Coniferyl alcohol is generated from the cleavage of β-O-4 bonds during alkaline pulping of hardwoods and softwoods. Once formed, some of the coniferyl alcohol (CA) is transformed into vinylguaiacol (VG) and isoeugenol (IE). All three of these compounds (CA, VG, and IE) can rearrange to quinone methides (QMs) under alkaline conditions and become involved in condensation reactions with lignin and carbohydrate moieties. The aim of this investigation was to see if ethylguaiacol (EG) addition to soda-AQ (SAQ) pulping systems would lead to its reaction with the QMs from CA, VG, and IE to form dimers that are unreactive towards further condensation. Sugar maple wood meal was delignified by the SAQ process with EG added at 5.0 wt% on wood meal. Three dimers were detected in the pulping effluent and identified as a combination of EG with CA, VG, and IE. The total yield of the three dimers corresponded to ∼80% of the estimated CA that would have been generated. Conventional kraft, SAQ, and SAQ+EG pulping of the maple chips were then performed. The bleachability of the SAQ+EG pulp was significantly improved as compared to the SAQ pulp and it was estimated to be superior to the kraft pulp as well.

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High kappa number kraft and soda-anthraquinone (soda-AQ or SAQ) pulps from sugar maple (Acer saccharum) were investigated to see how the lignin-carbohydrate complexes (LCC) they contained affected lignin removal by oxygen, chlorine dioxide, and hydrogen peroxide. The chlorine dioxide and hydrogen peroxide doses were higher than normal because both pulps had unbleached kappa numbers in the range of 61-62. Only oxygen delignification was investigated with the SAQ pulp. The research focused on the strong lignin-carbohydrate (L-C) linkages only. The pulp carbohydrates were enzymatically degraded and solubilized, thus leaving an enzymatic lignin (EL) residue. The highest concentration of bound sugars (glucan, xylan, arabinan, and galactan) on any of the ELs was <2.1 wt%. Chlorine dioxide (D stage) was investigated at end pHs of 2.1, 2.9, and 4.0, followed by extraction with dilute sodium hydroxide. Lignin oligomers containing bound glucan and arabinan were unreactive and accumulated in the fibers. When oxygen was used to delignify kraft and SAQ pulps by ~50%, only ~10% of the lignin bound arabinan was solubilized. Galacto-lignin complexes were somewhat reactive to oxygen and hydrogen peroxide under alkaline conditions, but less reactive in the D stages. Consistent with literature data, xylo-lignin complexes were reactive toward oxygen and toward the other two oxidants. They do not appear to be major impediments in the bleaching process.