Microwave-induced organic synthesis

FIGURE 7 A comparative account of "microwave-induced organic synthesis" (1986-2013). 

Simultaneous application of UV and MW irradiation has found widespread use in industry. The techniques are based on the conventional UV lamps and MW-powered electrodeless lamps and MW devices [28], The following paragraphs discuss several patents and papers that describe industrial microwave photochemistry, such as treatment of waste water, sterilization, or industrial photo induced organic synthesis. 

Bose, A.K. and Manhas, M.S., Banik, B.K. and Robb, E.W., Microwave-induced organic-reaction enhancement (MORE) chemistry - techniques for rapid, safe and inexpensive synthesis, Res. Chem. Intermed., 1994, 20, 1-11. 

Banik, B.K., Manilas, M.S., Kaluza, Z., Barakat, K.J. and Bose, A.K., Microwave-induced organic-reaction enhancement chemistry 4. Convenient synthesis of enantiopure ct-hydroxy-p Iaclams, Tetrahedron Lett., 1992, 33, 3603. 

Microwave-induced organic reaction enhancement chemistry techniques have been reported to allow highly accelerated synthesis of variously substituted vinyl-(3-lactams, using limited amounts of solvents and with efficient stereocontrol [3]. 

Liu H B, Microwave-induced plasma synthesis of organically encapsulated Ti02 nanoparticles , Chem Commun 1997 (10) 44-46 (in Chinese). 

Katritzky, A.R. and Singh, S.K., Synthesis of C-carbamoyl- 1,2,3-triazoles by microwave-induced 1,3-dipolar cycloaddition of organic azides to acetylenic amides, ]. Org. Chem., 2002,67, 9077-9079. 

A combination of different techniques can frequently improve yields of final compounds or synthetic conditions, for example a reunion of direct electrochemical synthesis and simultaneous ultrasonic treatment of the reaction system [715]. Reunion of microwave and ultrasonic treatment was an aim to construct an original microwave-ultrasound reactor suitable for organic synthesis (pyrolysis and esterification) (Fig. 3.7) [716], The US system is a cup horn type the emission of ultrasound waves occurs at the bottom of the reactor. The US probe is not in direct contact with the reactive mixture. It is placed a distance from the electromagnetic field in order to avoid interactions and short circuits. The propagation of the US waves into the reactor occurs by means of decalin introduced into the double jacket. This liquid was chosen by the authors of Ref. 716 because of its low viscosity that induces good propagation of ultrasonic waves and inertia towards microwaves. 

Among these new non-conventional methods in organic synthesis [103], microwave irradiation takes a particular place as it induces interactions between materials and waves of an electromagnetic nature assimilated to dielectric heating. This original procedure involves heating the materials which then become reactive in situations where traditional treatments failed to give any reaction at all. 

Several different organic transformations in the presence of homogeneous and heterogeneous catalysts have been described by Kappe et al. [73]. A review highlighting the immobilization of different catalysts used in organic synthesis induced by microwave heating has been published by the same research team [74]. 

A microwave-induced one-pot synthesis of olefins by Wittig olefination on polymer-supported triphenylphosphine has been reported [111]. Preparation of the Wittig reagent with in situ formation of the corresponding ylide was achieved in high yield within minutes, in contrast with several days by conventional methods. A variety of aldehydes and organic halides were reacted in the presence of the... 

Microwave-Induced Synthesis of Various Quinoline Derivatives Green Methodologies in Organic Synthesis... 

Liu, H (1997), Synthesis of Ti02 nanopowder enwrapped by organic membrane with microwave induced plasma method , Huaxue Tongbao, 10,44 6... 

The successfully generated chalcones could be cleaved by treatment with trifluoro-acetic acid or used for the subsequent synthesis of pyrimidines [45], Condensation of the polymer-bound chalcones with benzamidine hydrochloride under microwave irradiation for 30 min furnished the corresponding pyrimidines in good yields after TFA-induced cleavage. This new robust support/linker system for SPOT synthesis has been demonstrated to be compatible with a range of organic reactions and highly applicable for microwave conditions. 

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