1-alkoxymethyl-X-dimethylaminopyridinium-base ionic liquids in wood preservation

The following pyridinium-based ionic liquids (ILs) have been successfully tested as components of potential wood preservatives: 1-alkoxymethyl-3-dimethylaminopyridinium chlorides, 1-alkoxymethyl-4-dimethylaminopyridinium chlorides, 1-alkoxymethyl-3-dimethylaminopyridinium acesulfamates and 1-alkoxymethyl-4-dimethylanninopyridinium acesulfamates. These ILs are new biocides that penetrate well into wood. The tested pyridinium ILs with an alkoxymethyl substituent, consisting of 8, 9 or 10 carbon atoms, exhibited fungicidal activity against the basidionnycetes Coniophora puteana and Trametes versicolor and the blue-stain fungus Sclerophoma pityophila. The effective and lethal doses were measured by the agar-plate method and the toxic values, before and after leaching according to EN 84, were determined based on the EN 113 block method. The doses and toxic values of tested 1-decyloxymethyl-4-dimethylaminopyridinium chloride and acesulfamate were comparable with benzalkonium chloride and didecyldimethylammonium chloride. The ILs tested were largely unleachable from wood by water. The mechanical properties of wood treated with the former two ILs were lower than natural wood. Wood treated with the chloride and acesulfamate was, however, characterized by lower absorption of free water than the control wood. Only in the case of treatment with acesulfamate was the hygroscopicity of treated wood distinctly lower than that of control wood. The durability of wood was increased by 1-decyloxymethyl-4-dimethylaminopyriclinium chloride and acesulfamate.