Thionyl bromide

Hydrogen sulfide is a poisonous gas of density 0.96, melting point — 82.9°C., boiling point — 59.4°C., critical temperature 100.5°C., critical pressure 89 atm., surface tension 25.43 dynes, specific conductance 0.2 X 10-9, dielectric constant 8.6, and viscosity 0.0041 dyne per centimeter. 

Submitted by Harold Hibbert and J. C. Pullman Checked by H. S. Booth) and Clarence Seabright) 

The following procedure consists of passing anhydrous hydrogen bromide through cold technical thionyl chloride. 

The hydrogen bromide was passed into 50 ml. of technical thionyl chloride for 12 hours at 0°C., yielding a reddish liquid which on distillation under diminished pressure in an all-glass apparatus gave 50 ml. of an orange-red liquid, boiling constantly at 69 to 70°C. at 62 mm. On redistillation, the product boiled at 48°C. at 20 mm. and was orange-yellow in color. 

Analysis gave 76.68 and 76.85 per cent bromine, the theory being 76.88 per cent bromine. The yield is almost quantitative. The specific gravity by the Westphal balance method is 2.688 at 20°C. It freezes at — 52°C. Thionyl bromide decomposes slowly on standing and should be kept in bottles with tight-fitting glass stoppers. 

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Chemical Properties. Thionyl chloride chemistry has been reviewed (169—173). Significant inorganic reactions of thionyl chloride include its reactions with sulfur trioxide to form pyrosulfuryl chloride and with hydrogen bromide to form thionyl bromide [507-16-4]. With many metal oxides it forms the corresponding metal chloride plus sulfur dioxide and therefore affords a convenient means for preparing anhydrous metal chlorides. 

Thionyl bromide [507-16A], SOBr2, is used to convert alcohols to bromides (52). 

One scheme for preparation of the diamine side chain consists in first reducing the carbonyl group of the haloketone, 73. Displacement of the halogen with diethylamine gives the amino alcohol (74). Treatment of that intermediate with thionyl bromide serves to replace the hydroxyl by bromine (75). The synthesis is completed by displacement of the bromine with ammonia. 

Radical phthalocyanine species, e.g. 6, can be prepared by the reaction of thionyl chloride or thionyl bromide with metal phthalocyanines. In these cases, the phthalocyanine ligand only carries the charge — l.349... 

C4H5O4S 70-49-5) see Erythromycin monopropionate mercaptosuccinate Sodium aurothiomalate thionyl bromide... 

Smirnov-Zamkov et al. have shown that sulfur dioxide and hydrogen bromide react with alkynes with phenylacetylene derivatives, such as the sulfonamide (42), a benzo[b]thiophene (43) is formed.50 The mixture of sulfur dioxide and hydrogen bromide appears to behave like thionyl bromide, cf. thionyl chloride (see Section V,B). 

Thionyl bromide, 23 647 Thionyl chloride, 23 642, 647-651 end use of chlorine, 6 135t commercial production of, 23 650 economic aspects of, 23 650 health and safety factors related to, 23 650... 

In 1963, an asymmetric synthesis of chloroallenes was reported by the SNi reaction of propargyl alcohols with thionyl chloride [34]. Since then, rearrangement of pro-pargylic precursors has been one of the most useful methodologies for the synthesis of allenes [35]. Treatment of 84, obtained by asymmetric reduction with LiAlH4-Dar-von alcohol complex, with thionyl bromide gave 86 as the major product via 85 (Scheme 4.21) [36],... 

Scheme 4.21 Asymmetric synthesis of bromoallenes with thionyl bromide.

SOBr2 THIONYL BROMIDE 1.5135 -1.9716E+03 2.6530E+00 -2.2814E-03... 

Selective chlorination or bromination of the 5 -hydroxyl group in unprotected D-ribonucleosides has been achieved75 by treatment with thionyl chloride or thionyl bromide, respectively, in hexamethyl-phosphoric triamide at room temperature for 10-15 hours the 5 -deoxy-5 -halogeno derivatives of cytidine and adenosine have been prepared in this way. The reactions presumably occur by way of alkoxyphosphonium salts as intermediates.78... 

Even at the ordinary temperature hydrogen iodide is readily decomposed by thionyl chloride, giving hydrogen chloride, iodine, sulphur and sulphur dioxide, but hydrogen bromide undergoes a double decomposition with formation of thionyl bromide and hydrogen chloride 3... 

Thionyl Bromide, SOBr2.—This analogue of thionyl chloride is best prepared by the prolonged action of hydrogen bromide on thionyl chloride 3... 

Besson,5 when preparing thionyl bromide by the action of boiling thionyl chloride on hydrogen bromide or aluminium bromide, claimed to have isolated the intermediate compound, thionyl chlorobromide, SOCIBr, a more volatile liquid than thionyl bromide and therefore separated from it by distillation under reduced pressure. The product isolated was a yellow liquid, density 2-31 at 0° C., boiling with slight... 

Halides and Oxyhalides op Sulphur —Fluorides, Chlorides, Sulphur Bromide, Sulphur and lodino, Oxyfluorides, Oxychlorides, Thionyl Bromide. 

The application of the solvent system concept to liquid sulfur dioxide chemistry stimulated the elucidation of reactions such as those of aluminum sulfite. However, there is no direct evidence at all for the formation of S02+ in solutions of thionyl halides. In fact, there is evidence to the contrary. When solutions of thionyl bromide or thionyl chloride are prepared in 3JS-labeled (S ) sulfur dioxide, almost no exchange takes place. The half-life for the exchange is about two years or more. If ionization took place ... 

The feci that labeled thionyl bromide exchanges with thionyl chloride indicates that perhaps the ionization shown in Eq. 9.3S actually occurs as10... 

The addition of hydrogen bromide and sulfur dioxide to phenylpropiolic acid (210) in diethyl ether at -50 °C is reported to give 3-bromobenzo[6]thiophene-2-carboxylic acid (211) (75ZOR1776). If hydrogen bromide and sulfur dioxide can react under these conditions to give thionyl bromide, the reaction is similar to the reaction of thionyl chloride with unsaturated acids, reported in the previous section. 

Thionyl bromide is very sensitive to moisture heat and direct light. It reacts with water to produce sulfur dioxide and hydrobromic add under illumination the liquid turns dark red, with the formation of SO 6r and S2Br2 as decomposition products. Inert organic solvents readily dissolve the material. 

A method for making thionyl bromide using KBr and thionyl chloride in liquid sulfur dioxide in 50% yield is described in reference 5. 

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