Author
HOSOYA, TAKASHI - University Of Natural Resources & Applied Life Sciences - Austria | |
FRENCH, ALFRED - Retired ARS Employee | |
ROSENAU, THOMAS - University Of Natural Resources & Applied Life Sciences - Austria |
Submitted to: Journal of Organic Chemistry
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 3/25/2013 Publication Date: 5/20/2013 Citation: Hosoya, T., French, A.D., Rosenau, T. 2013. Chemistry of 5,8-dihydroxy-[1,4]-benzoquinone, a key chromophore in aged cellulosics. Journal of Organic Chemistry. 10:309-315. Interpretive Summary: Cotton or linen fabrics and paper, as well as other items composed chiefly of cellulose, tend to change to a yellow or brown color as they age. The change in color is usually accompanied by increased brittleness and loss of strength, as well. A cause of these phenomena is thought to be the formation of chemical compounds (chromophores) that originate in the individual glucose units of the cellulose which consists of many glucose residues connected together. In the present work, many aspects of the structure and chemistry of an important chromophore, 2,5-dihydroxy benzoquinone are brought together along with new results from computational quantum mechanics studies to obtain new understanding of the various reaction mechanisms and potential ways to stop, or slow, the deterioration of items made from cellulose. Current attempts to change the color are by bleaching, for example, are largely futile because the benzoquinone structure is readily re-oxidized to the dihydroxy benzoquinone, a chromophore that is visible at the parts per billion level. Other chemical remedies are discussed. Technical Abstract: 2,5-Dihydroxy-[1,4]-benzoquione is one of the three key chromophores found in aged cellulosics. Knowledge of the general reactivity and chemistry of this compound is helpful for a better understanding of cellulose aging and yellowing as well as bleaching of cellulosic materials - processes which also have considerable economic importance. This paper reviews the reactions reported for 2,5-dihydroxy-[1,4]-benzoquinone, from the viewpoints of both synthesis and general reactivity. The exhibits a rich chemistry because of the presence of both carbonyl and enol motifs, and is able to undergo both nucleophilic and electrophilic substitions. Other major pathways are the condensation with amines, derivatization of the hydroxyl groups, reductions and oxidative degradation. |