ChemInform Abstract: Solvent Free Highly Dispersed Zinc Oxide within Confined Space of Al-Containing SBA-15 as an Efficient Catalyst for Knoevenagel Condensation.

ChemInform ◽  
2014 ◽  
Vol 45 (41) ◽  
pp. no-no
Author(s):  
Hesamaldin Mahmoudi ◽  
Reihaneh Malakooti
Keyword(s):  
Zinc Oxide ◽  
Knoevenagel Condensation ◽  
Solvent Free ◽  
Confined Space ◽  
Efficient Catalyst ◽  
Highly Dispersed

Highly active zinc oxide-supported lithium oxide catalyst for solvent-free Knoevenagel condensation

2021 ◽  
Vol 133 (3) ◽  
Author(s):  
Prasad Sunkara ◽  
Keshavulu Masula ◽  
Veerasomaiah Puppala ◽  
Yadagiri Bhongiri ◽  
Vijay Kumar Pasala ◽  
...  
Keyword(s):  
Zinc Oxide ◽  
Oxide Catalyst ◽  
Knoevenagel Condensation ◽  
Solvent Free ◽  
Lithium Oxide ◽  
Highly Active

scholarly journals L-Tyrosine as an Eco-Friendly and Efficient Catalyst for Knoevenagel Condensation of Arylaldehydes with Meldrum’s Acid in Solvent-Free Condition under Grindstone Method

2012 ◽  
Vol 2012 ◽  
pp. 1-4 ◽  
Author(s):  
G. Thirupathi ◽  
M. Venkatanarayana ◽  
P. K. Dubey ◽  
Y. Bharathi Kumari
Keyword(s):  
Room Temperature ◽  
Knoevenagel Condensation ◽  
Solvent Free ◽  
Meldrum's Acid ◽  
Meldrum’S Acid ◽  
Efficient Catalyst ◽  
Free Condition ◽  
Solvent Free Condition ◽  
Active Methylene ◽  
Methylene Group

We investigate L-Tyrosine as an efficient catalyst for the Knoevenagel condensation of arylaldehydes with meldrum’s acid containing cyclic active methylene group in solvent-free condition under grindstone method at room temperature to produce substituted-5-benzylidene-2,2-dimethyl-[1,3]dioxane-4,6-diones 3(a–j).

Preparation and Characterization of a Novel Room Temperature Dicationic Ionic Liquid and its Application in the Synthesis of Xanthenediones Under Solvent-Free Conditions

2018 ◽  
Vol 21 (8) ◽  
pp. 602-608 ◽  
Author(s):  
Zainab Ehsani-Nasab ◽  
Ali Ezabadi
Keyword(s):  
Ionic Liquid ◽  
Room Temperature ◽  
Reaction Times ◽  
Significant Loss ◽  
Solvent Free ◽  
Acidity Function ◽  
Efficient Catalyst ◽  
Solvent Free Conditions ◽  
Hammett Acidity Function ◽  
Dicationic Ionic Liquid

Aim and Objective: In the present work, 1, 1’-sulfinyldiethylammonium bis (hydrogen sulfate) as a novel room temperature dicationic ionic liquid was synthesized and used as a catalyst for xanthenediones synthesis. Material and Method: The dicationic ionic liquid has been synthesized using ethylamine and thionyl chloride as precursors. Then, by the reaction of [(EtNH2)2SO]Cl2 with H2SO4, [(EtNH2)2SO][HSO4]2 was prepared and after that, it was characterized by FT-IR, 1H NMR, 13C NMR as well as Hammett acidity function. This dicationic ionic liquid was used as a catalyst for the synthesis of xanthenediones via condensation of structurally diverse aldehydes and dimedone under solvent-free conditions. The progress of the reaction was monitored by thin layer chromatography (ethyl acetate/n-hexane = 3/7). Results: An efficient solvent-free method for the synthesis of xanthenediones has been developed in the presence of [(EtNH2)2SO][HSO4]2 as a powerful catalyst with high to excellent yields, and short reaction times. Additionally, recycling studies have demonstrated that the dicationic ionic liquid can be readily recovered and reused at least four times without significant loss of its catalytic activity. Conclusion: This new dicationic ionic liquid can act as a highly efficient catalyst for xanthenediones synthesis under solvent-free conditions.

Synthesis of Dihydropyrimidinones (DHPMs) and Hexahydro Xanthene Catalyzed by 1,4-Diazabicyclo [2.2.2] Octane Triflate Under Solvent-Free Condition

2019 ◽  
Vol 16 (5) ◽  
pp. 776-786 ◽  
Author(s):  
Deepa ◽  
Geeta D. Yadav ◽  
Mohd J. Aalam ◽  
Pooja Chaudhary ◽  
Surendra Singh
Keyword(s):  
Ethyl Acetoacetate ◽  
Biginelli Reaction ◽  
Solvent Free ◽  
Efficient Catalyst ◽  
Solvent Free Condition ◽  
Solvent Free Conditions ◽  
Xanthene Derivatives ◽  
Different Temperatures ◽  
Flash Column Chromatography ◽  
Biginelli Condensation

Objective:DABCO salts were evaluated as catalysts for the Biginelli reaction between 4- methoxybenzaldehyde, urea and ethyl acetoacetate under solvent-free conditions. 1,4-Diazabicyclo [2.2.2] octane triflate was found to be a simple, inexpensive, highly efficient catalyst for Biginelli reaction for a variety aromatic aldehyde with urea and ethyl acetoacetate at 80°C afforded corresponding 3,4-dihydropyrimidinones in 50-99% yields after 30-120 minutes. 1,3-Cyclohexadione was used in place of ethyl acetoacetate in the absence of urea this methodology is giving hexahydro xanthene derivatives in good to excellent yields after 3-4 hours.Methods:DABCO salt 4 (5 mol%), 4-methoxybenzaldehyde (0.73 mmol) and urea (0.73 mmol) were stirred for 10 minutes at 80°C, then ethyl acetoacetate (1.5 equiv.) was added and reaction mixture was stirred at 80°C for specified time. The resulting solution was stirred continuously and progress of the reaction was followed by TLC. The crude reaction mixture was purified by flash column chromatography on silica gel (hexane/ethyl acetate (1:2)) to give pure desired product.Results:Reaction conditions of the Biginelli reaction were optimized using 4-methoxybenzaldehyde (0.73 mmol), urea (0.73 mmol), and ethyl acetoacetate (5 equiv.) as model substrates catalyzed by 1,4-Diazabicyclo [2.2.2] octane triflate (5 mol%) in a different solvents, screening of different catalysts and different temperatures. Neat condition was found to be the best for the Biginelli condensation and corresponding 3,4- dihydropyrimidinones was obtained in good to excellent yields. When the reaction was carried out with benzaldehyde derivatives and cyclohexane-1,3-dione in place of ethyl acetoacetate in the absence of urea, solely corresponding hexahydro xanthene derivatives were obtained in 61-91% yields.Conclusion:In conclusion, we have applied salts of 1,4-Diaza-bicyclo [2.2.2] octane as catalysts in the Biginelli condensation and corresponding 3,4-dihydropyrimidinones were obtained in 50- 99% yields under solvent free conditions. This methodology is having advantages like simple work-up; low loading of catalyst and reaction was performed at moderate temperature under solvent-free conditions.

Temperature Dependent Green Synthesis of 3-Carboxycoumarins and 3,4-unsubstituted Coumarins

2019 ◽  
Vol 16 (1) ◽  
pp. 130-135 ◽  
Author(s):  
Jack van Schijndel ◽  
Dennis Molendijk ◽  
Luiz Alberto Canalle ◽  
Erik Theodorus Rump ◽  
Jan Meuldijk
Keyword(s):  
Knoevenagel Condensation ◽  
Ammonium Bicarbonate ◽  
Solvent Free ◽  
Temperature Dependent ◽  
Step Procedure ◽  
Synthetic Routes ◽  
High Yields ◽  
Temperature Optima ◽  
Solvent Free Synthesis ◽  
Full Conversion

Aim and Objective: Because of the low abundance of 3,4-unsubstituted coumarins in plants combined with the complex purification process required, synthetic routes towards 3,4-unsubstituted coumarins are especially valuable. In the present work, we explore the possibilities of a solvent-free Green Knoevenagel condensation on various 2-hydroxybenzaldehyde derivatives and malonic acid without the use of toxic organocatalysts like pyridine and piperidine but only use ammonium bicarbonate as the catalyst. Materials and Methods: To investigate the scope of the Green Knoevenagel condensation for the synthesis of 3,4-unsubstituted coumarins, various 2-hydroxybenzaldehyde derivatives were screened as starting material in the optimized two-step procedure developed for 2-hydroxybenzaldehyde. </P><P> Results: This study shows that the intramolecular esterification and the decarboxylation are in competition, but show different temperature optima. In order to suppress premature decarboxylation and maximize the yield of coumarin, a two-step procedure was adopted. The reaction mixture containing ammonium bicarbonate is initially kept at 90ºC for 1 hour. After completion of the cyclization, the temperature of the reaction mixture is increased to 140ºC for 2 hours. Following this protocol, coumarin could be isolated with a yield of 95%. Conclusion: A two-step procedure for the solvent-free synthesis of several 3,4-unsubstituted coumarins was developed using ammonium bicarbonate, resulting in high yields of the desired products. Moreover, this procedure has a low E-factor and is, therefore an environmental friendly reaction in line with the principles of Green Chemistry. It was shown that by initially capping the temperature at 90ºC, premature decarboxylation can be suppressed. After full conversion to the intermediate 3-carboxycoumarin, the temperature can be increased to 140ºC finalizing the reaction. Ammonium bicarbonate was shown to catalyze both the Green Knoevenagel condensation and the decarboxylation step.

Basic Alumina as an Efficient Catalyst for Preparation of Semicarbazones in Solvent Free Conditions

2007 ◽  
Vol 54 (5) ◽  
pp. 1337-1339 ◽  
Author(s):  
Ali Reza Kiasat ◽  
Foad Kazemi ◽  
Mehdi Fallah Mehrjardi
Keyword(s):  
Solvent Free ◽  
Efficient Catalyst ◽  
Basic Alumina ◽  
Solvent Free Conditions
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