FUNGAL RESISTANCE OF LOBLOLLY-PINE REACTED WITH PARA-TOLUENE SULFONYL CHLORIDE OR ISOCYANATE

Loblolly pine sapwood reacted with para-toluene sulfonyl chloride or isocyanate to form bonded toluene sulfonate or toluene sulfonyl carbamate in situ resisted attack by the brown-rot fungus Gloeophyllum trabeum. Wood reacted with para-toluene sulfonyl chloride to 9.1% chemical weight gain (59 mmol/100 g wood) and para-toluene sulfonyl isocyanate to 7.5% chemical weight gain (56 mmol/100 g wood) had 3.8 and 2.7% weight losses, respectively, in a standard 12-week soil-block fungal decay test. The tosylated wood lost 23% of the tosyl group in the decay test, whereas the wood modified with tosyl carbamate lost 8.4% of the tosyl carbamoyl group. The greater leach resistance of wood reacted with para-toluene sulfonyl isocyanate may indicate that the stability of the bond between fungicidal groups and wood plays a more important role than the hydrophobicity of fungicidal groups in the permanence of the fungicidal groups in modified wood.