C6H5.NO2

from The Collaborative International Dictionary of English v.0.48

nitro- \ni"tro-\pref.
   1. A combining form or an adjective denoting the presence of
      niter.
      [1913 Webster]

   2. (Chem.) A combining form (used also adjectively)
      designating certain compounds of nitrogen or of its acids;
      as nitrohydrochloric, nitrocalcite; also, designating the
      group or radical {NO2}, or its compounds, as nitrobenzene
      ({C6H5.NO2}).
      [1913 Webster]

   {Nitro group}, the radical {NO2}; -- called also {nitroxyl}.
      [1913 Webster]

from The Collaborative International Dictionary of English v.0.48

Nitrobenzene \Ni`tro*ben"zene\ (? or ?), n. [Nitro- + benzene.]
   (Chem.)
   A yellow aromatic liquid ({C6H5.NO2}), produced by the action
   of nitric acid on benzene, and called from its odor
   {imitation oil of bitter almonds}, or {essence of mirbane}.
   It is used in perfumery, and is manufactured in large
   quantities in the preparation of aniline. Fornerly called
   also {nitrobenzol}.
   [1913 Webster] Nitrobenzol

from The Collaborative International Dictionary of English v.0.48

niacin \niacin\ n.
   A B vitamin (vitamin B5) essential for the normal function of
   the nervous system and the gastrointestinal tract. Called
   also {nicotinic acid} and {antipellagra vitamin}. Chemical
   formula {C6H5NO2}, chemically it is 3-pyridinecarboxylic
   acid.

   Syn: nicotinic acid.
        [WordNet 1.5]

from The Collaborative International Dictionary of English v.0.48

nicotinic acid \nic`o*tin"ic ac"id\, n. (Chem.)
   An organic acid ({C6H5NO2}), a carboxylated derivative of
   pyridine, obtained by the oxidation of nicotine; called also
   {niacin} and {antipellagra vitamin}, and {vitamin B5}.
   Chemically it is 3-pyridinecarboxylic acid.

   Note: It is a cofactor in several enzymatic reactions, and is
         used to prevent a pellagra-like disease in dogs.
         --[MI11]

   Syn: 3-pyridinecarboxylic acid, niacin, antipellagra vitamin.
        [1913 Webster +PJC]