Isolation of pharmaceutical intermediates through solid supported evaporation. Batch operation mode

Solid supported evaporation (SSE) is a simple method to isolate dissolved compounds as a solid material. The solution is put in contact with granular porous polymer beads onto which the compounds deposit upon evaporation of the solvent. This brings some advantages over direct evaporation to dryness in terms of safety and handling of the solids. In this paper, SSE in batch mode is explored where the solution is added to the polymer beads at once, i.e. opposite to the semicontinuous mode where the solution is sprayed over a bed of beads. A number of compounds varying widely in their physical and chemical properties is studied. It is found that all compounds could be loaded onto the beads; however, the loading capacity depends on the properties of the compound and in general was lower than in the semicontinuous operating mode studied in an accompanying paper. For highly soluble compounds, higher loadings could be achieved when solvent evaporation was slow. In cases where tested, bead loading was found to be homogeneous within a batch. Recovery of compound from loaded beads was achieved by dispersing the beads in a solvent and washing of the filter cake after filtration. A relatively large amount of solvent is required to achieve full recovery.