Organotin chemistry
Organotin compounds ( organotin compounds, organotin compounds ) is the collective name for organometallic compounds with one or more tin-carbon bonds, which can be described by the general formula RnSnXm. Here, " R" is a hydrocarbon group and X is a group of any other, such as a halogen or a hydroxyl group (OH). Organotin compounds are used as biocides among other things, in wood preservatives, plastics additives and catalysts. From the late 1990s produced worldwide annually 40,000 tons of organotin compounds were approximately
- 76% as stabilizers for polyvinyl chloride ( PVC),
- 10% as biocides in marine paints
- 8% as agricultural fungicides and
- 5% as a catalyst in the production of polyurethane foams and silicone
Be used. However, the consumption of organotin compounds due to their ecotoxicity is declining. For example, the tributyltin previously used as an antifouling agent in marine paints ( TBTO ) in many countries due to its high ecotoxicity (limited) is prohibited.
Organotin compounds are found worldwide in the environment, with a portion formed by natural processes ( biomethylation ), the other passes through the production and use in the environment. Organotin compounds were, inter alia, detected in house dust and harbor sediments.
Toxic properties
The toxic properties of organotin compounds vary with the number and nature of the organic substituents ( R), but can be simplified as follows summarized for industrially used materials:
- Tetra- organo-tin compounds, R 4 Sn, are very stable, have virtually no biocidal activity and are virtually non-toxic. However, they can be converted by metabolic processes in an organism slowly decompose into toxic triorganotin compounds or.
- Tri - organotin compounds, R3SnX, make the most toxic group of organotin compounds dar. trialkyl tin compounds with linear organic radical can not be used as agricultural biocides due to their high toxicity plants ( phytotoxicity ). The group of tri- organotin compounds include tributyltin, which is the biocidal ingredient in antifouling paints for ship hulls, and tributyltin oxide ( TBTO ) and tributyltin chloride ( TBTC ).
- Di - organo-tin compounds, R2SnX2 have, with the exception of diphenyl, only a low antibacterial activity and toxic.
- Mono- organotin compounds which are not RSnX3 biocide, and have only a low toxicity to mammals.