title: Proton-acceptor properties and capability for mutarotation of some glucosylamines in methanol.
abstract: N-(m-Nitrophenyl)-beta-D-glucopyranosylamine (Gln), N-(N-methylphenyl)-beta-D-glucopyranosylamine (Glm), N-beta-D-glucopyranosylpyrazole (Glp), and N-beta-D-glucopyranosylimidazole (Gli) have been synthesized. Their basicity constants, pKb, determined in methanol were, respectively, 14.99, 14.36, 15.04, and 9.74. The derivatives of secondary amines (Glm, Glp, and Gli) did not mutarotate in methanol in the presence of 3,5-dinitrobenzoic acid and hydrochloric acid. The heats of formation and entropies were calculated by the AM1 and PM3 methods for the glucosylamines and their cations under consideration of two plausible protonation centers. Thermodynamic parameters for the proton transfer in the reaction: glucosylamine + CH3OH2+ = glucosylamineH+ + CH3OH were determined and the protonation center in the glucosylamine molecule was identified. The mechanism of mutarotation of the glucosylamines is discussed and the conclusion made that formation of an acyclic immonium cation is not a satisfactory condition for the reaction to proceed.
authors.affiliation: Faculty of Chemistry, University of Gdansk, Sobieskiego 18, PL-80-952 Gdansk, Poland.
authors.forename: Kazimiera
authors.initials: K
authors.lastname: Smiataczowa
authors.forename: Jarosław
authors.initials: J
authors.lastname: Kosmalski
authors.forename: Andrzej
authors.initials: A
authors.lastname: Nowacki
authors.forename: Małgorzata
authors.initials: M
authors.lastname: Czaja
authors.forename: Zygmunt
authors.initials: Z
authors.lastname: Warnke
mesh_terms: D002236:Carbohydrate Conformation; D005944:Glucosamine / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000737:chemistry*; D000432:Methanol / Q000737:chemistry*; D015394:Molecular Structure; D011522:Protons
chemical_list: D011522:Protons; D005944:Glucosamine; D000432:Methanol