Acetic anhydride reacts rapidly and irreversibly with alcohols like ethanol, especially at elevated temperatures; upon solvation any residual acetic anhydride-D 6 forms trideuterated acetic acid (AcOH-D 3 ) and trideuterated ethyl acetate (EtOAc-D 3 ), which both join the mother liquor and wash cleanly away from the CBN-OAc crystals. However, if any residual acetic anhydride-D 6 remained in the sample and was responsible for the formation of Nbenzylacetamide, the C resonance from the resultant trideuterated acetate methyl carbon would split into a septet, rather than the observed quintet.