There seems to be a lot of confusion and misuse of terminology in this type of equipment. So, below are some points to keep in mind:
A. Molecular distillation is the same thing as short-path distillation. These both imply use of high vacuum and a condensing surface in close proximity to a heated evaporation surface. For many applications such as cannabinoids and other compounds with even greater molecular weight and boiling points, if this distance is not close, the equipment will not work well, if at all.
B. Some people associate the term “short-path” only with a basic glassware setup involving a basic boiling flask with a neck leading to a condenser and a receiver flask(s), or else a similar variation called a KIugelrohr. These are also referred to as pot stills, (in the vessel, not marijuana sense), and are all considered batch mode apparatus. But these are only one type (and the simplest) of short-path or molecular still – there are other forms, including Pope’s continuous mode WFMS.
C. Molecular stills are not fractional stills. Fractional still equipment implies utilization of a vertical packed column providing multiple equilibrium stages or “theoretical plates”, requiring the condenser to be further away from the boiling flask and reached only after the sometimes quite long obstacle of the packed column, a problem for heat sensitive materials such as cannabinoids. The single theoretical plate of molecular stills is sufficient for most cannabinoid work and offers the least product degradation (Pope does offer fractional distillation equipment of several different types and size ranges for other applications).