Spectroscopic and chemical reactivity manifestations of strong hydrogen bonding: HCNH proton-proton coupling and alkylation reactions of amines

Article abstract of DOI:10.1139/v82-250

Two useful but quite different manifestations of strong hydrogen bonding in systems containing NH groups are reported and discussed.The pK_a limit for observation of proton-proton HNCH spin-spin coupling in N-methylanilines is shown to be related to the strength of added H-bond electron donors so that PH₃PO, Ph₃AsO, and F^- in particular are useful reagents for resolving this type of coupling.The mechanism of hydrogen exchange between anilines and water and the role of the added electron donors are discussed.Strong H-bonding between anilines or benzylamines and F^- causes pronounced changes in the chemical reactivity of the amine.Results of experiments on the alkylation of these amines using potassium and tetra-n-butylammonium fluorides demonstrate the synthetic utility of this effect.