Dibutyltin dibromide

Synthesis of bromoethane (ethane + HBr) and of dibutyltin dibromide (bromobutane + Sn). Other halogenation reactions such as bromina-tion of p-xylene to tetrabromoxylenes is of importance as an efficient fire extinguishing agent for plastics. 

Lethality in mice was observed following single or repeated daily exposures to a butyltin mixture (81.2% tributyltin bromide and 3.7% dibutyltin dibromide) together with other unidentified compounds (15.1%) (Igarashi 1959). The concentration was 5.65 mgtin/m (1.16 ppm) as the butyltin mixture for different durations of exposure. The tributyltin bromide concentration was 1.1 ppm and that for dibutyltin bromide was 0.06 ppm. For a 2-day, 8-hour/day exposure, approximately 80%-90% of the exposed mice died. Despite the observation of other signs of toxicity (see Section 2.2.1.2) the exposure of the mice to multiple compounds confound the interpretation of the data. 

Rats were exposed to a nominal concentration of 2 mg tin/m (0.41 ppm) as a mixture of tributyltin bromide (81.2%) with other compounds such as dibutyltin dibromide in acute- and intermediate-duration exposures to assess reproductive effects (Iwamoto 1960). This tin exposure was equivalent to 0.39 ppm tributyltin bromide and 0.02 ppm dibutyltin bromide. Pregnancy rates were markedly reduced after 4 weeks to 3 months of exposure however, at least partial reversibility of the effects was seen when exposure was discontinued. Histopathological evaluations were made... 

Tributyltin bromide or iodide and dibutyltin dibromide or diiodide can be prepared from the corresponding chlorides by reaction with alkyl bromides or iodides in the presence of a tetrabutylammonium halide catalyst. It is suggested that the reaction involves the coordination of halide ion to the tin, then nucleophilic substitution by the chloride ligand at the carbon centre (equations 11-18,11-19 and 11-20).35... 

Radiation-Chemical Synthesis of Dihutyltin dibromide. The pilot plant used for the radiation-chemical synthesis of dibutyltin dibromide (DBTDB) has been described (7). The materials used were n-butyl... 

Similarly, known mixtures of the component halides, e.g. butyltin tribromide, dibutyltin dibromide and tributyltin monobromide, were made up, and plots were constructed of peak heights and areas against weight concentrations in the mixture. These calibration curves were sufficient to enable each component of the mixture to be determined quantitatively. Peak areas were measured as the products of peak height and width at half peak height (Scott and Grant ). 

It was found that in this method the Grignard reaction is indeed quantitative and that no loss of sample occurred during other steps in the sample preparation procedure. Nevertheless, it is seen in the analyses of synthetic mixtures shown in Table 111 that large differences between the added and observed quantities occur of all the components excluding the dibutyltin dibromide in Standards 1 and 2. By converting the weight percent values to mole percentages, as in Table 112 the reason for these discrepancies becomes apparent. 

Dibutyltin dibromide is the only material that does not take part in this redistribution reaction. The data obtained for this material are more indicative of the accuracy of the method and the observed values are within 1% of the actual percentage in every case. Apparently, the accuracy of the method is at least as good as the precision with which the calibration factors for the butylmethyltin compounds can be determined. Such factors varied only - 1.8% over a concentration range of 3 to 70%. 

The following chemicals were used without further ourifi-cation dibutyltin dichloride (Fisher Scientific Co., Fairlawn, N.J.), diphenyltin dichloride (Metallomer Laboratories, Maynard, Mass.), dibutyltin dibromide, dilauryltin dichloride, tri-n-propyltin chloride, diethyltin dichloride, dimethyltln dichloride, dioctyltin dichloride, tricyclohexyltin bromide, triphenyltin dichloride and tribenzyltin chloride (all from Ventron-Alfa Inorganics, Danvers, Mass.), tri-n-butyltin chloride (Aldrich Chemical Co., Milwaukee, Wis.) and dextran (molecular weight - 200,000 - 300,000 United States Biochemical Corp., Cleveland, Ohio). 

Two nonclassical interfacial systems have been developed by Carraher and co-workers (3,10). One utilizes a typical aqueous phase containing a Lewis base (here the dextran) and an added base brought together with a liquid Lewis acid, here a liquid stannane. Thus liquid stannanes such as tributyltin chloride and dibutyltin dibromide can be condensed with aqueous solutions containing the cellulose. Modification was successfully carried out for the majority of liquid stannanes (Table 2). 

Inflammatory changes consisting of hyperemia and bronchitis were observed in the respiratory system of rabbits exposed to 4-6 mg/m (0.30-0.45 ppm) tributyltin chloride for 95 days (Gohlke et al. 1969). Histopathology, consisting of severe bronchitis and vascular and alveolar edema, was seen in rats exposed to 2 mg tin/m (0.41 ppm) as a mixture of tributyltin dibromide (0.39 ppm), dibutyltin bromide (0.02 ppm) and hydrocarbon impurities for 80 days (Iwamoto 1960). Since these were terminal histopathological evaluations only, it is not known whether the changes were reversible or would have produced functional impairment in the animals if exposure had continued. 

---