  Acetylene (C$_2$H$_2$) and ethane (C$_2$H$_6$) are both produced in the
stratosphere of Jupiter via photolysis of methane (CH$_4$). Despite this common
source, the latitudinal distribution of the two species is radically different,
with acetylene decreasing in abundance towards the pole, and ethane increasing
towards the pole. We present six years of NASA IRTF TEXES mid-infrared
observations of the zonally-averaged emission of methane, acetylene and ethane.
We confirm that the latitudinal distributions of ethane and acetylene are
decoupled, and that this is a persistent feature over multiple years. The
acetylene distribution falls off towards the pole, peaking at
$\sim$30$^{\circ}$N with a volume mixing ratio (VMR) of $\sim$0.8 parts per
million (ppm) at 1 mbar and still falling off at $\pm70^\circ$ with a VMR of
$\sim$0.3 ppm. The acetylene distributions are asymmetric on average, but as we
move from 2013 to 2017, the zonally-averaged abundance becomes more symmetric
about the equator. We suggest that both the short term changes in acetylene and
its latitudinal asymmetry is driven by changes to the vertical stratospheric
mixing, potentially related to propagating wave phenomena. Unlike acetylene,
ethane has a symmetric distribution about the equator that increases toward the
pole, with a peak mole fraction of $\sim$18 ppm at about $\pm50^{\circ}$
latitude, with a minimum at the equator of $\sim$10 ppm at 1 mbar. [...] The
equator-to-pole distributions of acetylene and ethane are consistent with
acetylene having a shorter lifetime than ethane that is not sensitive to longer
advective timescales, but is augmented by short-term dynamics, such as vertical
mixing. Conversely, the long lifetime of ethane allows it to be transported to
higher latitudes faster than it can be chemically depleted.
