Tin bromides

Another similar example is shown by the reaction between ris(pentafluo-rophenyI)tin bromide and ethylmagnesium bromide (equation 8)... 

Brom-wasserstoffsaure, /. hydrobromic acid, -wismut, tn. n. bismuth bromide, -zahl, /. bromine number, -zink, n. zinc bromide, -zinn, n. tin bromide. 

Tin, nitratodiphenyltris(dimethy) sulfoxide)-structure, 1,77 Tin, nitratotris(triphenyltin)-structure, 1, 47 Tin,tetrakis(acetato)-stereochemistry, 1,94 Tin, tetrakis(diethyldithiocarbamato)-angular parameters, 1, 57 Tin, tetrakis(ethyldithiocarbamato)-angular parameters, 1, 57 Tin, tetranitrato-stereochemistry, 1, 94 Tin, tri-n-butylmethoxy-, 3, 208 Tin alkoxides physical properties, 2, 346 Tin bromide, 3, 194 Tin bromide hydrate, 3,195 Tin carboxylates, 3, 222 mixed valence, 3, 222 Tin chloride, 3, 194 hydroformylation platinum complexes, 6, 263 Tin chloride dihydrate, 3,195 Tin complexes, 3, 183-223 acetyl ace tone... 

Reactions on a smaller scale tended to give better yields for the reduction of the fluorous tin bromide to fluorous tin hydride. 

Tris[(2-perfluorohexyl)ethyl]tin hydride has three perfluorinated segments with ethylene spacers and it partitions primarily (> 98%) into the fluorous phase in a liquid-liquid extraction. This feature not only facilitates the purification of the product from the tin residue but also recovers toxic tin residue for further reuse. Stoichiometric reductive radical reactions with the fluorous tin hydride 3 have been previously reported and a catalytic procedure is also well established. The reduction of adamantyl bromide in BTF (benzotrifluoride) " using 1.2 equiv of the fluorous tin hydride and a catalytic amount of azobisisobutyronitrile (AIBN) was complete in 3 hr (Scheme 1). After the simple liquid-liquid extraction, adamantane was obtained in 90% yield in the organic layer and the fluorous tin bromide was separated from the fluorous phase. The recovered fluorous tin bromide was reduced and reused to give the same results. Phenylselenides, tertiary nitro compounds, and xanthates were also successfully reduced by the fluorous fin hydride. Standard radical additions and cyclizations can also be conducted as shown by the examples in Scheme 1. Hydrostannation reactions are also possible, and these are useful in the techniques of fluorous phase switching. Carbonylations are also possible. Rate constants for the reaction of the fluorous tin hydride with primary radicals and acyl radicals have been measured it is marginally more reactive than tributlytin hydrides. ... 

D. Tris[(2-peiiluorohexyl)ethyl]tin hydride (Note 7). A 1-L, three-necked flask and a stirring bar are dried in an oven. The fluorous tin bromide (13.8 g, 11.1 mmol) is dissolved in dry ether (275 mL) and transferred to the dried three-necked flask equipped with a thermometer, stirring bar, and an outlet to argon. The solution is cooled to O C. AIM solution of iithium aluminum hydride (LAH) in ether (11.1 mL, 11.1 mmol) is added dropwise over 45 min to the solution. The addition rate is adjusted to maintain a temperature between 0° and 1°C. The reaction mixture is stirred for 6 hr at 0°C. Water (75 mL) is slowly added (initially dropwise) with stirring to the ice-cold mixture. Sodium potassium tartrate (20%) (250 mL) is added and the mixture is transferred to a 1-L separatory funnel. The ethereal layer is separated and the aqueous layer is extracted three times with ether (3 x 100 mL). The combined extracts are dried with magnesium sulfate and vacuum filtered into a 1-L, round-bottomed flask. The solvent is evaporated under reduced pressure. The cmde product is distilled under a reduced pressure of 0.02 mm at 133-140°C to provide 11.3 g (9.69 mmol, 87%) of the pure product as an oil (Notes 8 and 9). 

Tin dissolves easily in concentrated acids, however, and in hot alkaline solutions, such as hot, concentrated potassium hydroxide (KOH). The metal also reacts with the halogens to form compounds such as tin chloride and tin bromide. It also forms compounds with sulfur, selenium, and tellurium. 

A fluorous surfactant covalently tethered to silica provides a thin film of perfluorinated solvent for reactions and/or extractions. This material was used for the small-scale hydrocyclization of 6-bromo-1-hexene with NaBH and a catalytic amount of a fluorous tin bromide in 1-butanol. The yield of methylcyclopentane was modest, however, and this technology is a long way from being viable on an industrial scale. The same idea has been more successfully employed with fluorous silica-supported tin Lewis acid catalysts for Baeyer-Villiger oxidations. ... 

This procedure illustrates the bromopropylation of an alcohol by allylation and then hydroboration/bromination,7 a clean, selective procedure compared with other approaches via 3-substituted propyl bromide derivatives. Conversion to the tetraalkyl tin, then brominative cleavage, is the standard sequence for preparation of trialkyl tin derivatives.8 The standard lithium aluminum hydride (UAIH4) reduction of the tin bromide was not usable here because of contamination of the product by UAIH4 byproducts that were not easily separated, and the polymethylhydrosiloxane reduction method9 was not successful. However, use of NaBH4 in f, 2-dimethoxyethane was effective and convenient.10... 

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