- The Gas-phase basicity and H/D Exchange Characteristics of the Parent Thiocarbonyl Enolate Anions
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The enethiolate anions corresponding to thioacetaldehyde and thioacetone, synthesized via elimination reactions, undergo H/D exchange reactions, demonstrating the intermediacy of the thiocarbonyl tautomers, and proton transfer reactions, leading to ΔG0acid = 341 +/- 3 kcal mol-1 and ΔG0acid = 344 +/- 3 kcal mol-1 (1 kcal = 4.184 kJ).
- Zhang, Lijian,Grabowski, Joseph J.
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p. 1819 - 1821
(2007/10/02)
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- Elimination, Fragmentation, and Proton Transfer in 1,3-Dithianes and 1,3-Dithiolanes in the Gas Phase
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The gas-phase negative ion-molecule chemistry of 1,3-dithianes and 1,3-dithiolanes differs considerably from the 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 appearence of the various product ions with changing base strength agrees with their calculated thermochemical onset.The gase-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 pbserved; even at thermochemical treshold, cycloreversion to RCS2- and ethylene occurs.This competes with successive elimination to thiolates, as with the six-membered ring.The differences between the gas phase and solution reactivities are rationalized in terms of counterion effects.
- Bartmess, John E.,Hays, Robert L.,Khatri, Hiralal N.,Misra, Raj N.,Wilson, Stephen R.
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p. 4746 - 4751
(2007/10/02)
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