Dioctyltin

Of the large volume of tin compounds reported in the Hterature, possibly only ca 100 are commercially important. The most commercially significant inorganic compounds include stannic chloride, stannic oxide, potassium staimate, sodium staimate, staimous chloride, stannous fluoride, stannous fluoroborate, stannous oxide, stannous pyrophosphate, stannous sulfate, stannous 2-ethyUiexanoate, and stannous oxalate. Also important are organotins of the dimethyl tin, dibutyltin, tributyltin, dioctyltin, triphenyl tin, and tricyclohexyltin families. 

Dibutyltin and dioctyltin diacetate, dilaurate, and di-(2-ethylhexanoate) are used as catalysts for the curing of room-temperature-vulcanized (RTV) sihcone elastomers to produce flexible siUcone mbbers used as sealing compounds, insulators, and in a wide variety of other appHcations. Diorganotin carboxylates also catalyze the curing of thermosetting siHcone resins, which are widely used in paper-release coatings. 

In Germany, the following monoorganotins alone or in mixtures are also approved for this use butylthiostannoic acid anhydride with either dioctyltin compounds or 2-carbobutoxyethyltin compounds, 2-carbobutoxyethyltin tris(isooctylmercaptoacetate) alone or mixed with its dicounterpart, monomethyltin tris(isooctylmercaptoacetate) [56225-49-1] plus its dicounterpart in a 24 76 wt % ratio, and monooctyl tin tris [alkyl (C q—isooctyl) mercaptoacid esters] with thek dicounterparts. 

Detection and result The chromatogram was freed from mobile phase (heated to 110°C for 30 min) and then exposed to bromine vapor for 1 h in a chamber, after blowing off excess bromine from the layer it was immersed for 1 s in the reagent solution. On drying in air dibutyltin dilaurate hRf 25 — 30), dibutyltin dichloride (kR( 25 — 30), dioctyltin oxide (hR( 40), tributyltin oxide (hRf 80), tributyltin chloride (hRf 80) and tetrabutyltin (hRf 85-90) produced persistent blue zones on a yellow ochre background (Fig. 1). 

Fig. 1 Chromatogram of organotin compounds. Dibutyltin dilaurate (1), dibutyltin dichloride (2), dioctyltin oxide (3), tributyltin oxide (4), tributyltin chloride (5), tetrabutyltin (6).

Dimethylphenol, synthesis of, 383 /V,/V-Dimorpholinodicthyl ether (DMDEE), 225, 230 Dinitrile-diamine polyamides, 158 Dioctyltin dilaurate, 232 Diol-functionahzed telechelic polymers, 457... 

There are very limited data on the kinetics and metabolism of organotins in laboratory mammals. A widespread distribution of organotins throughout body tissues has been observed. Transplacental transfer seems to occur, whereas transfer across the blood-brain barrier is limited, since brain levels are usually low. The only compound for which data are available on metabolites is dibutyltin, which has butyl(3-hydroxybutyl)tin as its major metabolite. Limited information suggests quite rapid metabolism and elimination, with half-lives of several days. Much of an oral dose of dioctyltin was eliminated in the faeces, with the remainder in urine. 

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. 

NOAELs for mono- and dioctyltin have been determined to be 0.87 and 0.23 mg/kg body weight per day, respectively, although the value for monooctyltin is an estimate, because the study was performed using a mixture. Other information suggests that dioctyltin is the more immrmotoxic of the two compormds. 

Tributyltin is well established as an aromatase inhibitor, and dibutyltin appears to have some potency also (exact characterization of the endocrine disrupting capacity of dibutyltin alone is difficult because of the presence of tributyltin as an impurity). Monobutyltin and mono- and dioctyltins have no aromatase inhibiting capacity in in vitro tests. No data are available for this end-point for the methyltins. 

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... 

The associated baking paper is supplied by two companies, which use dioctyltin-based stabilizers exclusively. Thus, dioctyltin-catalysed silicone-coated... 

Organotin compounds such as monobutyltin oxide, the main substance used, accounting for 70% of consumption, dibutyltin oxide, monooctyltin oxide, and dioctyltin oxide are used in certain esterification and transesterification reactions, at concentrations between 0.001% and 0.5% by weight. They are used in the production of substances such as phthalates, polyesters, alkyd resins, fatty acid esters, and adipates and in trans-esterifications. These substances are in turn used as plasticizers, synthetic lubricants, and coatings. Organo-tins are used as catalysts to reduce the formation of unwanted by-products and also provide the required colour properties (ETICA, 2002). 

In addition, data are available for a study on the degradation of dimethyl-, dibutyl-, and dioctyltin chlorides in soil (Terytze et al, 2000). It is of note that the results of the degradation testing indicate that the diorganotin compounds are partially degraded to the corresponding monosubstituted compounds by way of example, dioctyltin concentrations were observed to decrease from 40 to 12 ng/1 over a 3-month period while the monooctyltin concentration stayed relatively constant at around 2 ng/1. It is therefore likely that only a fraction of dioctyltin decayed to monooctyltin and/or the... 

Dioctyltin (EHMA) 36% degradation in 28 days 49% in 74 days Readily, but failing 10-day window ... 

Dioctyltin dichloride 0% degradation In 39 days No biodegradation observed ... 

Dioctyltin oxide 2% degradation In 31 days Not readily biodegradable ... 

In a recent Swedish survey on effluents from sewage treatment plants, small amounts of dioctyltin substances were occasionally found in the sewage sludge, but no dioctyltin substances were detected in the water phase (Walterson et al, 1993). 

Value for dioctyltin dichloride drawn from Japanese Ministry of International Trade and Industry (1992) values for butyltins are from Tsuda et al. (1986, 1988). 

A higher concentration of dioctyltin in sewage sludge of 0.56 mg/kg as the chloride is reported by Summer et al. (2003). Thus, the maximum reported concentrations for the individual compounds are as follows ... 

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). 

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. 

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