Reactions of Some Monoterpens with Chlorine Dioxide, 1996 International Pulp Bleaching Conference Proceedings

Douglas W. Reeve, Fred Xi, Denise H.Y. Tong, and A. Bruce McKague

University of Toronto

Most of the monoterpenes found in the softwood are recovered with other volatile substances as crude turpentine during the digestion of wood. However, since monoterpenes are hydrocarbons and are immiscible with water, they are difficult to completely remove from pulp before bleaching. The residual monoterpenes entering the bleach plant may react with chlorine-containing products bleaching agents to form chlorinated products. The purpose of this work is to determine the chemical structures of products from reactions of several monoterpenes with chlorine dioxide. In the first stage of research, pure a-pinene and p-cymene were reacted with aqueous chlorine dioxide at 75 °C for 3.5 h. The products were separated and analyzed by gas chromatography mass spectrometry, and NMR spectrometry. 2-chlorobornane-6-one was identified as the major product from the reaction of a-pinene with chlorine dioxide. 9-chloro-p-cymen-8-ol was the major product from reaction of p-cymene with chlorine dioxide. Minor amounts of other mono- and dichlorinated reaction products were also found. In the second part of the work, softwood kraft pulp was impregenated with and p-cymene and bleached with chlorine dioxide 9-chloro-p-cymen-8-ol was not found in the D-stage filtrate. These studies show that even with aggressive treatment, the main chlorinated products from the reaction of monoterpenes with chlorine dioxide are...