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Towards inhibition of yellowing of mechanical pulps .2. Water-soluble catalysts for the hydrogenation of lignin model compounds

TitleTowards inhibition of yellowing of mechanical pulps .2. Water-soluble catalysts for the hydrogenation of lignin model compounds
Publication TypeJournal Article
Year of Publication1997
AuthorsHu, TQ, James, BR, Lee, CL
JournalJournal of Pulp and Paper Science
Volume23
PaginationJ200-J205
Date PublishedMay
Type of ArticleArticle
ISBN Number0826-6220
Keywordsaromatic compounds, aromatic groups, CARBON-MONOXIDE, CARBONYL, CATALYSTS, CHROMOPHORES, CLUSTERS, colloids, GROUPS, HIGH-YIELD PULPS, HYDROGENATION, HYDROGENOLYSIS, INHIBITION, LIGNIN, mechanical pulps, model compounds, water solubles, yellowing
Abstract

Water-soluble, polymer-stabilized, colloidal rhodium is an effective catalyst for the hydrogenation of the aromatic rings of the lignin model compounds 4-propylphenol, 2-methoxy-4-propylphenol, and 1,2-dimethoxy-4-propylbenzene under extremely mild conditions (25 degrees C, 1 atm H-2) in a one-phase, aqueous ethanol medium. The water-soluble catalyst is prepared by reducing rhodium trichloride trihydrate with ethanol in the presence of polyvinylpyrrolidone (PVP) and triethylamine, The reactivity of various chromophore precursors in lignin toward hydrogenation catalyzed by water-soluble, colloidal rhodium follows the descending order of carbon-carbon double bond > aromatic ring in 4-propylphenol > carbonyl group and the aromatic rings in 2-methoxy-4-propylphenol and 1,2-dimethoxy-4-propylbenzene, The hydrogenation of 2-methoxy-4-propylphenol and 1,2-dimethoxy-4-propylbenzene is accompanied by some hydrogenolysis and removal of the OMe group.

URL<Go to ISI>://A1997WY10200002