Studies on the boronation of methyl-beta-D-cellobioside--a cellulose model.
The conversion of phenylboronic acid (PBA) with methyl-beta-D-cellobioside (Me-beta-D-clb) and cellodextrins (DP(w) 12) was investigated to gain a basic understanding of the interactions of boric acid derivatives with oligo- and polyglucans. By means of MS and NMR experiments, it was possible to show a first stage formation of a six-membered ring at C-4 and C-6 of the non-reducing glucose occurs as in the case of monosaccharides. If the amount of reagent is increased the formation of seven-membered rings at the secondary OH moieties is observed. Even the existence of two of these large ring-systems in the direct neighborhood was found. Application of an excess of boronation reagent led to dimerization reactions of Me-beta-D-clb via the primary reducing glucose residue as confirmed by DOSY NMR studies. Preliminary (13)C NMR studies for the interaction of cellodextrins with PBA in DMSO solution confirmed a functionalization at the trans-1,2-diol moieties of these oligomers. The amount of reagent applied may either was shown to lead to soluble products or to insoluble cross-linked material.
Meiland
Marcel
M
Center of Excellence for Polysaccharide Research, Friedrich Schiller University of Jena, Humboldtstrasse 10, 07743 Jena, Germany.
Heinze
Thomas
T
Guenther
Wolfgang
W
Liebert
Tim
T
D001895:Boron / Q000737:chemistry*; D001897:Boronic Acids / Q000138:chemical synthesis / Q000737:chemistry; D002482:Cellulose / Q000031:analogs & derivatives / Q000737:chemistry*; D003912:Dextrins / Q000737:chemistry; D005960:Glucosides / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry
D001897:Boronic Acids; D003912:Dextrins; D005960:Glucosides; C082831:methyl beta-cellobioside; D002482:Cellulose; C068994:cellodextrin; C010686:benzeneboronic acid; D001895:Boron