The weak antisymmetric vibration of C–O–C is in 1161 cm−1 of the glycoside links, while the 1106 cm−1 vibration is probably due to the C–O group which belongs to the same secondary alcohol as the one at the origin of the OH stretch mode at 3277 cm−1. The most intense band is in 1033 cm−1 due to C–O group of C6H2–O6H primary alcohols in dominant conformation, while its secondary conformation is observed in 1000 cm−1. The next band in 1055 cm−1 is due also to C–O group of C3–O3H secondary alcohols .