Zinc oxide as the precursor of homogenous catalyst for synthesis of dialkyl carbonate from urea and alcohols

Zhao, Wenbo; Peng, Weicai; Wang, Dengfeng; Zhao, Ning; Li, Junping; Xiao, Fang; Wei, Wei; Sun, Yuhan

doi:10.1016/j.catcom.2008.11.018

Cited by 77 publications

(45 citation statements)

References 14 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, Table 1 indicates that the differences in the performance among those heterogeneous and homogeneous catalysts examined are not large, and so there is still room to further examine the performance of those solid catalysts. and methanol to produce dimethyl carbonate and showed that ZnO was converted to a zinc complex of (NH 3 ) 2 Zn(NCO) 2 , in which two molecules of ammonia were weakly coordinated to Zn atom [32]. This Zn complex was proposed to be the active species for the dimethyl carbonate synthesis from methanol and urea.…”

Section: Resultsmentioning

confidence: 99%

“…These results and those obtained by FTIR led us to propose reaction mechanisms as depicted in Scheme 2. ZnO reacts with isocyanic acid produced from urea, transforming to a zinc complex 1 to which two ammonia molecules are weakly coordinated [32]. One of the coordinated ammonia molecules would be exchanged with one glycerol molecule, resulting in the formation of a complex 2 to which the glycerol molecule interacts with the Zn center through its oxygen atom.…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Synthesis of glycerol carbonate from glycerol and urea using zinc-containing solid catalysts: A homogeneous reaction

Fujita

Yamanishi

Arai

2013

Journal of Catalysis

101

View full text Add to dashboard Cite

Zinc-containing solid catalysts (zinc oxide, smectite, hydrotalcite) and several inorganic zinc salts were used to produce glycerol carbonate from glycerol and urea under solvent-free conditions at 130 ºC and at a reduced pressure of 3 kPa. The leaching of Zn species was observed to occur for the solid catalysts and the carbonate yield was shown to be correlated with the amount of zinc species dissolved into the liquid phase with a single relationship in common for all the catalysts employed. The reaction was also indicated to continue in the liquid phase alone after the solid catalysts were removed from the reaction mixtures by filtration. The results obtained reveal that the reaction takes place homogeneously in the liquid phase irrespective of the parent solid catalysts used. Possible structure of active Zn species was discussed from the results of reaction runs under different conditions and Fourier transform infrared spectroscopy measurements of the liquid phase after the reaction.

show abstract

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Synthesis of glycerol carbonate from glycerol and urea using zinc-containing solid catalysts: A homogeneous reaction

Fujita

Yamanishi

Arai

2013

Journal of Catalysis

101

View full text Add to dashboard Cite

show abstract

“…13 C NMR spectroscopy could provide a good indication of the location of the unsaturation, which was presented by Knothe et al for similar long-chain compounds. [20] Until a distance of eleven carbon atoms with regard to the end of the chain, the carbon atoms of the unsaturation appear at two different shifts, and the difference between these shifts decreases obeying a law of order three for unsubstituted octadecenoic acids.…”

mentioning

confidence: 82%

“…The dis- solution of Zn has also been reported by Zhao et al in a similar medium that consisted of urea and alcohol at 180 8C in an autoclave; a hypothetical mechanism is provided with a catalytically active form that consists of a Zn 2+ cation coordinated by two NH 3 and two NCO ligands. [13] In the nitrilation batch setup, the species present are NH 3 , ammonium carboxylate, water, hydroxyl, amide, and nitrile, the temperature is significantly higher (250-300 8C) and no solvent is used. Then, if a homogeneous catalytically active form is to be created, it may be coordinated with NH 3 and the most nucleophilic molecules (carboxylate or hydroxyl groups).…”

Section: Catalyzed Nitrilationmentioning

confidence: 99%

Ammoniation–Dehydration of Fatty Acids into Nitriles: Heterogeneous or Homogeneous Catalysis?

et al. 2013

View full text Add to dashboard Cite

EAU:ENERGIE+AMB:SBE:AAUFatty nitriles have lately become of interest in the framework of biofuels and for the valorization of the oil part of biomass to form fine chemicals or polymers. The production of long-chain fatty nitriles by the direct reaction of acids with NH3 has not been extensively studied, although several catalysts have been developed and published as patents. The characterization of this reaction with and without catalyst is, to the best of our knowledge, performed for the first time in this study. Several catalysts with various acid-base features were tested, and the best catalysts at 250 degrees C (Zn- and In-based catalysts) were further studied. Catalytically active forms and models are proposed for the Zn- and In-based catalysts, and the kinetic parameters for the amide to nitrile reaction are evaluated

show abstract

“…As depicted in Scheme 3, the thermal decomposition of urea produces ammonia and isocyanic acid molecules. The reaction of isocyanic acid with an alcohol molecule and SnCl 2 may give an tin(II) intermediate, where both alcohol and isocyanic acid are weakly coordinated to the tin chloride [33].…”

Section: Mechanistic Insightsmentioning

confidence: 99%

Tin-Catalyzed Urea Alcoholysis With β-Citronellol: A Simple and Selective Synthesis of Carbamates

Chaves

Silva

2016

Catal Lett

View full text Add to dashboard Cite

Tin(II) chloride is a stable and water tolerant Lewis acid, commercially available and less corrosive than Brønsted acid catalysts. Our proposal was demonstrated that SnCl 2 was an efficient catalyst on the urea alcoholysis with b-citronellol. We investigated the effects of main reaction parameters such as concentration and tin(II) catalyst nature, reagents stoichiometry and reaction temperature. In homogenous conditions with DMSO as solvent, the SnCl 2 -catalyzed urea alcoholysis reactions under air flux achieved high conversion and selectivity for b-citronellyl carbamate (ca. 90 and 95 %, respectively). Among tin(II) catalysts assessed, SnCl 2 was more active due to its total solubility. Possible intermediates of active Sn(II) species were discussed based on the results of catalytic runs and FT-IR spectroscopy measurements of the liquid phase after the reaction. FT-IR spectroscopy data showed that the active species could be a complex of a Sn(II) atom coordinated with N=C=O. This novel and phosgene-free selective process provide an inexpensive and attractive route to synthesize terpenic carbamates through inexpensive and renewable reactant (i.e. urea). Moreover, SnCl 2 was also an efficient catalyst on synthesis of b-citronellyl carbonate. Graphical AbstractOH -citronellol H 2 N NH 2 O Urea + SnCl 2 DMSO Air flow O NH 2 O -citronellyl Carbamate NH 3 + Ammonia β 0 3 0 6 0 9 0 0 20 40 60 80 100 (%) Time (min) β -Citronellol Conversion Selectivity β-Citronellyl Carbamate β

show abstract

Zinc oxide as the precursor of homogenous catalyst for synthesis of dialkyl carbonate from urea and alcohols

Cited by 77 publications

References 14 publications

Synthesis of glycerol carbonate from glycerol and urea using zinc-containing solid catalysts: A homogeneous reaction

Synthesis of glycerol carbonate from glycerol and urea using zinc-containing solid catalysts: A homogeneous reaction

Ammoniation–Dehydration of Fatty Acids into Nitriles: Heterogeneous or Homogeneous Catalysis?

Tin-Catalyzed Urea Alcoholysis With β-Citronellol: A Simple and Selective Synthesis of Carbamates

Contact Info

Product

Resources

About