J. Bartmess, R. Hays, H. Khatri
Aug 1, 1981
Citations
0
Influential Citations
30
Citations
Journal
ChemInform
Abstract
The gas-phase negative ion-molecule chemistry of 1,3-dithianes and 1,3-dithiolanes differs considerably from that in solution. When treated with anionic bases, 1,3-dithiane undergoes successive elimination reactions giving thiolates, in competition with deprotonation at the 2 carbon, which is the sole solution phase reaction channel. The appearance of the various product ions with changing base strength agrees with their calculated thermochemical onset. The gas-phase acidity of 1,3-dithiane is measurable if the elimination reaction is blocked by gem-dimethyl substitution at the 5 carbon. For 1,3-dithiolane, no deprotonation product is observed, even at thermochemical threshold, cycloreversion to RCS, and ethylene occurs. This competes with successive eliminations to thiolates, as with the six-membered ring. The differences between the gas phase and solution reactivities are rationalized in terms of counterion effects. The use of 2-lithio-l,3-dithianes 2 as acyl anion equivalents has since its inceptionZ become an important technique in synthetic organic ~ h e m i s t r y . ~ These species are equally intriguing to physical organic chemists, due to the considerable stabilization 0002-7863/81/1503-4746$01.25/0