The fate of formamide in a fragmenting protoplanetary disc
  Recent high-sensitivity observations carried out with ALMA have revealed the
presence of complex organic molecules (COMs) such as methyl cyanide (CH$_{\rm
3}$CN) and methanol (CH$_{\rm 3}$OH) in relatively evolved protoplanetary
discs. The behaviour and abundance of COMs in earlier phases of disc evolution
remains unclear. Here we combine a smoothed particle hydrodynamics simulation
of a fragmenting, gravitationally unstable disc with a gas-grain chemical code.
We use this to investigate the evolution of formamide (NH$_{\rm 2}$CHO), a
pre-biotic species, in both the disc and in the fragments that form within it.
Our results show that formamide remains frozen onto grains in the majority of
the disc where the temperatures are $<$100 K, with a predicted solid-phase
abundance that matches those observed in comets. Formamide is present in the
gas-phase in three fragments as a result of the high temperatures
($\geq$200\,K), but remains in the solid-phase in one colder ($\leq$150 K)
fragment. The timescale over which this occurs is comparable to the dust
sedimentation timescales, suggesting that any rocky core which is formed would
inherit their formamide content directly from the protosolar nebula.
