c8h4no2

from The Collaborative International Dictionary of English v.0.48
Isatogen \I*sat"o*gen\, n. [Isatin + -gen.] (Chem.)
   A complex nitrogenous radical, {C8H4NO2}, regarded as the
   essential residue of a series of compounds, related to
   isatin, which easily pass by reduction to indigo blue. --
   {I*sat`o*gen"ic}, a.
   [1913 Webster]
    

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