Infrared spectroscopic determination of the gas-phase thermal decomposition products of metal-ethyldithiocarbonate complexes

Article abstract of DOI:10.1016/S1386-1425(97)00144-3

Head-space analysis by gas-phase infrared spectroscopy (HAGIS) allows the facile examination of the decomposition mechanisms of the metal xanthates [metal-(O-alkyldithiocarbonates], Fe(EtOCS₂)₃, Zn(EtOCS₂)₃, Cu(EtOCS₂), Pb(EtOCS₂)₂ and Ni(EtOCS₂)₂, over the temperature range 25-120°C. These metal xanthates fall into two groups based on the generation of the primary gaseous decomposition products, CS₂, COS and CO₂. The first group, consisting of Fe(III) and Zn(II) xanthates, decompose readily, forming mostly CS₂ and COS in a constant ratio and leaving, initially, a metal-alkoxide residue. In the second group, decomposition is relatively small, generating CO₂ and COS, with the proportion of COS increasing as the temperature increases and CS₂ formation occurring only at the upper end of the temperature range. The residue is more of a metal-thioalkyl species in this case. Presumably, CO₂ is formed by re-insertion of COS into a metal alkoxide and elimination of CO₂, leaving a thioalkyl moiety. Volatile metal-xanthates are probably observed in the gas-phase, allowing examination of the changes concomitant to the vaporization of the discrete metal xanthates from network or partially associated solids.