Tributyltin

''"TBT" redirects here. For the high school located in Tampa, Florida, see Tampa Bay Technical High School.''

Tributyltin (TBT, Bu3SnH) is a trialkyl organotin compound. Tributyltin compounds are a subgroup of the trialkyl organotin family of compounds. They are the main active ingredients in biocides used to control a broad spectrum of organisms. Uses include wood preservation and preservation, antifouling of boats (in marine paints), antifungal action in textiles and industrial water systems, such as cooling tower and refrigeration water systems, wood pulp and paper mill systems, and breweries. It is also used for control of schistosomiasis in various parts of the world. Tributyltin oxide is the widely used compound in TBT containing commercial products. TBT compounds are considered as toxic chemicals which have negative effects on human and environment. Tributyltin compounds are moderately to highly persistent organic pollutants. One common example is leaching of TBT from marine paints into the aquatic environment, causing irreversible damage to the aquatic life.

TBT is harmful to some marine organisms, including the dog whelk. TBT causes dog whelks to suffer from imposex: females develop male sexual characteristics such as a penis. This causes them to become infertile or even die. In severe cases males can develop egg sacs.

Tributyltin, dibutyltin and toxicity to marine mammals
Studies have shown that wild, dead sea otters (Enhydra lutra) and stranded bottlenose dolphins can have extremely high levels of tributyltin in their livers. Both tributyltin and dibutyltin, a metabolite byproduct, cause immunosuppresion, leading to secondary infections. This was supported by the finding that otters dying of infectious causes tend to have higher levels of tissue butyltins than those dying of trauma or other causes. (See Kannan et al. 1998. Butyltin residues in Southern sea otters (Enhydra lutris nereis) found dead along California coastal waters. Environ. Sci. Technol. 32:1169-1175).

Tributyltin toxicity to marine invertebrates
TBT is extremely toxic to molluscs. In the case of bivalve larvae, the effective concentration (EC50) of TBT is 1000 times lower than that of any other toxic compound introduced into the marine environment (see Fig.15 on p. 134 in: His et al. 1999. The assessment of marine pollution – bioassays with marine embryos and larvae. Adv Mar Biol 37:3-178). TBT also causes imposex in marine gastropods and is probably responsible for reductions in their populations in zones with important ship traffic.

Use in organic synthesis
Tributyltin is a useful reagent in organic synthesis. Combined with azobisisobutylonitrile, tributyltin generates radicals by removing a hydrogen atom from the molecule of interest.

Tributylzinn TBT Tributylétain Tributyltin