Dimethyltins

Physica.1 Properties. Physical properties of some typical diorganotin compounds are shown in Table 6. The diorganotin chlorides, bromides, and iodides are soluble in many organic solvents and, except for dimethyltin dichloride, are insoluble in water. 

Itnidazole-2-carbaldehyde thiosemicarbazone forms the 5-chelate complex 21 upon reaction with dimethyltin oxide (00JCS(D)2267). 

In a rather different type of process, oligomeric dimethyltin and tris(dimethyltin sulfide) react together to give the dithiatristannacy-clopentane (255). 

Dimethyltin bis(fluorosulfonate), Me2Sn(S03F)2, has a similar, polymeric structure (373). 

Dimethyltin dichloride has a similar chain structure (375). In diethyltin diiodide (374), dimethyltin diisothiocyanate (376, 377), and di-chloro bis(chloromethyl)stannane (378), however, the distorted, trans-RgSnX geometry of each tin atom is completed by two bridging bonds involving the halogen or pseudohalogen atoms on the same, neighboring molecule. 

Dimethyltin dichloride is used in the glass industry as an alternative to stannic chloride for coating glass with a thin film of stannic oxide 562). The dialkyltin compound vapor is brought into contact with the glass surface at temperatures of 500-600°C, where decomposition and oxidation occurs. 

Dimethyltin dichloride (hRf 15-20), trimethyltin chloride (h/ f 55-60), dibutyltin dichloride (h/ f 70-75) and tributyltin methoxide (h/ f 80-85) appeared in long-wavelength UV light (X = 365 nm) as yellow fluorescent chromatogram zones on a dark background. The detection limits (calculated as Sn) lay between 5 and 10 ng (dimethyltin dichloride, dibutyltin dichloride, tributyltin methoxide) and 50 ng (trimethyltin chloride) substance per chromatogram zone. 

Fig. 1 Fluorescence scan of a chromatogram track with 100 ng substance (calculated as Sn) each per chromatogram zone 1 = dimethyltin dichloride, 2 = trimethyltin chloride, 3 = dibutyltin dichloride, 4 = tributyltin methoxide.

Neurotoxicity is the major end-point for the methyl-tins, with a NOAEL of approximately 0.6 mg/kg body weight based on neuropathology for dimethyltin limited data for monomethyltin preclude the derivation of a NOAEL. No neurotoxicity was found with dibutyltin or mono- and dioctyltins no information is available for monobutyltin. 

Developmental toxicity is shown by the disubstituted methyl-, butyl-, and octyltins, but not by the corresponding monosubstituted compounds. The major reported effect is teratogenicity, with effects on fetuses shown at doses close to maternally toxic ones in most cases. NOAELs for dimethyltin, dibutyltin, and dioctyltin are 10 (10), 2.5 (1.0), and 45 (30) mg/kg body weight per day for teratogenicity (maternal toxicity NOAELs in parentheses). 

Reliable lifetime TDI values cannot be derived, since long-term studies at the appropriate doses and in the appropriate species are not available. Medium-term exposure TDIs for the estimation of risk were estimated (as the chlorides) as 0.0012 mg/kg body weight for monomethyltin and dimethyltin based on neurotoxicity, 0.003 mg/kg body weight for dibutyltin based on immunotoxicity, and 0.002 mg/kg body weight for dioctyltin, also based on immunotoxicity. No reliable TDI could be derived for monobutyltin or monooctyltin. 

Monomethyltin trichloride Dimethyltin dichloride Monobutyltin trichloride Dibutyltin dichloride Monooctyltin trichloride Dioctyltin dichloride... 

Dimethyltin (EHMA) 45% degradation in 28 days 58% in 39 days Readily, but failing 10-day window (2002b,d,h,j,l,m)... 

Dimethyltin dichloride 3% degradation in 35 days Not readily biodegradable g)... 

Much lo wer concentrations of mono- and dimethyltin were also measured. 

Similar calculations have been undertaken for the mono- and dimethyltin compounds and the mono- and dioctyltin compounds. All of the calculations and input data used are the same (in terms of quantities used at a site, losses to air, and percentages lost to wastewater). It is assumed that the stabilizer compounds contained either 50% each of monomethyltin trichloride and dimethyltin dichloride (for the methyltins) or 50% each of monooctyltin trichloride and dioctyltin dichloride (for the octyltin compounds). 

There are very limited studies on absorption of organotins. Noland et al. (1983) formd maximum blood concentrations of dimethyltin after dosing pregnant rats... 

MMT, monomethyltin DMT, dimethyltin MBT, monobutyltin DBT, dibutyltin TBT, tributyltin MOT, monooctyltin DOT, dioctyltin... 

MMT, monomethyltin DMT, dimethyltin MBT, monobutyltin DBT, dibutyltin TBT, tributyltin MOT, monooctyltin DOT, dioctyltin Exposure via house dust (which has been measured as containing organotins) was also considered it is likely that inhalation exposure indoors includes house dust, which picks up leached organotins from vinyl flooring. 

Dermal exposure of rats to doses of dimethyltin dichloride at 80 mg/kg body weight produced dermal necrosis with the formation of black scars the same dose of dibutyltin dichloride produced little surface damage to the skin together with subcutaneous oedema. Dioctyltin dichloride produced no skin lesions (Barnes Stoner,... 

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