Download - Notes On Microwaves


2. Microwave Apparatus Waveguide FeedMagnetronOven Cavity 3. MicrowavesWavelenght (): 0.1 cm - 100 cmFrequency () : 300 MHz - 300 GHzThe Electric Field heats thesubstance due to ionicconduction and dipolar polarization 4. Microwave vsConventional HeatingConvection currents Sample mixSampleSample mix mixHeat conductionMicrowaveheatingMicrowave irradiation You heat whatyou dont want toheat (flask, vessel,reactor). Necessity ofLower energyheating up and consumptioncooling downsolvents forreaction andapparatus 5. Greenness of Microwave SynthesisHomogeneity of heating.Energy consumption of the synthesisSpeed of heating.Clean, reproducible and easily automated. Microwave heating is efficiently used to forcethe organic chemical reactions!!!Under microwave irradiations, high and intensetemperature can be achieved very quickly.According to Arrhenius equation, K =Ae(-Ea/RT) microwaves oil bath heating mantleHigher temperature = Higher reaction rate 6. 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 safeoperations. 7. ListofOrganic ReactionsCarried OutbyMicrowave 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 8. Advances in Laboratory Microwave Systems 9. Industrial Microwave Reactors