Conformations vinyl alcohol/thiol

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... 

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. 

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