Journal of Molecular Structure, zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFED 274 (1992) 7582 Elsevier Science Publishers B.V., Amsterdam 75 Basicity, IR spectra and protonation of some proton sponges in acetonitrile B. Brzezinski”, G. Schroeder”, E. Grechb, Z. Malarski” and L. Sobczykc “Faculty of Chemistry, A. Mickiewicz University 60-780 Poznari (Poland) bInstitute of Fundamental Chemistry, Technical University, 71-065 Szczecin (Poland) “Institute of Chemistry, University of Wroclaw, 5@383 Wroclaw (Poland) (Received 27 April 1992) zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFED Abstract The PK. values in acetonitrile for three proton sponges, l&bis(dimethylamino)naph- thalene (DMAN), 1,8-bis(dimethylaminomethyl)naphthalene (DMAMN) and 1,2- bis(dimethylaminomethyl)benzene (DMAMB), were determined. The relations between basicity and structure, and the infrared behaviour of the intramolecular NHN hydrogen bonds formed via protonation by phenols is discussed. It was found that an increase in the basicity of a sponge favours deprotonation of the phenols, while at the same time the strength of the NHN’ hydrogen bond diminishes. INTRODUCTION It has previously been shown that the proton sponge l,Sbis(dimethyl- amino)naphthalene (DMAN) in acetonitrile undergoes protonation depend- ing on the type of proton donor and its pK, [l-4]. The importance of species containing two or more acid molecules was emphasized, the homocon- jugated [ROHORI- anions being of particular importance. For a clearer insight into the influence of the structure of a sponge on its basicity and on the protonation process, we decided to compare the pK, values and reac- tivities in acetonitrile of 1,2-bis(dimethylaminomethyl)benzene (DMAMB) and 1,8-bis(dimethylaminomethyl)naphthalene (DMAMN) with previously studied DMAN. Correspondence to: Professor L. Sobczyk, Institute of Chemistry, University of Wroclaw, F. Joliot-Curie 14, 50-383 Wroclaw, Poland. OO22-2860/92/$05.00 0 1992 Elsevier Science Publishers B.V. All rights reserved.