Microwave Enhanced Acetylation of Alcohols

2002 ◽  
Vol 2002 (6) ◽  
pp. 301-302 ◽  
Author(s):  
Ramesh Patnam ◽  
Fang-Rong Chang ◽  
Reen-Yen Kuo ◽  
Wen-Bin Pan ◽  
Yang-Chang Wu
Keyword(s):  
Acetic Anhydride ◽  
Microwave Irradiation ◽  
Catalytic Amount ◽  
Excellent Yield

Microwave irradiation of alcohols with acetic anhydride in the presence of a catalytic amount of NaOH for a few minutes yielded the corresponding acetylated products in excellent yield.

scholarly journals A Selective Catalytic Method of Enol-acetylation under Microwave Irradiation

1999 ◽  
Vol 23 (6) ◽  
pp. 404-405
Author(s):  
Dipok J. Kalita ◽  
Ruli Borah ◽  
Jadab C. Sarma
Keyword(s):  
Acetic Anhydride ◽  
Microwave Irradiation ◽  
Good Yield ◽  
Catalytic Amount ◽  
Cyclic Ketones ◽  
Catalytic Method ◽  
Enol Acetates

Six-membered cyclic ketones on treatment with acetic anhydride and a catalytic amount of iodine under microwave irradiation give the corresponding enol acetates in good yield.

Microwave Irradiated Acetylation of p-Anisidine: A Step towards Green Chemistry

2008 ◽  
Vol 6 (1) ◽  
Author(s):  
Mousumi Chakraborty ◽  
Vaishali Umrigar ◽  
Parimal A. Parikh
Keyword(s):  
Acetic Acid ◽  
Reaction Time ◽  
Green Chemistry ◽  
Acetic Anhydride ◽  
Microwave Irradiation ◽  
Organic Solvent ◽  
Reaction Times ◽  
Microwave Energy ◽  
Operating Parameters ◽  
Feed Composition

The present study aims at assessing the effect of microwave irradiation against thermal heat on the production of N-acetyl-p-anisidine by acetylation of p-anisidine. The acetylation of p-anisidine under microwave irradiation produces N-acetyl-p-anisidine in shorter reaction times, which offers a benefit to the laboratories as well as industries. It also eliminates the use of excess solvent. Effects of operating parameters such as reaction time, feed composition, and microwave energy and reaction temperature on selectivity to the desired product have been investigated. The results indicate as high as a 98% conversion of N-acetyl-p-anisidine can be achieved within 12-15 minutes using acetic acid. The use of acetic acid as an acetylating agent against conventionally used acetic anhydride eliminates the handling of explosive acetic anhydride and also the energy intensive distillation step for separation of acetic acid. Organic solvent like acetic anhydride are not only hazardous to the environment, they are also expensive and flammable.

scholarly journals Mild and efficient cyanuric chloride catalyzed Pictet–Spengler reaction

2013 ◽  
Vol 9 ◽  
pp. 1235-1242 ◽  
Author(s):  
Ashish Sharma ◽  
Mrityunjay Singh ◽  
Nitya Nand Rai ◽  
Devesh Sawant
Keyword(s):  
Catalytic Amount ◽  
Nitrogen Atmosphere ◽  
Cyanuric Chloride ◽  
Distinct Advantage ◽  
First Report ◽  
Excellent Yield

A practical, mild and efficient protocol for the Pictet–Spengler reaction catalyzed by cyanuric chloride (trichloro-1,3,5-triazine, TCT) is described. The 6-endo cyclization of tryptophan/tryptamine and modified Pictet–Spengler substrates with both electron-withdrawing and electron-donating aldehydes was carried out by using a catalytic amount of TCT (10 mol %) in DMSO under a nitrogen atmosphere. TCT catalyzed the Pictet–Spengler reaction involving electron-donating aldehydes in excellent yield. Thus, it has a distinct advantage over the existing methodologies where electron-donating aldehydes failed to undergo 6-endo cyclization. Our methodology provided broad substrate scope and diversity. This is indeed the first report of the use of TCT as a catalyst for the Pictet–Spengler reaction.

scholarly journals A Convenient Metal-Free Synthesis of (E)-3-Styrylisocoumarins through Annulation of (E)-1,4-Diarylenynes

Synthesis ◽  
2016 ◽  
Vol 48 (19) ◽  
pp. 3382-3392 ◽  
Author(s):  
Guangkuan Zhao ◽  
Ling-Zhi Yuan ◽  
Mylène Roudier ◽  
Jean-François Peyrat ◽  
Abdallah Hamze ◽  
...  
Keyword(s):  
Microwave Irradiation ◽  
Catalytic Amount ◽  
Metal Free ◽  
Toluenesulfonic Acid

A metal-free procedure for the cyclization of (E)-1,4-di­arylenynes is described. The reaction is promoted by a catalytic amount of p-toluenesulfonic acid and takes place in ethanol at 160 °C under microwave irradiation to afford stereoselectively (E)-3-styrylisocoumarins in good to excellent yields.

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.

Neat reaction microwave technology for the synthesis of N-substituted-1,4-dihydropyridines

2004 ◽  
Vol 82 (3) ◽  
pp. 427-429 ◽  
Author(s):  
Mazaahir Kidwai ◽  
Richa Mohan
Keyword(s):  
Microwave Irradiation ◽  
Good Yield ◽  
Solid Support ◽  
Environmentally Benign ◽  
Heating Effect ◽  
Uniform Heating ◽  
Hantzsch Synthesis ◽  
Microwave Technology ◽  
Rate Enhancement ◽  
Excellent Yield

Hantzsch synthesis of N-substituted-1,4-dihydropyridines (1,4-DHP) was carried out using an environmentally benign procedure. Neat reactants were subjected to microwave irradiation (MWI) to give the required products in excellent yield. Appreciable results were not obtained when conventional synthesis using neat reactants was carried out. The good yield and rate enhancement observed in the case of microwave irradiation is attributed to the uniform heating effect of microwaves.Key words: 1,4-dihydropyridines (1,4-DHP), microwave irradiation (MWI), neat reaction, solid support.

scholarly journals LiHSO4/SiO2as a New, Efficient and Reusable Catalytic System for the Chemoselective Conversion of Aldehydes to Acylals under Solvent-Free Conditions

2009 ◽  
Vol 6 (s1) ◽  
pp. S390-S396 ◽  
Author(s):  
Abdolkarim Zare ◽  
Alireza Hasaninejad ◽  
Esmael Rostami ◽  
Ahmad Reza Moosavi-Zare ◽  
Maria Merajoddin ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Acetic Anhydride ◽  
Catalytic System ◽  
Catalytic Amount ◽  
Significant Loss ◽  
Solvent Free ◽  
Reaction Conditions ◽  
Highly Efficient ◽  
Solvent Free Conditions

A highly efficient, green and expeditious solvent-free method is described for the chemoselective conversion of aldehydes to the corresponding acylals in excellent yields, using acetic anhydride in the presence of catalytic amount (20 mol%) of silica-supported LiHSO4. Ketones does not react under these reaction conditions. LiHSO4/SiO2can be recovered and reused without any significant loss of its catalytic activity.

scholarly journals Friedel-Crafts acetylation of indole, 5-methoxyindole and 5-chloroindole using copper triflate under microwave irradiation

2016 ◽  
Vol 19 (4) ◽  
pp. 177-184
Author(s):  
Hai Truong Nguyen ◽  
Phuong Hoang Tran
Keyword(s):  
Catalytic Activity ◽  
Acetic Anhydride ◽  
Microwave Irradiation ◽  
Organic Synthesis ◽  
Significant Loss ◽  
Indole Derivatives ◽  
Efficient Catalyst ◽  
Acidic Catalyst ◽  
Mild Conditions

Friedel-Crafts acetylation is an important reaction in organic synthesis processes. Acetylation of indole derivatives with acetic anhydride as acylating reagent using Cu(OTf)2 as a catalyst has been investigated under microwave irradiation. Different from traditional Lewis acidic catalyst, Cu(OTf)2 was found to be an efficient catalyst for Friedel-Crafts acetylation of indoles under mild conditions. Moreover, Cu(OTf)2 was safe-to-handle, recovered and reused several times without significant loss of catalytic activity.

Lithium Perchlorate and Lithium Bromide Catalysed Solvent Free One Pot Rapid Synthesis of 3-Carboxycoumarins under Microwave Irradiation

2002 ◽  
Vol 2002 (1) ◽  
pp. 40-41 ◽  
Author(s):  
B.P. Bandgar ◽  
L.S. Uppalla ◽  
V.S. Sadavarte
Keyword(s):  
Microwave Irradiation ◽  
Lithium Bromide ◽  
Lithium Perchlorate ◽  
Catalytic Amount ◽  
Solvent Free ◽  
Meldrum's Acid ◽  
Meldrum’S Acid ◽  
Rapid Synthesis ◽  
One Pot ◽  
Substituted Benzaldehydes

Reaction of 2-hydroxy or 2-methoxy substituted benzaldehydes or acetophenones with Meldrum's acid in the presence of a catalytic amount of LiClO4 or LiBr without solvent under microwave irradiation afforded 3-carboxycoumarins in excellent yields.

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