Vinyl thiol

Simulated annealing calculations were performed to acquire the mechanisms of thermolysis of thiirane and thiiranium cation <2002JMT71>. The AMPAC 6.55 package along with AIMl and SAMI methods were used to estimate structures, which were then used as starting points for further ab initio calculations. Critical points were confirmed by calculation of the vibrational frequencies. The primary reactions thiirane 19 —> S-f ethene, thiirane—> vinyl thiol 20, and thiirane ethanethial (thioacetaldehyde) 21 were examined for thermolysis of thiirane Scheme 1. Many secondary reactions were also examined. The simulated annealing method was predicted to be very useful in the future for the study of competing chemical reactions. 

The thermal decomposition of vinyl thiol, CH2=CHSH, appears to proceed by a molecular mechanism, similar to that of ethane thiol. This conclusion was derived indirectly from the thermal decomposition of ethylene sulfide at 1000 °C vide infra), in a fast flow system in which the major products are C2H4, C2H2 and H2S, the latter two compounds formed in equal quantities if the reaction products are quickly trapped out of the effluent stream, vinyl thiol can be detected. Preliminary results suggest the following steps... 

Effects of halogen substituents on the conformations of vinyl alcohol and vinyl thiol a... 

Studies on vinyl thiol (or ethene thiol) are scarce. It has been detected experimentally, and its formation from ethylene and singlet sulfur atom has been predicted theoretically [15]. Its conformations have been studied both experimentally [16] and theoretically [17). Using it, in a comparative way, in our study focused on vinyl alcohol seemed relevant. 

Effects of Halogen Substituents on the Conformations of Vinyl Alcohol and Vinyl Thiol... 

In vinyl thiol, we observe a very weak out of plane distortion of the anti con-former. Our results are in relatively good agreement with previous experimental... 

These calculations show that, if vinyl alcohol and vinyl thiol indeed mainly exist in planar syn conformations, as previously stated, the situation can be very different when halogen substituents are present. In some cases, the anti conformation is more or less out-of-plane staggered and can become more stable than the syn one. The general trends of substituent effects can be discussed by molecular orbitals analysis and electrostatic interactions. The results are subject to experimental confirmation, at least in the case of enols since their conformers can be prepared by the action of singlet oxygen atom on substituted ethylen, and trapped in low temperature matrices. 

In a similar approach, vinyl/thiol modified poly(dimethyl-co-diphenylsiloxanes) have been proposed... 

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