The effect of cosolvent cyclohexane, chloroform, and acetonitrile on the keto-enol tautomeric equilibrium of ethyl acetoacetate in supercritical CO2 was studied by UV-Vis spectroscopy over the pressure range from 76 t...The effect of cosolvent cyclohexane, chloroform, and acetonitrile on the keto-enol tautomeric equilibrium of ethyl acetoacetate in supercritical CO2 was studied by UV-Vis spectroscopy over the pressure range from 76 to 110 bar at 308.15 K. It was found that the equilibrium constant decreases with increasing polarity of the cosolvents.展开更多
The enol contents and equilibrium constants for keto-enol tautomerism of ethyl acetoacetate in supercritical (SC) CO2 with and without cosolvent ethanol and in various liquid solvents were investigated by UV spectrosc...The enol contents and equilibrium constants for keto-enol tautomerism of ethyl acetoacetate in supercritical (SC) CO2 with and without cosolvent ethanol and in various liquid solvents were investigated by UV spectroscopy. The local dielectric constant about the solute in SC CO2/ethanol system was obtained through the correlation between Gibbs free energy of tautomerism and Onsager-Kirkwood solvent quantity. The great difference between local dielectric constant and that calculated from homogeneous dielectric medium theory suggests clustering of the cosolvent around the solute.展开更多
The enol form of ethyl acetoacetate(EAA)displays interesting spectroscopic characteristics;this form of ethyl acetylacetate is very important in condensation reaction.In this investigation,we have studied the interact...The enol form of ethyl acetoacetate(EAA)displays interesting spectroscopic characteristics;this form of ethyl acetylacetate is very important in condensation reaction.In this investigation,we have studied the interactions and the complex formation constants(K_(f))with nano alumina(10–20 nm)particle and alumina(mesh 135)compounds as Lewis acids in the acetonitrile solvent using absorption spectroscopy and related calculations.Furthermore,in this study we calculated the thermodynamic parameters of this reaction.The trend of reactivity of the ethyl acetoacetate(EAA)complexes toward the above Lewis acids,based on the solvent as follows:nano alumina compound>alumina compound.展开更多
A series of 1,4-dihydropyridines have been prepared by a one-pot condensation of aldehydes,ethyl acetoacetate,and ammonium acetate in the presence of a heterogeneous catalyst silica sulfuric acid at room temperature u...A series of 1,4-dihydropyridines have been prepared by a one-pot condensation of aldehydes,ethyl acetoacetate,and ammonium acetate in the presence of a heterogeneous catalyst silica sulfuric acid at room temperature under solvent-free condition. This new protocol has the advantage of short reaction time and excellent yields,and is an environmentally benign route to the synthesis of 1,4-dihydropyridines.展开更多
An operationally simple and inexpensive catalyst system was developed for the cross coupling of aryl iodides and bromides with ethyl acetoacetate by using CuI as catalyst and Nmethyl glycine as ligand. The reaction re...An operationally simple and inexpensive catalyst system was developed for the cross coupling of aryl iodides and bromides with ethyl acetoacetate by using CuI as catalyst and Nmethyl glycine as ligand. The reaction represents a novel Cu-catalyzed C-C cross coupling reaction. This procedure is applicable to the preparation of pharmaceutically important α- arylalkanoic acids.展开更多
The acetoacetyl group can be used to improve superabsorbent resins since it is more active than the hydroxyethyl group. The acetoacetyl group can be introduced into the side group of hydroxyethyl cellulose (HEC) to a...The acetoacetyl group can be used to improve superabsorbent resins since it is more active than the hydroxyethyl group. The acetoacetyl group can be introduced into the side group of hydroxyethyl cellulose (HEC) to activate HEC using the ester exchange reaction between HEC and ethyl acetoacetate (EAA) to improve HEC grafting. This paper discusses the main factors affecting the reaction, such as the amount of EAA and catalyzer, the reaction temperature, and the reaction time. The acetoacetyl group was successfully introduced into HEC. Within specified ranges, increasing the amount of EAA, the reaction temperature and the reaction time will increase the acetoacetylation.展开更多
An efficient,catalyst-free and eco-friendly ultrasound-assisted novel one-pot pseudo-five-component synthesis of aryl-bis-[1H-pyrazol-5-ol-4yl]methanes,het(aryl)-bis-[1H-pyrazol-5-ol-4yl]methanes and their 1-phenyl de...An efficient,catalyst-free and eco-friendly ultrasound-assisted novel one-pot pseudo-five-component synthesis of aryl-bis-[1H-pyrazol-5-ol-4yl]methanes,het(aryl)-bis-[1H-pyrazol-5-ol-4yl]methanes and their 1-phenyl derivatives in water is reported.The products were obtained in excellent yield in shorter duration with high purity,by simple filtration.This synthetic methodology has been optimized and discussed herein.展开更多
基金This work was financially support by National Basic Research Project(G2000048010).
文摘The effect of cosolvent cyclohexane, chloroform, and acetonitrile on the keto-enol tautomeric equilibrium of ethyl acetoacetate in supercritical CO2 was studied by UV-Vis spectroscopy over the pressure range from 76 to 110 bar at 308.15 K. It was found that the equilibrium constant decreases with increasing polarity of the cosolvents.
文摘The enol contents and equilibrium constants for keto-enol tautomerism of ethyl acetoacetate in supercritical (SC) CO2 with and without cosolvent ethanol and in various liquid solvents were investigated by UV spectroscopy. The local dielectric constant about the solute in SC CO2/ethanol system was obtained through the correlation between Gibbs free energy of tautomerism and Onsager-Kirkwood solvent quantity. The great difference between local dielectric constant and that calculated from homogeneous dielectric medium theory suggests clustering of the cosolvent around the solute.
文摘The enol form of ethyl acetoacetate(EAA)displays interesting spectroscopic characteristics;this form of ethyl acetylacetate is very important in condensation reaction.In this investigation,we have studied the interactions and the complex formation constants(K_(f))with nano alumina(10–20 nm)particle and alumina(mesh 135)compounds as Lewis acids in the acetonitrile solvent using absorption spectroscopy and related calculations.Furthermore,in this study we calculated the thermodynamic parameters of this reaction.The trend of reactivity of the ethyl acetoacetate(EAA)complexes toward the above Lewis acids,based on the solvent as follows:nano alumina compound>alumina compound.
文摘A series of 1,4-dihydropyridines have been prepared by a one-pot condensation of aldehydes,ethyl acetoacetate,and ammonium acetate in the presence of a heterogeneous catalyst silica sulfuric acid at room temperature under solvent-free condition. This new protocol has the advantage of short reaction time and excellent yields,and is an environmentally benign route to the synthesis of 1,4-dihydropyridines.
文摘An operationally simple and inexpensive catalyst system was developed for the cross coupling of aryl iodides and bromides with ethyl acetoacetate by using CuI as catalyst and Nmethyl glycine as ligand. The reaction represents a novel Cu-catalyzed C-C cross coupling reaction. This procedure is applicable to the preparation of pharmaceutically important α- arylalkanoic acids.
文摘The acetoacetyl group can be used to improve superabsorbent resins since it is more active than the hydroxyethyl group. The acetoacetyl group can be introduced into the side group of hydroxyethyl cellulose (HEC) to activate HEC using the ester exchange reaction between HEC and ethyl acetoacetate (EAA) to improve HEC grafting. This paper discusses the main factors affecting the reaction, such as the amount of EAA and catalyzer, the reaction temperature, and the reaction time. The acetoacetyl group was successfully introduced into HEC. Within specified ranges, increasing the amount of EAA, the reaction temperature and the reaction time will increase the acetoacetylation.
基金Dr.Mohamed Afzal Pasha acknowledges the University Grants Commission(UGC),New Delhi,INDIA for the BSR Faculty Fellowship(No.F.18–1/2011(BSR),November 2019).
文摘An efficient,catalyst-free and eco-friendly ultrasound-assisted novel one-pot pseudo-five-component synthesis of aryl-bis-[1H-pyrazol-5-ol-4yl]methanes,het(aryl)-bis-[1H-pyrazol-5-ol-4yl]methanes and their 1-phenyl derivatives in water is reported.The products were obtained in excellent yield in shorter duration with high purity,by simple filtration.This synthetic methodology has been optimized and discussed herein.
