Date of Award

5-2001

Level of Access Assigned by Author

Open-Access Thesis

Degree Name

Master of Science (MS)

Department

Chemistry

Advisor

Barbara J.W. Cole

Second Committee Member

Raymond C. Fort, Jr.

Third Committee Member

Adriaan R.P. van Heiningen

Abstract

Some thiols have been shown to be efficient in both bleaching and stabilizing the brightness of mechanical pulps. Two thiols, thioglycerol and glycol dimercaptoacetate, have received considerable attention due to their photostabilization effects. Their reactions with 1,4-benzoquinone, a model lignin compound, were investigated. In the first part of this study, reaction products were isolated using preparative HPLC and were fully characterized using GC-MS as well as l3C-NMR Both thiols were found to undergo Michael addition with the model quinone (in methanol) to yield a substituted hydroquinone. Further reaction with excess quinone in the presence of UVlight facilitated subsequent redox reactions producing darkly colored substituted quinones. Another part of this research examined the reaction of the substituted hydroquinones with lightly bleached aspen CTMP. The nearly colorless substituted hydroquinones were applied to the test papers and irradiated for several hours. The brightness pads darkened quickly, suggesting redox chemistry that was similar to the reaction with 1,4-benzoquinone. An extraction was performed and the products examined with W-Visible spectrometry. This research fbther supported the hypothesis that these thiols react with chromophoric quinoid structures in lignin resulting initially in a bleaching effect. Subsequent redox reactions produce highly colored materials leading to a pulp that is ultimately darker than untreated pulp.

Download

Share