Aleksandra Kropacz

A new group of quaternary ammonium ionic liquids with azolate (benzotriazolate, 1,2,4-triazolate, 4-nitroimidazolate, 2-methyl-4-nitroimidazolate) anions was prepared and characterized. The synthetic method employed was easy and quick, and required a polar solvent. The obtained ionic liquids were tested as anti-microbial and anti-fungal plant protection agents. Additionally, the surface-active properties and the phytotoxicity of the quaternary ammonium azolates were also studied. These clearly defined ionic liquids were found to be very effective anti-bacterial and anti-fungal agents.

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-dimethylaminopyridinium 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 basidiomycetes 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-dimethylaminopyridinium chloride and acesulfamate.

In this study ionic liquids (3-alkoxymethyl-1-methylimidazolium tetrafluoroborates and hexafluoro-phosphates) are successfully used for wood preservation. These liquids are new biocides as well as new solvents which penetrate wood well. The prepared ionic liquids with an alkoxymethyl substituent, which consisted of 7, 8 or 9 carbon atoms, exhibited fungicidal activity against Coniophora puteana (Schum.: Fr.) Karst., Trametes versicolor (L.: Fr.) Pilát and Sclerophoma pityophila (Corda) v. Höhn. The effective and lethal doses were measured by the agar-plate method. In their activity against wood degrading fungi, ionic liquids such as 1-methyl-3-octyloxy-methylimidazolium and 1-methyl-3-nonyloxymethylimidazolium tetrafluoroborates were comparable with commercially available benzalkonium chloride and didecyldimethylammonium chloride. Ionic liquids both with and without DDAC penetrated into Scots pine wood very well.