105-58-8Relevant articles and documents
Fabrication of solid strong bases with a molecular-level dispersion of lithium sites and high basic catalytic activity
Sun, Lin-Bing,Shen, Jie,Lu, Feng,Liu, Xiao-Dan,Zhu, Li,Liu, Xiao-Qin
, p. 11299 - 11302 (2014)
New solid strong bases were fabricated at room temperature by grafting lithium-containing molecular precursors onto β-cyclodextrin. The solid bases show strong basicity with a molecular-level dispersion of lithium sites, which are highly active in transesterification reactions and impossible to realize through the traditional high-temperature method. the Partner Organisations 2014.
Magnesium oxide nanosheets as effective catalysts for the synthesis of diethyl carbonate from ethyl carbamate and ethanol
Li, Fengjiao,Li, Huiquan,Wang, Liguo,He, Peng,Cao, Yan
, p. 1021 - 1034 (2015)
A series of MgO catalysts were prepared by thermal decomposition and precipitation methods. Their catalytic performance was evaluated in the synthesis of diethyl carbonate (DEC) from ethyl carbamate (EC) and ethanol. Among them, MgO prepared using sodium carbonate as the precipitant and calcined at 450°C (MgO-SC-450) exhibited much higher catalytic activity. An excellent DEC yield of 58.0% with a high DEC selectivity of 92.1% could be achieved over the MgO-SC-450 catalyst under optimized reaction conditions: 210°C, ethanol/EC molar ratio of 10, and 3 h. Moreover, the catalytic activity could be essentially retained during recycling experiments. The structure and surface basicity of the MgO catalysts were characterized by X-ray diffraction (XRD), Mastersizer 2000, N2 adsorption, field-emission scanning electron microscopy (FE-SEM), and temperature-programmed desorption of CO2 (CO2-TPD). It was found that MgO-SC-450 possessed nanosheet morphology. Furthermore, a larger amount of appropriate medium basic β sites of MgO-SC-450 with the peak located between 225°C and 275°C was favourable for obtaining much superior catalytic activity. Quasi in situ FT-IR experiments were carried out to elucidate the adsorption behaviours of reactants. It was found that EC could be effectively activated and ethanol could be dissociated to a strong nucleophilic ethoxy group by MgO. In addition, theoretical calculation proved the co-adsorption of EC and ethanol on the MgO surface. Based on the results of quasi in situ FT-IR experiments and theoretical calculation, a plausible reaction mechanism has been proposed for the catalytic reaction.
Ambident ethyl N-nitrosocarbamate anion: Experimental and computational studies of alkylation and thermal stability
Benin, Vladimir,Kaszynski, Piotr,Radziszewski, J. George
, p. 14115 - 14126 (2002)
Alkylation of N-nitrosourethane tetrabutylammonium salt (2-Bu4N) with four electrophiles (Mel, Etl, i-Prl, and PhCH2Br) was studied by 1H NMR in CD2Cl2 and CD3CN solutions. The ratio of the three regioisomers N-alkyl-N-nitrosourethane 3, azoxy 4, and O-alkyldiazotate 5 was practically independent of solvent but dependent on the nature of the electrophile. The anion 2 and O-alkyl derivative 5 are thermally unstable and decompose to ethyl carbonates 9 and 10, respectively, with a first-order rate constant (2-Bu4N: k = 18.5 ± 0.1 × 10-5 S-1; 5b (R = Et): k = 1.77 ± 0.02 × 10-5 s-1; 5d (R = PhCH2): k = 4.78 ± 0.08 × 10-5 s-1 at 35 °C in CD2Cl2). Further kinetic measurements gave activation parameters for the decomposition of 2 (Ea = 24.2 ± 0.3 kcal/mol and In A = 30.9 ± 0.1). Gas-phase calculations at the MP2(fc)/6-31+G(d)//MP2(fc)/6-31G(d) level showed that the alkylation of 2 involves the lone electron pairs of the N-N-O atoms, and the calculated activation energies correspond well to the observed ratio of regioisomers 3-5. The theoretical analysis of the decomposition processes supports a concerted mechanism with a four-center transition state in the first step for all four compounds. The calculated activation energy order (2 5 3 4) is consistent with the observed order of stability. Decomposition of 2 and 5 is a unimolecular process, giving carbonates 9 and 10 in a single step. In contrast, rearrangement of 3 and 4 leads to alkyl diazonium ions. A detailed theoretical analysis indicates that the rate-determining step for thermal decomposition of 2 is the loss of molecular nitrogen, while in 5 it is the trans-cis isomerization process. The nonconcerted process involving homolytic cleavage of the O-N bond in 5 was found to be significantly less favorable.
Au (III)/N-containing ligand complex: A novel and efficient catalyst in carbonylation of alkyl nitrite
Li, Jinjin,Hu, Jianglin,Li, Guangxing
, p. 1401 - 1404 (2011)
High catalytic activity of a gold N-containing ligand complex in the homogenous carbonylation of alkyl nitrite to dialkyl carbonate with KI as the promoter is reported. [AuCl2(phen)]Cl/KI (phen = 1,10-phenanthroline) complex has been used as a catalyst in the carbonylation of ethyl nitrite. The use of iodide as a promoter resulted in a significant increase in activity (TOF: 35.8 mol?molAu- 1?h- 1) and selectivity (91.7%) for diethyl carbonate at 3.0 MPa, 80 °C and 5 h. Based on the results of ESI-MS, UV-Vis, and cyclic voltammetry (CV) experiments, a mechanism is proposed for the carbonylation of alkyl nitrite in a homogeneous system using a gold N-containing ligand complex as a catalyst.
Mesostructured graphitic carbon nitride as a new base catalyst for the efficient synthesis of dimethyl carbonate by transesterification
Xu, Jie,Long, Kai-Zhou,Chen, Ting,Xue, Bing,Li, Yong-Xin,Cao, Yong
, p. 3192 - 3199 (2013)
Mesostructured graphitic carbon nitride (CN-MCF) material has been prepared using carbon tetrachloride and ethylenediamine as precursors and mesocellular silica foam as a hard template, and characterized by XRD, N2 adsorption-desorption, TEM, FT-IR, and XPS techniques. The material was employed as a catalyst for the production of dimethyl carbonate (DMC) via transesterification of ethylene carbonate (EC) with methanol (MeOH). The influences of reaction conditions, including time, temperature, and the molar ratios of MeOH to EC, on the catalytic performance have been investigated in detail. Catalytic results revealed that CN-MCF could catalyze the transesterification reaction with high efficiency, affording a high DMC yield of 78% and stable catalytic activity for several running cycles. Furthermore, a possible reaction mechanism for the g-CN-catalyzing transesterification of EC with MeOH has been proposed. The Royal Society of Chemistry.
An effective combination catalyst of CeO2and zeolite for the direct synthesis of diethyl carbonate from CO2and ethanol with 2,2-diethoxypropane as a dehydrating agent
Chang, Tao,Choi, Jun-Chul,Fukaya, Norihisa,Hamura, Satoshi,Matsumoto, Seiji,Mishima, Takayoshi,Nakagawa, Yoshinao,Tamura, Masazumi,Tomishige, Keiichi
, p. 7321 - 7327 (2020)
The combination catalyst of CeO2 and H-FAU zeolite was effective for the direct synthesis of diethyl carbonate from CO2 and ethanol with 2,2-diethoxypropane as a dehydrating regent, where H-FAU catalyzed hydrolysis of 2,2-diethoxypropane. The combination catalyst provided high activity and a high diethyl carbonate yield of 72% based on 2,2-diethoxypropane at a low temperature of 393 K. This journal is
Construction of Polycyclic β-Ketoesters Using a Homoconjugate Addition/Decarboxylative Dieckmann Annulation Strategy
Chen, Zhiwei,Hong, Allen Y.,Linghu, Xin
, p. 6225 - 6234 (2018)
The construction of arene-fused cyclic β-ketoesters from 2-iodoaryl esters and 1,1-cyclopropane diesters is detailed. The synthetic method takes advantage of a CuI·SMe2-mediated homoconjugate addition followed by a decarboxylative Dieckmann cyclization to afford valuable polycyclic building blocks. Various iodoaryl esters and 1,1-cyclopropane diesters were evaluated, and the limitations of both reactions are discussed. Several mechanistic probes are detailed and synthetic applications are described.
Synthesis of ethyl octyl ether from diethyl carbonate and 1-octanol over solid catalysts. A screening study
Guilera,Bringué,Ramírez,Iborra,Tejero
, p. 21 - 29 (2012)
The synthesis of ethyl octyl ether (EOE) from a mixture of diethyl carbonate (DEC) and 1-octanol (1:2 molar ratio) over several solid catalysts was studied in batch mode at 150 °C and 25 bar. Catalyst screening revealed that EOE could be successfully obtained over some acid catalysts. In particular the highest yield was achieved over acid ion-exchange resins (33% after 8 h). A reaction scheme of the process is proposed. Selectivity to EOE was mainly affected by the production of diethyl ether (DEE) and di-n-octyl ether (DNOE). However, EOE was the main ether obtained (60 mol%), followed by DEE (20 mol%) and DNOE (20 mol%). By comparing the behavior of several acid resins, it was seen that the synthesis of EOE was highly related to the structural resin properties. It was found that the accessibility of DEC and 1-octanol to acid centers was improved over highly swollen and low polymer density resins. Thus, gel-type resins with low divinylbenzene content are the most suitable to produce EOE (e.g., Amberlyst 121, Dowex 50Wx2-100 and CT224).
Highly active and reusable ternary oxide catalyst for dialkyl carbonates synthesis
Unnikrishnan,Srinivas
, p. 42 - 49 (2015)
The application of ternary oxides, prepared through calcination of rare-earth modified Mg/Al-hydrotalcite (HT), as highly active, selective, and reusable solid catalysts for dialkyl carbonates synthesis by transesterification reaction is reported. Dimethyl carbonate, for example, was prepared by reacting ethylene carbonate with methanol in 100 mol% selectivity at a yield of 95 mol%. Among several rare-earth modified precursors, La (10 mol%)-HT showed the highest activity. This catalyst was active even at ambient conditions. Basicity of the catalyst played crucial role on its performance. The activity of these catalysts was superior to the hitherto known solid catalysts for this reaction.
Direct condensation reaction of carbon dioxide with alcohols using trisubstituted phosphine-carbon tetrabromide-base system as a condensing agent
Kadokawa, Jun-Ichi,Habu, Hideyuki
, p. 2205 - 2208 (1999)
This paper describes the preparation of carbonates by the direct condensation of CO2 with alcohols using a trisubstituted phosphine-carbon tetrabromide-base system as a condensing agent. The yield of dibenzyl carbonate from CO2 and benzyl alcohol was at most 90.7%. The reaction of CO2 with the other primary alcohols such as methanol, ethanol, butan-1-ol, hexan-1-ol, allyl alcohol, and ethylene glycol also gave corresponding carbonates in relatively high yields, whereas yields of carbonates from CO2 and secondary alcohols were low. Copyright 1999 by the Royal Society of Chemistry.
