Green chemistry microwaves

Desai, K. R. (2005). Green Chemistry Microwave Synthesis, Mumbai Himalaya. 

Green chemistry involves design of chemical synthesis to prevent pollution and thereby, solve the environmental problems. The microwave chemistry is a current approach in green chemistry. Microwave-mediated reactions occur more rapidly, safely and in environment-friendly manner with high yields. Such reactions reduce the amount of waste products and increase the pure required products. Thus, one can conclude that microwave-mediated synthesis is a green chemical technology because microwave not only accelerate chemical processes but also improve yield, selectivity, reduces pollution and enable reaction to occur in solvent-free conditions. 

R. S. Varma, PureAppl. Chem. 2001, 73, 193-198 R. S. Varma, Tetrahedron 2002, 58, 1235-1255 R. S. Varma, Advances in Green Chemistry Chemical Syntheses Using Microwave Irradiation, Kavitha Printers, Bangalore, 2002. 

A. Loupy, A. Petit, J. Hamelin, F. Texier-Boullet, P. Jacquault, D. Mathe, Synthesis 1998,1213-1234 R. S. Varma, Green Chem. 1999, 43-55 M. Kidawi, Pure Appl. Chem. 2001, 73, 147-151 R. S. Varma, Pure Appl. Chem. 2001, 73,193-198 R. S. Varma, Tetrahedron 2002, 58,1235-1255 R. S. Varma, Advances in Green Chemistry Chemical Syntheses Using Microwave Irradiation, Kavitha Printers, Bangalore, 2002. 

Most of these publications describe important accelerations of a wide range of organic reactions especially when performed under solvent-free conditions. The combination of solvent-free reaction conditions and microwave irradiation leads to large reductions in reaction times, enhancement of yield, and, sometimes [3, 4] in selectivity with several advantages of an eco-friendly approach, termed green chemistry . 

An efficient solventless synthesis of imidazolones via the Knoevenagel reaction using microwave irradiation has appeared recently in Green Chemistry [76] (Scheme 8.52). 

Cineole derivatives, of interest as potential cosmetic products, were obtained under a green chemistry procedure , i. e. one without solvent, with microwave activation according to Scheme 8.54. 

Ease of separation of tritiated products from a reaction medium is an important feature in the choice of labeling procedure. Sometime ago we used polymer-sup-ported acid and base catalysts [12, 13] to good effect and with the current interest in Green Chemistry one can expect to see more studies where the rate accelerations observed under microwave-enhanced conditions are combined with the use of solid catalysts such as Nafion, or zeolites. 

The first positive results in the synthesis of these heterocyclic compounds by MCR of aminoazoles, aldehydes, and barbituric acids were published in 2008 by Shi et al. [111]. They also used green chemistry methodology and carried out treatment of the starting materials in water under microwave irradiation. The temperature optimization procedure and search for the best catalytic system allowed selecting one equivalent of p-TSA and 140°C as optimum conditions for the synthesis. With application of the procedure elaborated 24 novel pyrazolopyr-idopyrimidines 76 were generated (Scheme 33). 

Strauss, C.R., Application of microwaves for environmentally benign organic chemistry, In Clark, J. and Duncan, M. (Eds.), Handbook of Green Chemistry and Technology, Blackwell Science Oxford, 2002, pp. 397-415. 

Shieh, W.-C. Dell, S. Repic, O. DBU and microwave-accelerated green chemistry in methylation of phenols, indoles, and benzimidazoles with dimethyl carbonate. Org. Lett. 2001, 3, 4279—4281. 

Barbier-Baudry, D. and L. Braachais. Synthesis of Polycarolactone by Microwave Irradiation—An Interesting Route to Synthesize This Polymer by Green Chemistry. Environ Chem Lett 1 (2003) 19-23. 

For microwave-heated reactions under solvent-free conditions, the following major benefits have been claimed, particularly with regard to green chemistry [36] ... 

Varma RS (2002) Advances in green chemistry chemical syntheses using microwave irradiation. Kavitha, Bangalore... 

Gospodinova, N., A. Grelard, M. Jeannin, G.C. Chitanu, A. Carpov, V. Thiery and T. Besson, Efficient Solvent-Free Microwave Phosphorylation of Microcrystalline Cellulose, Green Chemistry, 4, 220-222 (2002). 

Hoogenboom, R. and U.S. Schubert, Microwave-Assisted Cationic Ring-Opening Polymerization of a Soy-Based 2-Oxazoline Monomer, Green Chemistry, 8, 895-899 (2006). 

Niichter, M., B. Ondruschka, W. Bonrathand A. Gum, Microwave Assisted Synthesis - A Critical Technology Overview, Green Chemistry, 6, 128-141 (2004). 

Fraga-Drubreuil, J. and Cherouvrier, J.R. 2000. Clean solvent-free dipolar cycloaddition reactions assisted by focused microwave irradiations for the synthesis of new ethyl 4-cyano-2-oxazoline-4-carboxylates. Green Chemistry, 2 226-29. 

Kumar, H.M.S., Subba Reddy, B.V., Reddy, E.J., and Yadav, J.S. 1999. Microwave-assisted eco-friendly synthesis of 2-alkylated hydroquinones in dry media. Green Chemistry, l-.Ul-Al. 

Ranu, B.C., Guchhait, S.K., Ghosh, K., and Patra, A. 2000. Construction of bicyclo-[2.2.2] octanone systems by microwave-assisted solid phase Michael addition followed by AI2O3-mediated intramolecular aldolisation. An eco-friendly approach. Green Chemistry, 1 5-6. 

A. Rauf and N. N. Farshori, Microwave-Induced Synthesis of Aromatic Heterocycles, SpringerBriefs in Green Chemistry for Sustainability, DOI 10.1007/978-94-007-1485-4 l, The Author(s) 2012... 

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