-yne

-ine \-ine\ (?; 104).
   1. (Chem.) A suffix, indicating that those substances of
      whose names it is a part are basic, in their nature, i.e.
      contain a basic nitrogen group.
      [1913 Webster +PJC]

   Note: All organic bases, and basic substances (especially
         nitrogenous substances), are systematically written
         with the termination -ine; as, quinine, pyridine,
         morphine, guanidine, etc. Certain substances containing
         nitrogen though with net neutral character (as certain
         amino acids) also end in -ine, such valine and glycine.
         All indifferent and neutral substances, as proteids,
         glycerides, glucosides, etc., should commonly be
         spelled with -in; as, gelatin, amygdalin, etc. This
         rule has no application to those numerous commercial or
         popular names with the termination -ine; as, gasoline,
         vaseline, etc.
         [1913 Webster +PJC]

   2. (Organ. Chem.) A suffix, formerly used to indicate
      hydrocarbons of the second degree of unsaturation; i. e.,
      members of the acetyline series; as, hexine, heptine,
      etc., but now superseded by the ending {-yne}, as in
      propyne.
      [1913 Webster +PJC]