  The ketenyl radical (HCCO) has recently been discovered in two cold dense
clouds with a non-negligible abundance of a few 1e-11 (compared to H2) (Agundez
et al. 2015). Until now, no chemical network has been able to reproduce this
observation. We propose here a chemical scheme that can reproduce HCCO
abundances together with HCO, H2CCO and CH3CHO in the dark clouds Lupus-1A and
L486. The main formation pathway for HCCO is the OH + CCH -> HCCO + H reaction
as suggested by Agundez et al. (2015) but with a much larger rate coefficient
than used in current models. Since this reaction has never been studied
experimentally or theoretically, this larger value is based on a comparison
with other similar systems.
