Phosphorus III Bromide

The various published methods for the preparation of phosphorus (III) bromide are all variations of the simple but 

II Present address College of Pharmacy, University of Illinois, Chicago, lU. 

One hundred twenty-five grams of dry red phosphorus (dried in an oven for 3 hours at 105° and preserved for 

Caution. No less than the amount of phosphorus(III) bromide or phosphorus(III) chloi-ide indicated for 125 g. of phosphorus should he used. If there is not enough liquid to make a mobile suspension of phosphorus, the phosphorus may hold back the vapors of the suspending medium long enough for them to build up sufficient vapor pressure to cause an explosion. 

An amount of bromine equivalent to 100 g. of phosphorus, 773.5 g., is weighed out and about half of it placed in the separatory funnel. An air bath is placed around the flask and the reaction mixture brought to boiling. The bromine is allowed to drop in slowly for a period of about 5 minutes until the inlet tube is filled with bromine vapor. The flame is now removed and the bromine added rapidly enough (about 20 ml./minute) to cause the reaction mixture to boil from the heat of reaction. After all the bromine has been added, the flame is replaced and boiling continued for 10 minutes. 

Form Supplied in widely available as liquid and 1.0 M solution in CH2CI2. 

Purification generally used without purification can be distilled under N2 at atmospheric pressure. 

Handling, Storage, and Precautions corrosive. The colorless, fuming liquid has a very penetrating odor. It has a vapor pressure of 10 mmHg at 48 °C. The reagent is stable if kept dry, but reacts violently with water. It is extremely destructive to tissue of mucous membranes, upper respiratory tract, eyes, and skin. This reagent should only be used in a fume hood. 

Conversion of Alcohols to Bromides. The conversion of alcohols (ROH) into bromides (RBr) using PBr3 is very general. Reaction conditions for this transformation are quite varied. Each 

The reagent will convert an alcohol to a bromide in the presence of an ether (eq 10). Acetals are also stable to the bromination procedure, although an interesting reaction of a cyclopropanone acetal has been reported (eq 11).  

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Phosphor-athcr, m. phosphoric ether (ester of phosphoric acid, specif, ethyl phosphate), -basis, phosphorus base, -bestimmung, /. determination of phosphorus, -blei, n. lead phosphide Min.) pyromorphite. -bombe, f. phosphorus bomb. -brandgranate, /. phosphorus incendiary shell, -brei, m. phosphorus paste, -bromid, n. phosphorus bromide, specif, phosphorus pentabromide, phos-phorus(V) bromide, -bromijr, n. phosphorus tribromide, phosphorus(III) bromide, -bronze, /. phosphor bronze, -calcium, n. calcium phosphide, -chlorid, n. phosphorus chloride, specif, phosphorus pcntachloride, phosphorus(V) chloride, -chloriir, n. phosphorous chloride (phosphorus trichloride, phosphorus(III) chloride), -dampf, tn. phosphorus vapor or fume, -eisen, n. ferrophos-phorus iron phosphide, -eisensinter, m. diadochite. 

Phosphine, trianilino-, formation of, from trimethyl(anilino)silane and phosphorus(III) bromide, 5 61... 

Phosphorus, mixture of, with diphosphorus tetraiodide, 2 143 Phosphorus (III) bromide, 2 147 Phosphorus(III) chloride, 2 145 Phosphorus (V) chloride, 1 99 Phosphorus (III) S-chloroethoxydi-chloride, 4 66... 

Phenyldibromophosphine has been prepared by an exchange reaction between phosphorus(III) bromide and diphenylmercury, but only in low yields. A more convenient procedure, and one giving excellent yields, involves... 

Bromocyclopropanes have also been prepared in reactions involving formation of a C-Br bond at the expense of a C-O bond. When 1-ethoxy-l-trimethylsiloxycyclopropane reacted with phosphorus(III) bromide, 1-bromo-l-ethoxycyclopropane (17) was obtained in 65-75% yield. Cleavage of C-O bonds occurred when trifluoromethanesulfonyloxycyclopropane was exposed to a cyclopentane solution of tributylcetylphosphonium bromide at 70 °C bromocyclopropane (18) was obtained in 95% yield along with 3-bromopropene (5%). ... 

A new synthesis of nornictyrine (61) requires as the final steps reactions of the W-oxide (60) with phosphorus (III) bromide and then with sodium hydroxide (S. Saeki, T. Takaaki and M. Hamana, Heterocycles, 1984, 22, 545). 

Oxy-diazines, with the oxygen a to nitrogen, can be converted into halo- and thio compounds " using the same reagents used for 2- and 4-pyridones, including M-bromosuccinimide with triphenylphosphine. " The reactions of 0-silylated pyrazinones with phosphorus(III) bromide or phosphorus(V) chloride are also efficient. ... 

An interesting example of the formation and reaction of a /7-silylcarbonium ion was reported independently by Eaborn61 and Jarvie62. Reaction of the dideuterio-/Miydroxy-silane 3 with phosphorus(III) bromide gave the directly substituted bromide, 6, together with the rearranged bromide, 5. 

C303 Carbon suboxide 0 1.453 PBt3 Phosphorus(III) bromide 25 1.687... 

The phosphorus (V) chloride-boron chloride complex has been prepared by the chlorination of the phosphorus(III) bromide-boron bromide complex at room temperature, by chlorinating an equimolar mixture of phosphorus (III)... 

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