[1] It is a process of separation, purification and concentration of natural products, complex and thermally sensitive molecules for example vitamins and polyunsaturated fatty acids.
This process is characterized by short term exposure of the distillate liquid to high temperatures in high vacuum (around 10−4 mmHg) in the distillation column and a small distance between the evaporator and the condenser around 2 cm.
The motion of molecules is in the line of sight, because they do not form a continuous gas anymore.
This process has the advantages of avoiding the problem of toxicity that occurs in techniques that use solvents as the separating agent, and also of minimizing losses due to thermal decomposition.
[2] Molecular stills were historically used by Wallace Carothers in the synthesis of larger polymers, as a reaction product, water, interfered with polymerization by undoing the reaction via hydrolysis, but the water could be removed by the molecular still.