[Babcock_Hall]

Yesterday we recrystallized the post-silica product from a mixture of toluene and heptane.  Compared to the crude product prior to the silica gel column, this material is more crystalline.  Relative to the material after the column, the recrystallization improved the purity (as judged by H-1 NMR), although I would not call this material perfectly pure.  My guess is that it is sufficiently pure for routine applications. 

To recap, the starting material had an impurity by H-1 NMR.  It is conceivable that Oxone reacted with this impurity to produce something else.  I am ordering starting material from a different supplier, and I will check its purity before use.