The Diels-Alder Reaction of 2,5-Dialkylfurans and Fumaronitrile Revisited

Article abstract of DOI:10.1016/S0040-4020(01)89565-X

The equilibrium reactions of furan and 2,5-dialkyl derivatives with fumaronitrile were investigated under standard conditions (3.0*10^-4M) at four different temperatures in chloroform-d as solvent.Plots of lnK against 1/T were linear for each member of the series.The results show that the equilibrium concentration of adduct is sensitive to substituents.At equilibrium, there is a greater proportion of adduct derived from 2,5-dimethylfuran than from furan itself.However, as the length of the substituent chains is increased, the proportion of adduct decreases.Similar trends are also apparent from a more limited study of the equilibria in methanol-d₄ and acetone-d₆ as solvents.The concentrations of adduct in the equilibrium mixtures are highest in chloroform-d and lowest in acetone-d₆.AM1 calculations are reported for model adduct structures.