scholarly journals Oxidation of Cyclohexanol and Cyclohexanone by Monochromate Ions in Organic Solvents and on Solvent Free Microwave Irradiation under Phase Transfer Catalysis - A Comparative Study

2021 ◽  
Vol 33 (9) ◽  
pp. 2033-2037
Author(s):  
P. Bashpa ◽  
P. Rajendran ◽  
K. Bijudas
Keyword(s):  
Microwave Irradiation ◽  
Organic Phase ◽  
Phase Transfer Catalysis ◽  
Phase Transfer ◽  
Mineral Acid ◽  
Solvent Free ◽  
High Yield ◽  
Catalysis Condition ◽  
Solvent Free Condition ◽  
Spectral Technique

Oxidation of cyclohexanol and cyclohexanone were carried out by acidified monochromate ions in ethyl acetate and toluene under phase transfer catalysis and also in solvent free condition under microwave irradiation. The extraction of monochromate ions from aqueous medium to organic phase was carried by employing various phase transfer catalysts in the presence of mineral acids. The effect of [catalyst] and [mineral acid] on extraction of monochromate from aqueous phase to organic phase was also studied. The product obtained, namely adipic acid obtained with both reactants was characterized by its melting point and infrared spectral technique. The reaction was over within 15 min with more than 85% yield at a temperature of 323 K under microwave irradiation where as it gave around 70% yield at 353 K within 150 min under phase transfer catalysis condition. The enhanced reaction rate and high yield of product substantiate the application of phase transfer catalytic technique under microwave irradiation for organic synthesis. A suitable mechanism for the oxidation of substrates by monochromate under phase transfer catalysis is also suggested.

scholarly journals Microwave-Assisted Improved Regioselective Synthesis of 12H-Benzopyrano[3,2-c][1]benzopyran-5-ones by Radical Cyclisation

2011 ◽  
Vol 2011 ◽  
pp. 1-6 ◽  
Author(s):  
Pradipta Kumar Basu ◽  
Amrita Ghosh
Keyword(s):  
Microwave Irradiation ◽  
Phase Transfer Catalysis ◽  
Phase Transfer ◽  
Benzyl Bromide ◽  
Catalytic Amount ◽  
Ammonium Bromide ◽  
Catalysis Condition ◽  
Microwave Assisted ◽  
Tributyltin Hydride ◽  
Tetrabutyl Ammonium

Two new effective methodologies have been adopted for the preparation of 4-(2′-bromobenzyloxy)benzopyran-7-ones 3(a–h). In the first methodology, 4-hydroxy[1]benzopyran-2-ones 1(a–d) was alkylated with 2-bromobenzyl bromide 2a or 2-bromo-5-methoxy benzyl bromide 2b under phase transfer catalysis condition using lithium hydroxide/tetrabutyl ammonium bromide in N,N-dimethylformamide at 40–50°C and in the second method the microwave irradiation protocol has been exploited by simply mixing of 4-hydroxy[1]benzopyran-2-ones 1(a–d) with 25% excess of 2-bromobenzyl bromide 2a or 2-bromo-5-methoxy benzyl bromide 2b. A catalytic amount of TBAB and potassium carbonate were added and irradiated in an open Erlenmeyer flask in a microwave oven for 4–10 min. The tributyltin-hydride-mediated radical cyclisation of 3(a–h) was carried out under microwave irradiation to generate 12H-benzopyrano[3,2-c][1]benzopyran-5-ones 4(a–h) in 78–88% yield and in this technique yields were significantly improved and reaction time was shortened compared to the previously reported conventional radical cyclisation method.

scholarly journals Facile Condensation of Aromatic Aldehydes with Chroman-4-ones and 1-Thiochroman-4-ones Catalysed by Amberlyst-15 under Microwave Irradiation Condition

2011 ◽  
Vol 8 (2) ◽  
pp. 863-869 ◽  
Author(s):  
Tapas K. Mandal ◽  
Rammohan Pal ◽  
Rina Mondal ◽  
Asok K. Mallik
Keyword(s):  
Microwave Irradiation ◽  
Aldol Condensation ◽  
Aromatic Aldehydes ◽  
Solvent Free ◽  
Environmentally Benign ◽  
High Yield ◽  
Irradiation Condition ◽  
Free Condition ◽  
Amberlyst 15 ◽  
Solvent Free Condition

Different aromatic aldehydes and cinnamaldehyde undergo cross-aldol condensation with chroman-4-ones and1-thiochroman-4-ones in the presence of amberlyst-15 under microwave irradiation in solvent free condition to afford rapidly the correspondingE-3-arylidene andE-3-cinnamylidene derivatives, respectively, in high yield. This process is simple, efficient and environmentally benign.

A Rapid and High-yield Synthesis of Aryloxyacetyl Hydrazides under Microwave Irradiation and with Phase Transfer Catalysis

2005 ◽  
Vol 2005 (7) ◽  
pp. 432-433 ◽  
Author(s):  
Tai-Bao Wei ◽  
Hong Liu ◽  
Man-Lin Li ◽  
You-Ming Zhang
Keyword(s):  
Microwave Irradiation ◽  
Efficient Method ◽  
Phase Transfer Catalysis ◽  
Phase Transfer ◽  
High Yield ◽  
Reaction Conditions

A series of aryloxyacetyl hydrazides 4a–l were synthesised under microwave irradiation and phase transfer catalysis conditions. By the optimisation of the reaction conditions, a rapid, high-yield and efficient method for the preparation of aryloxyacetyl hydrazide was given.

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