Solvents properties under microwave

The heating characteristics of a particular material (for example, a solvent) under microwave irradiation conditions are dependent on the dielectric properties of the material. The ability of a specific substance to convert electromagnetic energy into heat at a given frequency and temperature is determined by the so-called loss tangent, tan <5. The loss factor is expressed as the quotient tan (3 = "/ , where e" is the dielectric loss, indicative of the efficiency with which electromagnetic radiation is... 

The synthesis of benzo[Z>]furan derivatives has become a very active field because these molecules have been recently identified as having a variety of biological activities. For example, they can function as inhibitors of protein tyrosine phosphatase IB with antihyperglycemic properties <00JMC1293>, as well as potent and short-acting p-blockers in the treatment of various cardiovascular diseases . An inexpensive, reusable clay has been utilized to catalyze a facile cyclodehydration under microwave without solvent to form 3-substituted benzo[2>]furans from substituted a-phenoxy acetophenones 104. One of the important features of this procedure is that all the selected cyclodehydration reactions are complete in less than 10 minutes <00SL1273>. 

Langa, who has reported several C o derivatives with intramolecular PET processes, recently described the synthesis under microwave irradiation conditions of two pyrazolino [60]fullerene (58a,b) bearing electron-withdrawing substituents. The resulting fullerene derivatives were highly soluble in several polar and nonpolar solvents, and electrochemical studies revealed improved electron-acceptor properties compared with unmodified Ceo [63]. 

Cr Oj nanoparticles were prepared by Farzaneh (2011) using CifNOjlj.OHjO as starting material, triethanolamine (TEA) as template and water as a green solvent under microwave irradiatioa The particle size of Cr Oj was between 25-70 mn. The catalytic activity of the prepared Cr Oj nanoparticles was found to be more than the bulk sample in the epoxidation of notbomene with 70% activity and 95% selectivity while microwave-assisted synthesis and luminescent properties of pure and doped ZnS nanoparticles were studied by Yang et al. (2012). 

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