonate, under refluxing conditions. Further, the general application of the catalysts was tested using various substituted anilines. The recyclability of the catalysts was also studied. Uncertainties in percentage yields were calculated to check the reproducible surface properties. The P-XRD, BET Surface area and NH3-TPD results indicated that the materials were amorphous with mesoporous texture, surface areas and acidities in the range 200–260 m2/g and 0.4–0.7 mmol/g respectively. 27Al NMR studies revealed that Al is present in three different coordination states such as tetrahedral, pentagonal and octahedral. The relative percentages of these Al sites depends on the type of the potassium precursor phosphate salt used. Both tetrahedral and pentagonal Al sites in conjunction with each other represented catalytically active sites. An increase in the pentagonal sites contributed to additional increments to the catalytic activity of CAmAlP. The catalyst prepared from KH2PO4 was found to be the best and demonstrated 96% DPU yield.
