Organic Tin

Tin, having valence of +2 and +4, forms staimous (tin(II)) compounds and stannic (tin(IV)) compounds. Tin compounds include inorganic tin(II) and tin(IV) compounds complex stannites, MSnX., and staimates, M2SnX, and coordination complexes, organic tin salts where the tin is not bonded through carbon, and organotin compounds, which contain one-to-four carbon atoms bonded direcdy to tin. 

Table 9. Physical Properties of Organic Tin Salts of Minor Commercial Importance...

Occupational Health Guidelinesfor Organic Tin Compounds as Tin), U.S. Department of Labor, Occupational Safety and Health Administration, Washington, D.C., 1978. 

Polydimethyl siloxane is of moderately high molecular weight. The siHcone is a viscous Hquid. CoUoidal siHca or micronized metal oxides, 5—10 p.m particle size, are added to prepare a paste that is mixed with a tetraalkyl siHcate containing 50% ethoxy groups, eg, commonly tetraethyl orthosiHcate, and 1—2% of an organic tin activator. This type of catalyst has a limited shelf life because of oxidation. 

Boron, as barium metaborate, is marketed as a mildew preventative for paints (273). Borax is used as a wood preservative, and an organic boron, 2,2 -(l-methyltrimethylenedioxy)-bis(4,4,6-trimethyl)-l,3,2-dioxaborinane (Biobor JF) [14697-50-80] is a biocide for jet fuel (274). Whereas tin metal is used to coat steel cans used as food containers, organic tin in the form of tributyl tin compounds have proven to be powerfiil antimicrobials, and have found use in antifouHng coatings for ship bottoms, paints, and wood preservatives (275). 

DEPA (2002) Organic tin compounds in consumer products. Summary in English of DEPA (2000a) and DEPA (2000b), personal communication received 14 February 2002 from Danish Environmental Protection Agency. 

Metals that are soft Lewis acids, for example cadmium, mercury, and lead, are extremely hazardous to living organisms. Tin, in contrast, is not. One reason is that tin oxide is highly insoluble, so tin seldom is found at measurable levels in aqueous solution. Perhaps more important, the toxic metals generally act by binding to sulfur in essential enz Tnes. Tin is a harder Lewis acid than the other heavy metals, so it has a lower affinity for sulfur, a relatively soft Lewis base. 

Currently available CRMs Calibrants are available for TBT (very evident, as TBT is an anthropogenic contaminant) and for a number of other organic tin compounds. There is also an interesting choice of environmental CRMs (sediment and mussel tissue) certified for TBT content. 

The organic tin compound OTC (heat stabiliser) was extracted from PVC by US extraction and analysed by UV spectrophotometry [55]. 

Allylations, allenylations, and propargylations of carbonyl compounds in aqueous media can also be carried out with preformed organic tin reagent, rather than the use of metals.86,87,88 For example, the allylation reaction of a wide variety of carbonyl compounds with tetraal-lyltin was successfully carried out in aqueous media by using scandium trifluoromethanesulfonate (scandium triflate) as a catalyst (Eq. 8.40).89 A phase-transfer catalyst (PTC) was found to help the allylation mediated by tin at room temperature without any other assistance.90... 

The classical route to synthesize organic tin(II) compounds is the thermolysis or photolysis of tetravalent tin compounds. The driving force of these reactions may be either weak tin-tin bonds or the formation of stable compounds besides the desired... 

The analytical response of inorganic and organic tin compounds of formula R SnX 4 was studied for direct hydride generation and measurement with a non-dispersive AFD (atomic fluorescense detector). Tributyltin and phenyltin compounds gave unsatisfactory results. This was corrected by warming the sample with a dilute Br2-HN03 solution37. 

Tin is comparable in its toxicological behavior to lead and mercury. Bivalent tin compounds generally are more toxic than the tetravalent compounds. Furthermore, organic tin compounds are more toxic than inorganic ones and the trialkyl analogs (triethyltin, trimethyltin, tributyltin) are the most toxic. As the number of carbon atoms attached to tin increases, the toxicity of the organic tin compounds rapidly declines9,77. 

Organic tin compounds have the effects of neurotoxicity, immunotoxicity and genotoxicity however, studies on the genotoxicity of organic tin compounds are comparatively scarce. It is important to study the genotoxicity of organic tin compounds, because those that show genotoxicity have the potency to induce mutations or cancer. 

Hamasaki and coworkers87 investigated the genotoxicity of 14 organic tin compounds (methyl-, butyl- and phenyltins) and inorganic tin (SnCU) on Escherichia coli and on Bacillus subtilis. Dibutyltin dichloride, tributyltin chloride, tributyltin chloride, bis(tributyl-tin)oxide, dimethyltin dichloride and trimethyltin chloride were all found to be genotoxic. 

Tin is shown to be methylated by organisms and other environmental factors. Organic tin compounds are much more toxic than the inorganic ones. This increase in toxicity due, e.g., to methylation is attributable to the increasing membrane permeability of the methylated metal compounds and to the remaining sensibility to react with sulfhydryl groups of proteins, especially of enzyme proteins. 

Organic tin compounds have been used in various fields, such as antifouling paints, stabilizers of PVC, agricultural chemicals and so on, while lately anticancer and antitumor activities of organic tin compounds are also studied38,39. 

Lethal and sublethal effects of inorganic and organic tin compounds in ambient medium to selected species of aquatic organisms... 

Table 8.8 Lethal and Sublethal Effects of Inorganic and Organic Tin Compounds in Ambient Medium...

Inorganic tin compounds and some heterocyclic organic tin compounds are of low toxicologic risk to mammals (Table 8.11), due largely to their low solubility, poor absorption, low tissue accu-... 

The development of sensitive and rapid analytical schemes for the extraction and separation of inorganic tin and organic tin compounds and their chemical speciation products from water, sediments, and biological materials (WHO 1980 Reuhl and Cranmer 1984 Hall and Pinkney 1985 Laughlin and Linden 1985 Thompson et al. 1985 Blunden and Chapman 1986 USPHS 1992). 

Lead and organic lead compounds Organic tin compounds... 

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