\documentclass{ppex}
\nonstopmode
\usepackage {m-chemic}
\pagestyle{empty}
\setlength\textwidth{207.0pt}
\begin{document}
\ResetPreambleCommands
\ReadyForTheFray
\usepackage {m-chemic}
\startchemical[width=fit]
\chemical
  [SIX,B,C,ADJ1,FIVE,ROT3,SB34,
   +SB2,-SB5,Z345,DR35,SR4,CRZ35,
   SUB1,ONE,OFF1,SB258,Z0,Z28]
  [C,N,C,O,O,CH,COOC_2H_5,COOC_2H_5]
\stopchemical
\end{document}