(8) As the larger columns are run under vacuum, additional solvent can be run in as needed. Thus, the column need only be tall enough to contain the initial silica gel slurry. The 120-mm- diameter column is 210 mm long, and the 170-mm-diameter column is 270 mm long.(9) Use of vacuum-driven column chromatography has previously been described: Targett, NM; Kilcoyne, JP; Green, BJ Org. Chem. 1979,
