Ethyl (<i>Z</i>)-2-chloro-2-(2-phenylhydrazin-1-ylidene)acetate

The title compound, C(10)H(11)ClN(2)O(2), features an almost planar C(ar)-N(H)-N=C(Cl) unit [torsion angle = 0.8 (1)° whose phenyl substituent is almost coplanar with it [dihedral angle = 2.8 (2)°]; this unit is slightly twisted with respect to the carboxyl -CO(2) fragment [dihedral angle = 10.3 (2)°]. In the crystal, the amino group acts as a hydrogen-bond donor to the carbonyl O atom of an adjacent mol-ecule; the hydrogen bond generates a helical chain that runs along the b axis of the monoclinic unit cell.