Chemical modification of wood. II. Use of trifluoroacetic acid as catalyst for the acetylation of wood

Sapwood lengths of Ponderosa pine ( Pinus ponderosa ) have been acetylated, without loss of strength or discoloration, at temperatures of 25–45° to 16–30% acetyl with acetic anhydride, using trifluoroacetic acid and magnesium perchlorate as combined synergistic catalysts. When matched samples were acetylated to similar weight gains and acetyl contents by low‐ and high‐temperature methods, the former method resulted in permanent shrinkage of the wood blocks and a small reduction (∼20%) in swelling property, whilst the latter method, in corroboration of published data, caused permanent bulking and a 75% reduction in swelling property.