632-22-4Relevant academic research and scientific papers
A rhodium peroxido complex in Mono-, Di-, and peroxygenation reactions
Meier, Gregor,Braun, Thomas
, p. 3280 - 3284 (2011)
A versatile peroxido complex: The rhodium peroxido complex 1, which can be prepared from 2 and dioxygen, participates in mono-oxygenation of a phosphine and dioxygenation of tetrakis(dimethylamino)ethylene to give, respectively, phosphine oxide and a urea derivative, while peroxygenation of 9,10-dimethylanthracene to yield the anthracene endoperoxide takes place in the presence of dioxygen and substoichiometric amounts of 1 (see scheme). Copyright
Studies of reaction of tetramethylthiourea with hydrogen peroxide: evidence of formation of tetramethylthiourea monoxide as a key intermediate of the reaction
Dereven’kov, Ilia A.,Ivlev, Pavel A.,Salnikov, Denis S.,Bischin, Cristina,Attia, Amr A. A.,Silaghi-Dumitrescu, Radu,Makarov, Sergei V.
, p. 496 - 509 (2017)
The reaction between tetramethylthiourea (TMTU) and hydrogen peroxide was studied by UV–VIS spectroscopy, ESI mass spectrometry, 1H NMR, cyclic voltammetry and surface-enhanced Raman scattering. We found that the reaction includes two consecutive steps, that is, (i) an oxidation of TMTU to TMTU monoxide (TMTMO) and (ii) further oxidation of TMTU monoxide to tetramethylurea (TMU) and sulfate. The second step is complex and seems to include extrusion of sulfur monoxide (SO). Density functional theory calculations were employed on tetramethylthiourea oxide models in order to underline differences between monoxide and di- and trioxides. Calculations predict that the TMTMO structure can be best explained as an adduct of thiourea with an oxygen atom (═S–>O).
On the exchange reaction,, using hexafluoroacetone
Gruber, Matthias,Schmutzler, Reinhard
, p. 99 - 105 (1990)
The reaction of λ3-phospha-diazetidin-thione, 1 with hexafluoroacetone (HFA) furnished not only the expected addition product, the λ5P-perfluoropinacolyl phosphorane, 2. In addition, HFA was observed to cause {A figure is presented} exchange in 2, and exclusive formation of a urea derivative, 3, was noted upon prolonged interaction of HFA with 2. Likewise, N,N,N′,N′,-tetramethylthiourea, 1, was found to be converted to N,N,N′,N′-tetrarmethylurea, 5, by HFA. The reactions were followed by 1H-, 13C-, 19F- and 31P-n.m.r. spectroscopy.
Copper(II) chloride-catalyzed oxidative carbonylation of glycerol to glycerol carbonate
Casiello, Michele,Monopoli, Antonio,Cotugno, Pietro,Milella, Antonella,Dell'Anna, Maria Michela,Ciminale, Francesco,Nacci, Angelo
, p. 99 - 106 (2014)
A systematic study on copper(II) as catalyst for the synthesis of glycerol carbonate via oxidative carbonylation is here reported for the first time. Copper(II) chloride has been found to efficiently promote the process under homogeneous conditions treating glycerol with CO:O2 (Ptot = 4 MPa; P(O2) = 0.7 MPa), in DMA at 130 C and in the presence of pyridine as co-catalyst. Excellent conversions (>92%) and selectivities (>93%) are obtained in relatively short reaction times (3-4 h) also with copper(II) complexes. The catalyst overall TON is evaluated and new experimental evidences are provided allowing significant advancements in the mechanism comprehension.
Amine-Responsive Disassembly of AuI–CuI Double Salts for Oxidative Carbonylation
Cao, Yanwei,Yang, Jian-Gong,Deng, Yi,Wang, Shengchun,Liu, Qi,Shen, Chaoren,Lu, Wei,Che, Chi-Ming,Chen, Yong,He, Lin
supporting information, p. 2080 - 2084 (2019/12/24)
A sensitive amine-responsive disassembly of self-assembled AuI-CuI double salts was observed and its utilization for the synergistic catalysis was enlightened. Investigation of the disassembly of [Au(NHC)2][CuI2] revealed the contribution of Cu-assisted ligand exchange of N-heterocyclic carbene (NHC) by amine in [Au(NHC)2]+ and the capacity of [CuI2]? on the oxidative step. By integrating the implicative information coded in the responsive behavior and inherent catalytic functions of d10 metal complexes, a catalyst for the oxidative carbonylation of amines was developed. The advantages of this method were clearly reflected on mild reaction conditions and the significantly expanded scope (51 examples); both primary and steric secondary amines can be employed as substrates. The cooperative reactivity from Au and Cu centers, as an indispensable prerequisite for the excellent catalytic performance, was validated in the synthesis of (un)symmetric ureas and carbamates.
Tetramethylurea and preparation method thereof
-
Paragraph 0052-0054; 0057; 0058; 006; 0062; 0065; 0066, (2018/10/19)
The invention provides tetramethylurea and a preparation method thereof. The preparation method comprises the following steps that S1, dimethylamine and triphosgene are provided; S2, the dimethylamineand the triphosgene react to generate the tetramethylurea. According to the preparation method of the tetramethylurea, the dimethylamine and the triphosgene are used as raw materials, the dimethylamine can be a dimethylamine water solution or dimethylamine gas, and the triphosgene can be triphosgene itself or an organic triphosgene solution. The preparation method is simple in operation, high inproduct yield, low in cost and suitable for industrial production.
Reactions of Secondary Amines with Dichlorocarbene Generated in Aqueous–Alkaline Medium in the Presence of N-Methylmorpholine N-Oxide
Hasratyan,Bagdasaryan,Hayotsyan,Attaryan
, p. 959 - 960 (2018/07/31)
Dichlorocarbene generated from chloroform in aqueous–alkaline medium in the presence of N-methylmorpholine N-oxide is converted to phosgene which reacts in situ with secondary amines to afford tetrasubstituted ureas.
Metal-free direct thiocarbamation of imidazopyridines with carbamoyl chloride and elemental sulfur
Deng, Jian-Chao,Zhuang, Shi-Bin,Liu, Quan-Zhu,Lin, Zi-Wei,Su, Yu-Liang,Chen, Jia-Hao,Tang, Ri-Yuan
, p. 54013 - 54016 (2017/12/06)
The combination of elemental sulfur and carbamoyl chloride was found to act as a carbamothioyl group surrogate for direct thiocarbamation of imidazopyridines in the absence of a metal catalyst.
Highly efficient one-pot assembly of peptides by double chemoselective coupling
Sampaio-Dias, Ivo E.,Sousa, Carlos A. D.,Silva-Reis, Sara C.,Ribeiro, Sara,García-Mera, Xerardo,Rodríguez-Borges, José E.
supporting information, p. 7533 - 7542 (2017/09/27)
This study describes a methodological advancement in solution-phase peptide synthesis via the development of a convenient and operational protocol to synthesize oligopeptides in a one-pot three-step cascade method, in which two peptide bonds are introduced chemoselectively. Tri- to hexapeptides were obtained in high global yields (80-95%) with virtually no epimerization as determined via HPLC. The methodology described herein represents a faster, easier and milder approach to the synthesis of peptides, and it operates at equimolar amounts. This protocol comprises the formation of secondary and tertiary amides and is compatible with Z, Boc and Fmoc N-protecting groups as well as the use of d/l and non-proteinogenic amino acids.
The nonenzymatic decomposition of guanidines and amidines
Lewis, Charles A.,Wolfenden, Richard
supporting information, p. 130 - 136 (2014/01/23)
To establish the rates and mechanisms of decomposition of guanidine and amidine derivatives in aqueous solution and the rate enhancements produced by the corresponding enzymes, we examined their rates of reaction at elevated temperatures and used the Arrhenius equation to extrapolate the results to room temperature. The similar reactivities of methylguanidine and 1,1,3,3-tetramethylguanidine and their negative entropies of activation imply that their decomposition proceeds by hydrolysis rather than elimination. The influence of changing pH on the rate of decomposition is consistent with attack by hydroxide ion on the methylguanidinium ion (k2 = 5 × 10 -6 M-1 s-1 at 25 C) or with the kinetically equivalent attack by water on uncharged methylguanidine. At 25 C and pH 7, N-methylguanidine is several orders of magnitude more stable than acetamidine, urea, or acetamide. Under the same conditions, the enzymes arginase and agmatinase accelerate substrate hydrolysis 4 × 1014-fold and 6 × 1012-fold, respectively, by mechanisms that appear to involve metal-mediated water attack. Arginine deiminase accelerates substrate hydrolysis 6 × 1012-fold by a mechanism that (in contrast to the mechanisms employed by arginase and agmatinase) is believed to involve attack by an active-site cysteine residue.
