Phosphorus V Bromide

Related Reagents. A number of related reagents have been used for the conversion of alcohols to bromides. Other reagents for this purpose covered in this encyclopedia include l,2-Bis(diphenylphosphino)ethane Tetrabro-mide, Bromine-Triphenyl Phosphite, Hydrogen Bromide, Triphenylphosphine-Carbon Tetrabromide, and Triphenylphos-phine Dibromide.  

Physical Data mp 179-181 °C The Merck Index (11th ed.) reports dec above 100 °C. 

Form Supplied in yellow solid commercially available. 

Preparative Method from Bromine and Phosphorus(III) Bromide with which it is in equilibrium. 

Handling, Storage, and Precautions corrosive and highly toxic stable if kept dry, but reacts violently with water store under N2 at rt use in a fume hood. 

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Pentabromphosphor, n. phosphorus penta-bromide, phosphorus(V) bromide, pentacarbocyclisch, a. pentaearbocyelie. Pentathionsaure, /. pentathionie aeid. pentazyklisch, a. pentaeyelie. 

Fifty grams of phosphorus (V) bromide are first prepared, either by allowing 18,5g of bromine to drop slowly into 31.5g of ice-cold phosphorus tribromide, or by dropping 46.5g of bromine dropwise on 3.6g of dry red phosphorus. Either reaction is conducted in a stout pressure bottle of about 500ml capacity moisture must be carefully excluded. 

The bottle and contents are now cooled to — 20°C in a bath of dry-ice and acetone and about 100ml of previously condensed sulfur dioxide [hood ] are rapidly introduced into the vessel. The bottle is sealed and placed behind a safety screen for about 8 days at 35CC. During this time the yellow crystals of phosphorus (V) bromide slowly dissolve completely in the excess sulfur dioxide to yield a red solution. When all the pentabromide has disappeared the bottle is recooled to 20°C and cautiously opened. A drying tube... 

Solid phosphorus(v) bromide is also ionic, [PBr4]+Br-. There is even an AsClJ ion, which occurs with such large anions as PClg, A1C14, and AuCl4 even though AsC15 does not exist. 

The phosphonitrile bromides were first obtained by the ammonolysis of phosphorus(V) bromide. Reported prepa- University of Illinois, Urbana, 111. 

PNBr2-PBr Phosphonitrile bromide compound, with phosphorus (V) bromide, 7 77 (PNBr2)3 Phosphonitrile bromide, trimeric, 7 76... 

Phosphorus (V) bromide is first prepared by slowly adding 370 g. of liquid bromine to 630 g. of phosphorus (III) bromide (or by reaction between red phosphorus and bromine as described in synthesis 45) in a 1-liter pyrex distilling flask. The bromine is added through a separatory funnel inserted through one hole of a two-hole rubber stopper in the neck of the flask. To allow for expansion of gases and to prevent hydrolysis, a horizontal drying tube containing phosphorus(V) oxide is connected to a tubular... 

The two solids are thoroughly mixed, the stopper is then replaced, and the flask is gently heated on a water bath for several hours until the mass has completely liquefied. Strong heating must be avoided up to this point to prevent decomposition of the phosphorus(V) bromide. The distilling flask is then connected to an air condenser, and the liquid is heated more and more strongly for about an hour and finally distilled over at atmospheric pressure, the first and last portions being discarded. Yield about 80 per cent [based on the phosphorus (III) bromide]. 

Of the various methods of preparing phosphorus (V) sulfobromide, experience has shown that the simplest is that of Michaelis. In consists of digesting phosphorus(V) sulfide and phosphorus (V) bromide until the reaction is complete, followed by suitable purification. 

Thirty-one grams of dry red phosphorus is placed in the flask, and 400 g. of liquid bromine is slowly added through the separatory funnel while the flask is cooled by running tap water over it. Next, 100 g. of phosphorus(V) sulfide is added to the phosphorus(V) bromide, just prepared, and the mass is heated on a water bath (or steam cone) for 2 hours. The flask is then heated more vigorously with a direct flame until its contents are completely liquid. 

Iodine bromide and arsenic(III) bromide resemble closely as solvents iodine monochloride and arsenic(III) chloride respectively, and stable acids have not been isolated in the bromo-systems. Molten mercury(II) bromide is an excellent solvent for various classes of compounds. Alkali metal bromides form solvated anionic species which appear to contain the ions [IBr2] , [AsBr4] and [HgBr3] respectively and phosphorus(V) bromide gives PBr4+IBr2 in iodine bromide where it behaves as a base. Other basic substances are nitrogenous bases such as pyridine. 

Q5 Phosphorus(iii) bromide is a colourless liquid. Phosphorus(v) bromide is a yellow solid which sublimes when heated. 

The solid is ionic and consists of [PBr4]+ and Br ions, but in the gas phase PBrg molecules are present. Phosphorus(v) bromide is hydrolysed by water producing hydrogen bromide gas ... 

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