pKa-Values of Guaiacyl and Syringyl Phenols Related to Lignin

Abstract The literature relating to the pKa -values of guaiacyl- and syringyl-derived phenols has been thoroughly surveyed and summarized. In addition, the pKa -values of a number of guaiacyl, syringyl and other phenols related to lignin have been determined using a spectrophotometric method combined with multivariate evaluation. Differences and similarities between the acidities of a number of substances are extensively discussed. The pKa -value strongly affects the delignification during pulping, bleaching and leaching of lignin during pulp washing.