| Five cyclic ketene N,O-acetals 1--5 have been synthesized by the elimination of the corresponding 1,3-oxazolinium and 1,3-oxazinium iodide salts.;Several different nucleophilic substitution reactions have been studied in the ILs [BMIM]BF4 and [BMIM]PF6, and in acetone, acetonitrile, tetrahydrofuran and 1,4-dioxane. SN2 reactions were observed for the reactions of benzyl bromide, m-methoxybenzyl bromide and p-methoxybenzyl chloride with different nucleophiles in both [BMIM]BF4 and [BMIM]PF6.;SN1 reactions occurred with (1-bromoethyl)benzene and the nucleophiles Cl- and CN- in [BMIM]BF 4. I- is the possible crossover point for the transition from first order to second order substitution and elimination reactions. S N1 reactions were observed in [BMIM]PF6 when (1-bromoethyl)benzene reacted with F-.;Compared with acetone, acetonitrile, tetrahydrofuran and 1,4-dioxane, ILs favored the nucleophilic substitution reactions with the neutral nucleophile, Ph3P, and slows the reactions with charged nucleophiles. (Abstract shortened by UMI.)... |
