Switchable Multiphase Systems
Arno Behr, Thomas Seidensticker, Dieter Vogt · 2025
This chapter describes different approaches of switchable multiphase systems considering different triggers, catalysts, and solvents used to realise such a behaviour. It explains the fundamentals of thermomorphic multiphase systems using ternary diagrams and the fundamentals of CO 2 -switchable media using corresponding chemical formulae. The chapter gives examples of suitable combinations of solvents having a temperature-dependent miscibility gap and a CO 2 -responsive behaviour. The switch between homogeneous and biphasic can be initiated by increasing and lowering the temperature (the so-called thermomorphic systems), or by the addition/removal of CO 2 . The chapter discusses these different switchable multiphase systems, starting with the temperature as a switch. Thermoregulated phase-transfer catalysis (TRPTC) involves modifying the catalyst ligands to become water soluble at room temperature. TRPTC has been successfully used in hydroformylations and reductions.