Observed acidities of charcoals, clays, and common laboratory purificationreagents in aqueous and organic solutions

In studying the purification and clarification of organic compounds with mi xtures of charcoals, clays, and chromatography supports in organic solution , we noted that the observed pH of the resulting slurry was an important fa ctor in determining which of the materials was appropriate. To examine this aspect of these purification methods, we determined the observed acidity o f several commercially available reagent-grade clays, decolorizing agents, chromatography supports, and several common laboratory drying reagents in w ater and in several organic solvents. As expected, we found that clays, dec olorizing carbons, and filter aids cannot be assumed to be pH neutral and n onreactive with organic molecules. For the purification of organic compound s with pH-sensitive functionalities, the potential acidity or basicity of a clarification reagent in the chosen solvent should be considered.