(C12H17N4OS)Cl

from The Collaborative International Dictionary of English v.0.48

vitamin B1 \vitamin B1\ n.
   a B vitamin {(C12H17N4OS)Cl} that prevents beriberi and
   maintains appetite and growth. Same as {thiamine}.

   Syn: thiamin, aneurin, antiberiberi factor.
        [WordNet 1.5]