Wood preservation by a mixed anhydride treatment: Using simple models of polymeric wood compounds

IRG/WP 08-30457

F Lyon, M-F Thevenon, A Pizzi, G Tondi, A Despres, J Gril, S Rigolet

Treatment of wood by a mixed aceto/oleic (or other fatty acid residue) anhydride promoted as a safe and environment friendly wood preservation system has been examined quantitatively by liquid phase 13C NMR and solid phase MAS-DEC (proton decoupling) 13C NMR through all its different stages to determine which reactions occur with simple model compounds of the polymeric constituents of wood. The preparation of the mixed aceto/oleic anhydride under different conditions has been followed too. The anhydride forms but its percentage yield was found to be of the order of only 30%. The mix composed of unreacted acetic anhydride, the mixed aceto/oleic anhydride, and great proportions of free acetic acid and free oleic acid which is used for wood preservation yields acetylation of the lignin model compound (i) by reaction of the acetic anhydride with it and (ii) by reaction of the acetic part of the mixed anhydride. In this reaction the whole mixed anhydride is consumed and nothing of it is left. The oleic part of the mixed anhydride apparently is not able to form esters on lignin being far less reactive than the acetic part. Carbohydrates appears much less readily esterified, being polar enough to be repellent to the oleic residue, some acetylation occurring and some traces, and no more than traces, of carbohydrates oleic acid ester occurring too under some conditions. This system of treatment through a mixed anhydride boils down to being just an acetylation with acetic anhydride, mixed with some oleic acid as water repellent, both already known processes.

Keywords: wood treatment, mixed anhydride, fatty acids, water repellents, dimensional stabilization

Conference: 08-05-25/29, Istanbul, Turkey

Download document (703 kb)
free for the members of IRG. Available if purchased.

Purchase this document