  Titan's atmosphere is a natural laboratory for exploring the photochemical
synthesis of organic molecules. Significant recent advances in the study of the
atmosphere of Titan include: (a) detection of C$_3$ molecules: C$_3$H$_6$,
CH$_2$CCH$_2$, c-C$_3$H$_2$, and (b) retrieval of C$_6$H$_6$, which is formed
primarily via C$_3$ chemistry, from Cassini-UVIS data. The detection of
$c$-C$_3$H$_2$ is of particular significance since ring molecules are of great
astrobiological importance. Using the Caltech/JPL KINETICS code, along with the
best available photochemical rate coefficients and parameterized vertical
transport, we are able to account for the recent observations. It is
significant that ion chemistry, reminiscent of that in the interstellar medium,
plays a major role in the production of c-C$_3$H$_2$ above 1000 km.
