Vaporization thiocarbonyl

In the flask A are placed 750 g. (6.3 moles) of granulated tin (Note 10) and 1500 cc. of commercial hydrochloric acid (about 28 per cent). The mixture is heated until the action is vigorous. The thiocarbonyl perchloride is run in from the funnel T (Note ii). The resulting reaction is very violent. The vapors are... 

The intervention of the vinylic alcohol structure obviously would not be detected in normal kinetic experiments. However, in the sulfur atom case, the sequence may well be arrested at the vinylic mercaptan stage. At lower pressures it is also possible that the vinylic mercaptan further iso-merizes to the thioaldehyde or thioketone structure, which would not be detected, since thiocarbonyls form solid trimers with very low vapor pressures. 

Thiocarbonyl fluoride, 9, is prepared in good yield by pyrolysis of 6 at ca. 600°C in the vapor phase or by carrying out the reaction of sulfur and tetrafluoroethylene at higher temperatures. A cleaner synthesis involves fluorination of thiophosgene dimer to tetrafluoro-l,3-dithietane, 10, followed by cracking of 10 to two molecules of 9 (7). 

The Stable carbonyl and thiocarbonyl halide molecules have been studied by IR as well as Raman spectroscopy. Normal coordinate analyses based on force constants transferred from other molecules (Urey-Bradley type), or from ab initio calculations, have aided in the vibrational assignments. Some of the unstable molecules which have been observed in the microwave have been characterized by infrared spectroscopy. The somewhat lower sensitivity of this method means that long path lengths of the gas may be needed. The identification of the various stable and unstable species in the microwave spectrum is simplified by the fact that the absorption lines are usually well resolved from each other. The widths of the bands in the infrared may make the transient species difficult to detect against the stronger absorptions of the stable side products. IR and Raman spectroscopies do have the advantage that they can be used on solid and liquid samples. Since the bands in a low temperature rare gas matrix have a narrower profile, the infrared spectrum is usually simplified over the room temperature gas phase spectrum. Moreover, the vibrational frequencies are only mildly perturbed by solid state effects. For example, CF Se has not been observed in the vapor phase, yet its vibrational dynamics are known from its matrix isolation spectrum. Table 9 gives the vibrational data for the carbonyl, thiocarbonyl, seleno-carbonyl and formyl halides. 

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