Mass and microwave spectroscopic studies of the pyrolysates and pyrolysis mechanism of 1-chloro-2-isocyanatoethane and 1-chloro-2-isothiocyanatoethane

The pyrolysates of CICH2CH2NCO and ClCH2CH2NCS were investigated by pyrolys is-mass spectrometry and microwave spectroscopy (Py-MS/MW) at 100-900 degre es C. In the mass spectrum of the pyrolysate of CICH2CH2NCO a characteristi c ion is seen at mit 69, while in that of ClCH2CH2NCS ions at m/z 59, 62, 6 4, and 85 are observed. The identification by MW revealed that the ion at m /z 69 is the molecular ion of vinyl isocyanate, while the ion at mit 59 is that of isothiocyanic acid, at m/z 62 and 64 are those of vinyl chloride, a nd at m/z 85 is that of vinyl isothiocyanate. In spite of the similarity of the two compounds, it was found that the pyrolysis mechanism of CICH2CH2NC S was different from that of ClCH2CH2NCO. The generation of vinyl chloride and isothiocyanic acid from CICH2CH2NCS suggests that the C-N single bond o f CICH2CH2NCS may be weaker than that of ClCH2CH2NCO. (C) 2000 Elsevier Sci ence B.V. All rights reserved.