MicrowavesWavelenght (λ): 0.1 cm - 100 cmFrequency (ν) : 300 MHz - 300 GHzThe Electric Field heats the substance due to ionic conduction and dipolar polarization
Microwave vs Conventional HeatingConvection currents Sample mix Sample Sample mix mix Heat conduction Microwaveheating Microwave irradiation You heat what you don’t want to heat (flask, vessel, reactor). Necessity of Lower energy heating up and consumption cooling down solvents for reaction and apparatus
Greenness of Microwave Synthesis Homogeneity of heating.Energy consumption of the synthesis Speed of heating. Clean, reproducible and easily automated. Microwave heating is efficiently used to force the organic chemical reactions!!! Under microwave irradiations, high and intense temperature can be achieved very quickly. According to Arrhenius equation, K =A∙e(-Ea/R∙T) microwaves oil bath heating mantle Higher temperature = Higher reaction rate
Greenness of Microwave SynthesisLow energy consumption: homogeneity and speed of heating.Faster reaction: minutes instead of hours or days (low energy consumption).Atom economy: greater yield, lesser wastage.Green solvents: H2O, EtOH, methanol and acetone are strongly responsive to microwave.Less or no solvent: possibility to carried out concentrated reaction. Possibility of neat condition or supported reagents.Rapid conditions screening: integrated on-line control guarantees safe operations.
List of Organic Reactions Carried Out by Microwave Irradiation Reactions in liquid phaseDiels-Alder, etero- Diels Alder, Alder-Bong reactionsSynthesis and hydrolisis of esters and amidesDifferent aliphatic nucleophilic substitutionsOxidation of alcholCondensation of malonic esthersCyclocondensations of varius eterocycle compoundsSynthesis of organometallic compoundsReactions in phase-transferSaponifications of hindered esthersDecarboxilationsSolvent-free reactionsAliphatic nucleophilic substitutionsHydrolisis of esters and amidesDehydration of alcholsOxidation of alchols