Microwave heating of solvents

Table of Contents

Microwave radiation interacts with materials through reflection, transmission or absorption. Polar substances and ions absorb microwave radiation well, which heats up the medium (see 1.3.2). With regard to their microwave absorption, a distinction is made between good, medium and poorly absorbing organic solvents, depending on their polarity. Non-polar and therefore poorly absorbing solvents can still be heated in the microwave. To do this

  • non-polar solvents are mixed with polar solvents if this is possible. A common example is the extraction of environmental samples according to EPA 3546 with acetone : hexane (1:1)
  • or heating elements are added to the solution. These are chemically inert materials (e.g. Carboflon consisting of 25% graphite in PTFE) that strongly absorb microwave radiation and then transfer the energy to the solution.
Poor (non-polar) Medium Good (polar)
Chloroforme Water Methanol
Dichloromethane Acetonitrile Ethanol
Carbon tetrachloride Acetone 2-Propanol
n-Hexane Ethyl acetate 1-Butanol
Toluene Tetrahydrofuran (Ethylene glycol)