The condensation of coniferyl alcohol with dissolved lignins of low molecular weight (LMWL) has been investigated. In aqueous sodium hydroxide (soda), sodium hydroxide - sodium sulfide (kraft) or sodium hydroxide - anthraquinone (soda-AQ) solutions, lignin preparations were heated and molecular weight distributions of the resultant condensation products were estimated. When coniferyl alcohol dissolved in soda and kraft liquors was heated, self-condensation was observed, mainly to form oligomers with only a small proportion of the reaction products characterized by molecular weights greater than about 1000. When mixtures of LMWL and coniferyl alcohol were heated in sodium hydroxide solutions, condensation reactions occurred and progressed further with increased temperature and concentration of coniferyl alcohol. In contrast to results with sodium hydroxide solutions, heating in kraft liquors gave rise to a higher proportion of the oligomer fraction and a smaller proportion of higher molecular weight entities. These results seem to indicate that the presence of sulfide reduces the extent of condensation reactions in alkaline pulping. With soda-AQ solutions, condensation effects were found to be intermediate between those observed with soda and kraft liquors.
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