The Collaborative International Dictionary of English v.0.48:

Muconic \Mu*con"ic\, a. [Mucic + itaconic.] (Chem.)
   Of, pertaining to, or designating, an organic acid (C6H6O4,
   2-4-hexadienedoic acid), obtained indirectly from mucic acid,
   and somewhat resembling itaconic acid. Various other means of
   synthesis have been reported.
   [1913 Webster +PJC]