Sulfonation of Procyanidin Polymers: Evidence of Intramolecular Rearrangement and Aromatic Ring Substitution

Abstract

The reaction of Douglas-fir polymeric procyanidins with aqueous sodium hydrogen sulfite was investigated by gel permeation chromatography (GPC) and the Isolation and Identification of sulfonated derivatives. GPC profiles of molecular weight over time indicated that epicatechin-(4ß)-sulfonate was rapidly formed initially but did not significantly increase over longer reaction time. Undefined oligomeric materials remained in the reaction mixture, which suggests that other reactions compete with simple acid-catalyzed cleavage of the interflavanoid bond and subsequent formation of 4-substituted flavanoid sulfonates. The Isolation of disodium epicatechin-(4,5')-disulfonate and a functionalized chromene derivative gave evidence that aromatic ring Sulfonation and flavanoid C-ring isomerization are t wo such reactions.'Paper 2898 of the Forest Research Laboratory, Oregon State University, Corvallis, OR 97331, U. S. A. Polymeric procyanidinsDouglas-fir (Pseudotsuga menzesii) inner bark was stripped from a freshly fallen tree, cut into Strips, and iinmersed in methanol.Holzforschung / Vol. 48 / 1994 / No. 2

Condensed Tannin Reacts with SO2 during Wine Aging, Yielding Flavan-3-ol Sulfonates

“…Foo et al first investigated the reaction of loblolly pine (Pinus taeda L.) bark tannins with sodium hydrogen sulfite and revealed that the major products are epicatechin-(4β)-sulfonate and sodium epicatechin-(4β → 8)-epicatechin-(4β)-sulfonate. This tannin sulfonation in the presence of SO 2 was further studied by others in the leather industry. − In the adhesive industry, sulfonation of condensed tannins is commonly used to enhance their solubility and reduce their viscosity in water…”