A 300 MHz Study of Melibiose, Lactose and 3‐Keto‐Lactose in D₂O

Abstract

Abstract The 300 MHz 1 H‐n.m.r. spectra of β‐D‐allose (1), α‐D‐galactopyranosyl‐(1 → 6)‐D‐glucopyranose (melibiose) (2), β‐D‐galactopyranosyl‐(l → 4)‐D‐glucopyranose (lactose) (3) and O‐β‐D‐xylo‐hexopyranosyl‐3‐ulose‐(1 → 4)‐D‐glucopyranose (3‐keto‐lactose) (4) are discussed. From comparative considerations of shift increments caused by several substitutions (e.g. downfield shift of 0.1‐0.2 p.p.m. of an axial proton by the presence of a synaxial and a vicinal axial OH, but an absence of any effect on the equatorial proton) it is corroborated that 3‐keto‐lactose occurs in the hydrated form in D 2 O.