Green Chemistry with Microwave Energy

  • Rajender S. Varma


Green chemistry utilizes a set of 12 principles that reduces or eliminates the use or generation of hazardous substances in the design, manufacture, and applications of chemical products [1]. This newer chemical approach protects the environment by inventing safer and eco-friendly chemical processes that prevent pollution “at source” rather than cleaning up “end-of-the-pipe” by-products and pollutants generated by traditional synthesis.


Ionic Liquid Aryl Halide Tetra Butyl Ammonium Bromide Aryl Chloride Volatile Organic Solvent 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


Green chemistry

Green chemistry is the broad discipline that encompasses the design of chemical processes and products that eliminate or reduce the generation and use of hazardous substances. It applies across the life cycle, including the design, manufacture, and use of a chemical product.


Microwaves (0.3–300 GHz) lie in the electromagnetic radiation spectrum between radiowave (Rf) and infrared (IR) frequencies with relatively large wavelengths and are a form of energy and not heat. This nonionizing radiation, incapable of breaking chemical bonds, is a form of energy that manifests itself as heat through interaction with the polar medium.


Literally meaning to “maintain,” “support,” or “endure” the concept of sustainability calls for policies and strategies that meet society’s present needs without compromising the ability of future generations to meet their own needs.



The views expressed in this article are those of the author and do not necessarily reflect the views and policies of the US Environmental Protection Agency. The use of trade names does not imply endorsement by the US Government.


Primary Literature

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    Luque R, Baruwati B, Varma RS (2010) Magnetically separable nanoferrite-anchored glutathione: aqueous homocoupling of arylboronic acids under microwave irradiation. Green Chem 12:1540–1543. doi:10.1039/C0GC00083CGoogle Scholar
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    Polshettiwar V, Varma RS (2008) Ring-fused aminals: catalyst and solvent-free microwave-assisted α-amination of nitrogen heterocycles. Tetrahedron Lett 49:7165–7167Google Scholar
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    Varma RS, Naicker KP, Liesen PJ (1998) Microwave-accelerated crossed Cannizzaro reaction using barium hydroxide under solvent-free conditions. Tetrahedron Lett 3:8437–8440Google Scholar
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    Pillai UR, Sahle-Demessie E, Namboodiri VV, Varma RS (2002) An efficient and ecofriendly oxidation of alkenes using iron nitrate and molecular oxygen. Green Chem 4:495–497Google Scholar
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    Kumar D, Chandra Sekhar KVG, Dhillon H, Rao VS, Varma RS (2004) An expeditious synthesis of 1-aryl-4-methyl-1, 2, 4-triazolo [4, 3-a] quinoxalines under solvent-free conditions using iodobenzene diacetate. Green Chem 6:156–157Google Scholar
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    Kumar D, Sundaree MS, Patel G, Rao VS, Varma RS (2006) Solvent-free facile synthesis of novel α-tosyloxy β-keto sulfones using [hydroxy(tosyloxy)iodo] benzene. Tetrahedron Lett 47:8239–8241Google Scholar
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    Varma RS (2008) Chemical activation by mechanochemical mixing, microwave, and ultrasonic irradiation. Green Chem 10:1129–1130Google Scholar
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    Polshettiwar V, Varma RS (2007) Tandem bis-aza-Michael addition reaction of amines in aqueous medium promoted by polystyrenesulfonic acid. Tetrahedron Lett 48:8735–8738Google Scholar
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    Kumar D, Reddy VB, Mishra BG, Rana RK, Nadagouda MN, Varma RS (2007) Nanosized magnesium oxide as catalyst for the rapid and green synthesis of substituted 2-amino-2-chromenes. Tetrahedron 63:3093–3097Google Scholar
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    Skouta R, Varma RS, Li CJ (2005) Efficient Trost’s γ-addition catalyzed by reusable polymer-supported triphenylphosphine in aqueous media. Green Chem 7:571–575Google Scholar
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    Ju Y, Kumar D, Varma RS (2006) Revisiting nucleophilic substitution reactions: microwave-assisted synthesis of azides, thiocyanates, and sulfones in an aqueous medium. J Org Chem 71:6697–6700Google Scholar
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    Namboodiri VV, Varma RS (2001) Microwave-accelerated Suzuki cross-coupling reaction in polyethylene glycol (PEG). Green Chem 3:146–148Google Scholar
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    Kumar D, Patel G, Mishra BG, Varma RS (2008) Ecofriendly polyethylene glycol (PEG)-promoted Michael addition reactions of α, β-unsaturated compounds. Tetrahedron Lett 49:6974–6976Google Scholar
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    Keh CCK, Namboodiri VV, Varma RS, Li C-J (2002) Direct formation of tetrahydropyranols via catalysis in ionic liquid. Tetrahedron Lett 43:4993–4996Google Scholar
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    Li Z, Wei C, Varma RS, Li C-J (2004) Three-component coupling of aldehyde, alkyne, and amine catalyzed by silver in ionic liquid. Tetrahedron Lett 45:2443–2446Google Scholar
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    Yang X-F, Wang M, Varma RS, Li C-J (2003) Aldol- and Mannich-type reactions via in situ olefin migration in ionic liquid. Org Lett 5:657–660Google Scholar
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    Yang X-F, Wang M, Varma RS, Li C-J (2004) Ruthenium-catalyzed tandem olefin migration aldol and Mannich-type reactions in ionic liquid. J Mol Catal A Chem 214:147–154Google Scholar
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    Yoo K, Namboodiri VV, Varma RS, Smirniotis PG (2004) Ionic liquid-catalyzed alkylation of isobutane with 2-butene. J Catal 222:511–519Google Scholar
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    Namboodiri VV, Varma RS, Sahle-Demessie E, Pillai UR (2002) Selective oxidation of styrene to acetophenone in the presence of ionic liquids. Green Chem 4:170–173Google Scholar
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    Nadagouda MN, Hoag GE, Collins JB, Varma RS (2009) Green synthesis of Au nanostructures at room temperature using biodegradable plant surfactants. Cryst Growth Des 9:4979–4983Google Scholar
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    Nadagouda MN, Castle A, Murdock RC, Hussain SM, Varma RS (2010) In vitro biocompatibility of nanoscale zerovalent iron particles (nZVI) synthesized using tea polyphenols. Green Chem 12:114–122Google Scholar
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    Moulton MC, Braydich-Stolle LK, Nadagouda MN, Kunzelman S, Hussain SM, Varma RS (2010) Synthesis, characterization and biocompatibility of “green” synthesized silver nanoparticles using tea polyphenols. Nanoscale 2:763–770Google Scholar
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    Hoag GE, Collins JB, Holcomb JL, Hoag JR, Nadagouda MN, Varma RS (2009) Degradation of bromothymol blue by ‘greener’ nano-scale zerovalent iron synthesized using tea polyphenols. J Mater Chem 19:8671–8677Google Scholar
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    Virkutyte J, Varma RS (2010) Fabrication and visible-light photocatalytic activity of novel Ag/TiO2−xNx photocatalyst. New J Chem 34:1094–1096Google Scholar
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    Virkutyte J, Baruwati B, Varma RS (2010) Visible light induced photobleaching of methylene blue over melamine doped TiO2 nanocatalyst. Nanoscale 2(7):1109–1111Google Scholar

Books and Reviews

  1. Ahluwalia VK, Varma RS (2008) Alternative energy processes in chemical synthesis microwave, ultrasound and photo activation. Narosa Publishing House, New Delhi. ISBN 978-81-7319-848-9Google Scholar
  2. Ahluwalia VK, Varma RS (2009) Green solvents for organic synthesis. Narosa Publishing House, New Delhi. ISBN 978-81-7319-964-6Google Scholar
  3. Clark JH, Macquarrie D (2002) Handbook of green chemistry and technology. Blackwell Science, OxfordGoogle Scholar
  4. Kappe CO, Stadler A (2005) Microwaves in organic and medicinal chemistry. Wiley-VCH, Weinheim, p 410Google Scholar
  5. Kappe CO, Dallinger D, Murphree SS (2009) Practical microwave synthesis for organic chemists – strategies, instruments, and protocols. Wiley-VCH, Weinheim, p 296Google Scholar
  6. Matlack AS (2001) Introduction to green chemistry. Marcel Deckers, New YorkGoogle Scholar
  7. Nadagouda MN, Varma RS (2009) Risk reduction via greener synthesis of noble metal nanostructures and nanocomposites. In: Linkov I, Steevens J (eds) Nanomaterials: risks and benefits-proceedings of the NATO advanced workshop. Springer, Faro, pp 209–218Google Scholar
  8. Polshettiwar V, Varma RS (2009) Environmentally benign chemical synthesis via mechanochemical mixing and microwave irradiation. In: Ballini R (ed) Eco-friendly synthesis of fine chemicals, RSC green chemistry book series. RSC, Cambridge, England, pp 275–292Google Scholar
  9. Polshettiwar V, Varma RS (2009) Non-conventional energy sources for green synthesis in water (microwave, ultrasound, and photo). In: Li C-J, Anastas PT (eds) Handbook series, Handbook of green chemistry, Vol. 5: reactions in water. Wiley-VCH, Weinheim. ISBN 978-3-527-31574-1Google Scholar
  10. Polshettiwar V, Varma RS (eds) (2010) Aqueous microwave chemistry: synthesis and applications, vol 7, RSC green chemistry series. Royal Society Chemistry, Cambridge, UKGoogle Scholar
  11. Strauss CR, Varma RS (2006) Microwaves in green and sustainable chemistry. In: Larhed M, Olofsson K (eds) Microwave methods in organic synthesis, vol 266, Series in topics in current chemistry. Springer, Heidelberg, pp 199–231Google Scholar
  12. Varma RS (2000) Environmentally benign organic transformations using microwave irradiation under solvent-free conditions. In: Anastas PT, Tundo P (eds) Green chemistry: challenging perspectives. Oxford University Press, Oxford, pp 221–244Google Scholar
  13. Varma RS (2000) Expeditious solvent-free organic syntheses using microwave irradiation. In: Anastas PT, Heine L, Williamson T (eds) Green chemical syntheses and processes, Chapter 23, vol 767, ACS symposium series. American Chemical Society, Washington, DC, pp 292–312Google Scholar
  14. Varma RS (2001) Microwave organic synthesis. In: Geller E (ed) McGraw-Hill Yearbook of Science and Technology 2002. McGraw-Hill, New York, pp 223–225Google Scholar
  15. Varma RS (2006) Microwave technology: chemical synthesis applications. In: Seidel A (ed) Kirk-Othmer on-line encyclopedia of chemical technology, vol 16, 5th edn. Wiley, Hoboken, pp 538–594Google Scholar
  16. Varma RS, Ju Y (2005) Microwaves in organic synthesis. In: Afonso CAM, Crespo JG (eds) Solventless reactions (SLR), Chapter 2.2. Wiley-VCH, Weinheim, pp 53–87Google Scholar
  17. Varma RS, Ju Y (2006) Organic synthesis using microwaves and supported reagents. In: Loupy A (ed) Microwaves in organic sSynthesis, Chapter 8, 2nd edn. Wiley-VCH, Weinheim, pp 362–415Google Scholar

Copyright information

© Springer Science+Business Media New York 2013

Authors and Affiliations

  1. 1.Sustainable Technology Division, National Risk Management Research LaboratoryU.S. Environmental Protection AgencyCincinnatiUSA

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