In search of neutral organic superbases—iminopolyenes and their amino derivatives

Abstract

The intrinsic proton affinities of iminopolyenes and their amino derivatives are considered. It is shown that substitution of amino groups at strategic positions increases proton affinity (PA) to superbasic values particularly in branched polyenes. It follows that the number of double bonds, selection of the conformations and a judicious choice of substituents offer a closely spaced ladder of highly basic compounds spanning the range of values of PAs between 206.5 and 271.9 kcal mol−1, which might be of some importance in acid–base chemistry. This conclusion is strengthened by the fact that several of the studied amino derivatives of iminopolyenes exhibit very high pKa values between 30.0–33.5 in acetonitrile. Hence, they qualify as candidates for powerful neutral organic superbases.