The three most widely used preservative compounds are Chromated Copper Arsenate (CCA), Pentachlorophenol (PCP) and Creosote (which is a mixture of phenolic compounds). These preservatives are very effective but their long-term future use is questionable because of environmental concerns. These concerns have resulted in restrictions in usage and in some countries a ban on their use as wood preservatives. Consequently, there is a need for new wood preservative chemicals that have low mammalian toxicity and are environmentally friendly. In addition to phenolic compounds, sulfur compounds are extensively used in agriculture as herbicides and insecticides. Therefore, it was surmised that compounds containing both phenol and sulfur moieties would have potential as wood preservatives. In order to provide permanency, oligomeric or polymeric forms of these compounds are highly desirable in order to prevent preservative loss during treatment as well as from wood either by volatilization and / or by leaching. The excellent performance properties of the polymeric alkylphenol polysulfides as environmentally-benign wood preservative compounds to protect wood from wood decay fungi will be exemplified in this article by a representative compound currently under research and development - Polymeric Xylenol Tetrasulfide (PXTS). Monomeric phenol/ sulfur compounds have applications as vulcanizing agents (Wolf, 1946), as anti-oxidants for rubbers and plastics (Anon. 1986), as antibacterial additives in the form of bithionol or fenticlor and trihalogenated phenol for paints and wooden articles (Anon. 1990a), as delayed release antibacterial agents comprised of an inclusion compound of hinokitiol with a bisphenol (Anon. 1990b), and as bactericidal and fungicidal composition prepared from a mixture of chlorhexidine, trihalogenated phenols and phenylphenols ( Anon. 1990c). In addition, Asakura et al. (1989) reported on the anti-oxidant effect and antimicrobial activity of phenolic sulfides wherein the sulfur is attached to the alkyl side chain. Michael addition and radical addition reactions of ethanethiol and ethanedithiol with o-, m- and p-vinylphenol were used to prepare these phenolic sulfides. Gabler et al. (1974) reported that certain bisphenol compounds linked together with a thio bridge are highly active fungicides having a broad spectrum of activity.

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