Stoichiometry of reactions of ozone and hypochlorous acid with lignin and hexenuronic acid and its chlorination

Abstract The stoichiometry of ozone and hypochlorous acid reactions with lignin hexenuronic (HexA) was measured in bleaching experiments Eucalyptus sp. kraft pulp. progress the followed by UV Resonance Raman spectroscopy that can quantify HexA based on scattering intensities carbon–carbon double bond aromatic ring lignin. Here, one mol converted 0.16 (C9 monomer units) 0.28 HexA, whereas 1 0.09 0.23 HexA. use a tertiary amine catalyst treatments did not affect these stoichiometries. stoichiometric ratios showed more efficient oxidizing than acid, while both electrophiles reacted to similar extent. reaction concluded involve initial electrophilic chlorination bond, contributing significant organochlorine (OX) formation Evidence this linear correlation between content OX (0.59 per HexA) high xylan extracted from bleached 2D NMR HSQC TOCSY spectra isolated xylans disappearance signals after treatment appearance new spin system, yet be fully identified.