Organic Synthesis Promoted by Microwave Radiation

Microwaves act as a high-frequency electric field hence, they warm up all materials possessing a mobile electric charge, such as polar molecules in an apolar solvent. Polar solvents are also warmed up by microwaves since their molecules are forced to rotate in the electric field and lose energy by collisions. 

The following examples illustrate the application of microwave technology in organic synthesis. 

Example 6.6 The Heck reaction, coupling aryl halides with a vinyl group, is promoted by microwaves and in situ prepared Pd(II) complex with V(ortho-to y )j, ligand in ionic liquid l-butyl-3-methylimidazolium hexafluorophosphate (bmim) [30]. 

High pressure in microreactors is often solved using diy media or media without solvents. This process starts hy adsorption of reagents or catalyst on one or more inorganic supports transparent to microwaves, such as silicates, alumosilicates or clays, or acts as a strong absorber of microwaves such as graphite. 

As yet, nearly all important synthetic reactions are performed under microwave conditions on a laboratory scale with the aim to become the method of choice in kilo laboratories of the pharmaceutical industry using commercially available microwave reactors [32]. 

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