Highly Fluorinated Cyclopentanones and Their Enols
摘要:
2H-Perfluorocyclopentanone (Ik) and its enol (le) have been independently synthesized and equilibrated. In carbon tetrachloride, the enol is the only detectable form at equilibrium. In addition to its high relative stability, this enol displays interesting reactivity, including reversible bromination and hydrolysis reactions. Replacing the vinyl fluorine of le with hydrogen changes the relative enol stability dramatically as the enol is only present to the extent of 13% in carbon tetrachloride under equilibrating conditions. In Lewis basic solvents, however, the enol is the only detectable form because of its strength as a hydrogen bond donor. Quantum mechanical calculations on both systems suggest that ketone destabilization, but not enol stabilization, by fluorination is responsible for the remarkable relative stability of the enols.
Highly Fluorinated Cyclopentanones and Their Enols
作者:Patrick E. Lindner、David M. Lemal
DOI:10.1021/jo9602940
日期:1996.1.1
2H-Perfluorocyclopentanone (Ik) and its enol (le) have been independently synthesized and equilibrated. In carbon tetrachloride, the enol is the only detectable form at equilibrium. In addition to its high relative stability, this enol displays interesting reactivity, including reversible bromination and hydrolysis reactions. Replacing the vinyl fluorine of le with hydrogen changes the relative enol stability dramatically as the enol is only present to the extent of 13% in carbon tetrachloride under equilibrating conditions. In Lewis basic solvents, however, the enol is the only detectable form because of its strength as a hydrogen bond donor. Quantum mechanical calculations on both systems suggest that ketone destabilization, but not enol stabilization, by fluorination is responsible for the remarkable relative stability of the enols.
Energetics of hydrate and hemiketal formation for highly fluorinated ketones
作者:Patrick E. Lindner、David M. Lemal
DOI:10.1016/s0040-4039(96)02149-1
日期:1996.12
Heats of hydration for a series of fluoroketones have been calculated at the HF/6-31G **//6-31G ** level, and equilibrium constants for hemiketalformation with trifluoroethanol have been measured for a related series. These reactions were found to be considerably more favorable in cyclic than in corresponding acyclic systems. Quantum mechanical calculations indicate that this difference can be traced