The Collaborative International Dictionary of English v.0.48:

Pyrazine \Pyr"a*zine\, n. Also -zin \-zin\ . [Pyridine + Gr. ?
   not + ? life.] (Org. Chem.)
   A feebly basic solid, C4H4N2, obtained by distilling
   piperazine with zinc dust, and in other ways. Also, by
   extension, any of various derivatives of the same.
   [Webster 1913 Suppl.]