1848-01-7Relevant academic research and scientific papers
Light-induced synthesis of unsymmetrical organic carbonates from alcohols, methanol and CO2under ambient conditions
Saini, Sandhya,Gour, Nand Kishor,Khan, Shafiur Rehman,Deka, Ramesh Chandra,Jain, Suman L.
supporting information, p. 12800 - 12803 (2021/12/13)
The present work describes the first visible light-assisted, metal-free and organic base 1,1,3,3-tetramethyl guanidine (TMG) mediated synthesis of unsymmetrical methyl aryl/alkyl carbonates from the reaction of alcohols, methanol, and CO2 in high to excel
Non-symmetrical dialkyl carbonate synthesis promoted by 1-(3-trimethoxysilylpropyl)-3-methylimidazolium chloride
Kumar, Subodh,Jain, Suman L.
supporting information, p. 3057 - 3061 (2013/10/01)
An efficient synthesis of non-symmetrical dialkyl carbonates promoted by 1-(3-trimethoxysilylpropyl)-3-methylimidazolium chloride ionic liquid as a reaction medium is described. The ionic liquid can easily be recovered and reused several times without sig
C,N-chelated organotin(IV) compounds as catalysts for transesterification and derivatization of dialkyl carbonates
Weidlich, Tomas,Dusek, Libor,Vystrcilova, Barbora,Eisner, Ales,Svec, Petr,Ruzicka, Ales
, p. 293 - 300 (2012/10/07)
The potential catalytic activity of selected C,N-chelated organotin(IV) compounds (e.g. halides and trifluoroacetates) for derivatization of both dimethyl carbonate (DMC) and diethyl carbonate (DEC) was investigated. Some tri-, di- and monoorganotin(IV) species (LCN(n-Bu)2SnCl (1), LCN(n-Bu)2SnCl.HCl (1a), LCN(n-Bu) 2SnI (2), LCNPh2SnCl (3), LCNPh 2SnI (4), LCN(n-Bu)SnCl2 (5), L CNSnBr3 (6) and [LCNSn(OC(O)CF 3)]2(μ-O)(μ-OC(O)CF3)2 (7)) bearing the LCN moiety (LCN = 2-(N,N-dimethylaminomethyl) phenyl-) were assessed as catalysts for reactions of both DMC and DEC with various substituted anilines. The catalytic activities of 4 and 7 for derivatization of DMC with p-substituted phenols were studied for comparison with the standard base K2CO3/Silcarbon K835 catalyst (catalyst 8). The composition of resulting reaction mixtures was monitored by multinuclear NMR spectroscopy, GC and GC-MS techniques. In general, catalysts 1, 3 and 7 exhibited the highest catalytic activity for all reactions studied, while some of them yielded selectively carbonates, carbamates, lactam or substituted urea. Copyright
Transesterification of dimethyl carbonate with phenol using Br?nsted and Lewis acidic ionic liquids
Deshmukh, Krishna M.,Qureshi, Ziyauddin S.,Dhake, Kishor P.,Bhanage, Bhalchandra M.
experimental part, p. 207 - 211 (2011/09/12)
Transesterification reaction of dimethyl carbonate with phenol to methylphenyl carbonate and diphenyl carbonate using dibutyltin oxide catalyst in conjunction with Br?nsted and Lewis acidic ionic liquids was studied. It was observed that the use of ionic liquids significantly enhances the yield of diphenyl carbonate. The ionic liquid having p-toluenesulfonate as anion and metal halide (e.g. ZnCl2) as Lewis acid precursor exhibited higher activity and selectivity for diphenyl carbonate formation. Furthermore, the Br?nsted and Lewis acidity of ionic liquids was measured by IR spectroscopy using pyridine as a probe and their Lewis acidity order was also determined.
METHOD OF PREPARING DIALKYLCARBONATES
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Page/Page column 8; 10, (2008/06/13)
The present invention relates to a process of preparing dialkylcarbonates, and particularly to an improved process of preparing dialkylcarbonates, which comprises performing a reaction between an alcohol compound and a chloroformate derivative in the presence of an imidazole compound, thereby enabling to prepare dialkylcarbonates with high yield in a mild condition without using toxic raw materials and to easily separate impurities.
Dimethyl carbonate as an ambident electrophile
Tundo, Pietro,Rossi, Laura,Loris, Alessandro
, p. 2219 - 2224 (2007/10/03)
(Chemical Equation Presented) The features of various anions having different soft/hard character (aliphatic and aromatic amines, alcohoxydes, phenoxides, thiolates) are compared with regard to nucleophilic substitutions on dimethyl carbonate (DMC), using different reaction conditions. Results are well in agreement with the Hard-Soft Acid-Base (HSAB) theory. Accordingly, the high selectivity of monomethylation of CH2 acidic compounds and primary aromatic amines with DMC can be explained by two different subsequent reactions, which are due to the double electrophilic character of DMC. The first step consists of a hard-hard reaction and selectively produces a soft anion, which, in the second phase, selectively transforms into the final monomethylated product, via a soft-soft nucleophilic displacement (yield >99% at complete conversion, using DMC as solvent).
Ketene acetals from thermolysis of aryloxy methoxy oxadiazolines. Evidence for carbonyl ylide intermediates
Couture, Philippe,El-Saidi, Manal,Warkentin, John
, p. 326 - 332 (2007/10/03)
Thermolysis of oxadiazolines (5) in benzene at 110°C leads to ketene acetals (11) as minor products. Carbonyl ylide intermediates (6), and oxiranes (7), presumably in equilibrium with those ylides, are implicated as unstable precursors of the ketene aceta
Nucleophilic substitution reactions of phenyl chloroformates
Yew, Kyoung Han,Koh, Han Joong,Lee, Hai Whang,Lee, Ikchoon
, p. 2263 - 2268 (2007/10/03)
Methanolysis and aminolysis of phenyl chloroformates in acetonitrile have been investigated.The rates are slow due to initial-state stabilization by strong resonance electron donation from the phenoxy group.In both reactions the large positive values of ρY = 0.8-1.6 and low ΔH(excit.) and ΔS(excit.) values show that the transition state is strongly associative with little bond breaking.This mechanism is supported by the relatively large solvent isotope effect, kMeOH/kMeOD = ca. 2.3-2.5, and by the relatively strong inverse secondary kinetic isotope effect, kH/kD =/ca. 0.74-0.94, involving deuteriated aniline nuclephiles, in addition to a negative value of ρXY.The dependence on aniline basicity, βx(βnuc) =/ca. 0.8, and the ρX values of -2.3 are similar to those corresponding values for the reactions of benzoyl chlorides which have been predicted to react by an associative SN2 mechanism.These observations are consistent with a concerted displacement mechanism for the methanolysis and aminolysis of phenyl chloroformates.
