Reactions of Secondary amines with Their N-(2,4-Dinitro-1-naphthyl)Derivatives To Form Jackson-Meisenheimer Adducts. Substantial Difference in Reaction Rates between Pyrrolidine and Piperidine

Article abstract of DOI:10.1021/ja00406a033

Pyrrolidine, piperidine, and butylmethylamine react with their respective N-(2,4-dinitro-1-naphthyl) derivatives to form ? adducts as through the respective amide ions had attached at the 1 position.These reactions occur in dimethyl sulfoxide solution and proceed to a state of equilibrium.For the pyrrolidine and butylmethylamine reactions, equilibrium constants as well as rate constants both foward and reverse have been measured.Although two amine molecules are required to form the ? adduct, one to supply an amino moiety and the other to receive a proton, the forward reaction is only first order in amine; therefore, amine attack is not base catalyzed.Piperidine reacts so much slower than pyrrolidine, roughly 1/400th as fast, that rate and equilibrium measurements were inconvenient.The low reactivity of the piperidine system is ascribed to stereoelectronic/conformational/steric problems in the piperidino moiety of N-(2,4-dinitro-1-naphthyl)piperidine as it enters the transition state.