Esterification of wood with unsaturated carboxylic acids. I. : Preparation of several wood-esters by the TFAA method

Abstract

無水トリフルオロ酢酸法を用いて, 木材の不飽和カルボン酸エステルを調製し, 木材の改質を試みた。エステル化木材を赤外線吸収, X線回折, 吸湿およびけん化法で検討し, 次の結果を得た。1) エステル化度は酸の種類により大きい差異があった。これは主として酸のpKaで説明されたが, 分子構造 (アグリル酸系列でのメチル基とカルボキシル基の相互位置, 二塩基酸でのシスとトランス配置など) も影響した。2) 反応後, トリフルオロ酢酸を除くことは意外に困難であった。3) 硫酸の少量添加はエステル化を促進したが, 木材の分解ももたらした。4) 木材をエチレンジアミンで前処理すると, わずかのエステル化で木材の非晶化が行なえる結果も示された。

In order to prepare esterified wood which would possess improved properties for many end uses, beech wood meal was treated with carboxylic acids, using the trifluoroacetic anhydride "impelling" method. The esterified wood was examined by several analytical methods. Monocarboxylic acids reacted with wood in different degrees and more readily than di- and tribasic acids, while removal of very labile trifluoroacetyl groups was incomplete unexpectedly. Different degrees of esterification were well explained in terms of pKa and steric configuration of acids used. Additional sulfuric acid catalyst brought about increasing esterification in many cases, but weight increase was diminished by its strongly degradative action on wood in some cases. The ordered region of wood was easily destroyed by less esterification, combined with EDA-pre-treatment on wood.