Phosphorus pentabromide

However, phosphorus pentachloride in the solid state has an ionic lattice built up of (PC ) and (PClg)" ions and these ions are believed to exist in certain solvents. Thus under these conditions the maximum covalency is reached with chlorine. In phosphorus pentabromide, PBrj, the solid has the structure [PBr4] [Br] . 

Trimethylene dibromide (Section 111,35) is easily prepared from commercial trimethj lene glycol, whilst hexamethylene dibromide (1 O dibromohexane) is obtained by the red P - Br reaction upon the glycol 1 6-hexanediol is prepared by the reduction of diethyl adipate (sodium and alcohol lithium aluminium hydride or copper-chromium oxide and hydrogen under pressure). Penta-methylene dibromide (1 5-dibromopentane) is readily produced by the red P-Brj method from the commercially available 1 5 pentanediol or tetra-hydropyran (Section 111,37). Pentamethylene dibromide is also formed by the action of phosphorus pentabromide upon benzoyl piperidine (I) (from benzoyl chloride and piperidine) ... 

Phosphorus pentabromide [7789-69-7] M 430.6, m <100 , b 106 (dec). Dissolved in pure nitrobenzene at 60°, filtering off any insoluble residue on to sintered glass, then crystallised by cooling. Washed with dry Et20 and removed the ether in a current of dry N2. (All manipulations should be performed in a dry-box.) [Harris and Payne J Chem Soc 3732 1958]. Fumes in moist air because of hydrolysis. HARMFUL VAPOURS. 

Replacement of a hydrogen with bromine in the polyfluoroalkyl group of a ketone or acyl fluoride can be carried out with phosphorus pentabromide [i50] (equation 45)... 

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. 

A classical procedure for the synthesis of the A-(1-chloroalkyl)amides1 or carbamates68 involves substitution of the hydroxy group in stable A-( 1-hydroxyalkyl)amides (or carbamates) by a halogen function with reagents such as thionyl chloride, phosphorus pentachloride, phosphorus pentabromide, etc. In certain cases merely heating in concentrated hydrochloric or hydrobromic acid suffices1. 

An interesting feature of phosphorus pentachloride is that it is an ionic solid of tetrahedral PC14+ cations and octahedral PC16 anions, but it vaporizes to a gas of trigonal bipyramidal PC15 molecules (see Section 2.10). Phosphorus pentabromide is also molecular in the vapor and ionic as the solid but, in the solid, the anions are simply Br ions, presumably because six bulky Br atoms simply do not fit around a central P atom. 

Using Phosphorus Tribromide, Phosphorus Pentabromide, or Phosphoryl Bromide... 

The methods of preparing pentamethylene bromide are given in Org. Syn. Coll. Vol. 1, 1941, 428, where the preparation of the dihalide from benzoylpiperidine and phosphorus pentabromide is described in detail. The procedure given above is based upon the work of Paul.1... 

Stability calculations on the phosphoranes (79) have appeared.71 Various potential functions for phosphorus pentafluoride (73 n = 0) have been reported.72 73 An e.s.r. study of y-irradiated phosphorus pentachloride has been published.74 New thermochemical data on phosphorus pentabromide have appeared.76... 

Bromine reacts with phosphorus to form pbospborus tribromide, PBrs or phosphorus pentabromide, PBrs. The pentabromide forms in tbe presence of excess bromine. Bromine oxidizes hydrogen sulfide to sulfur ... 

Reaction with phosphorus pentabromide yields phosphorus oxybromide ... 

General Reaction Chemistry of Sulfonic Acids. Sulfonic acids may be used to produce sulfonic acid esters, which are derived from epoxides, olefins, alkynes, allenes, and ketenes, as shown in Figure 1 (10). Sulfonic acids may be converted to sulfonamides via reaction with an amine in the presence of phosphorus oxychloride [10025-87-3], POCl3 (11). Because sulfonic acids are generally not converted direcdy to sulfonamides, the reaction most likely involves a sulfonyl chloride intermediate. Phosphorus pentachloride [10026-13-8] and phosphorus pentabromide [7789-69-7] can be used to convert sulfonic acids to the corresponding sulfonyl halides (12,13). The conversion may also be accomplished by continuous electrolysis of thiols or disulfides in the presence of aqueous HQ [7647-01-0] (14) or by direct sulfonation with chlorosulfuric acid. Sulfonyl fluorides are typically prepared by direct sulfonation with fluorosulfuric acid [7789-21-1], or by reaction of the sulfonic acid or sulfonate with fluorosulfuric acid. Halogenation of sulfonic acids, which avoids production of a sulfonyl halide, can be achieved under oxidative halogenation conditions (15). 

Phenyl iso-thiocyanate, 642,643 Phenylthioureas, 422, 655 Phenylurea, 644, 645 Phenylurethanos, 264 Phloroacetophenone, 727, 736 Phosgene, 185 Phosphoric acid, 189, 284 Phosphorus, detection of, 1043 Phosphorus, red, purification of, 193 Phosphorus oxychloride, 367 Phosphorus pentabromide, 489, 492 Phosphorus pentachloride, 799, 822, 974 Phosphorus pentoxide, handling of, 407 Phosphorus tribromide, 189, 492 Phosphorus trichloride, 367 Phosphorus trisulphide," 836 Phthalamide, 983 Phthalein test, 681 ... 

Tiffeoeau and Fourne u 01 obtained 1,2-dibromo-l-phenyl ethane on treatment of styrene oxide with phosphorus pentabromide. Thi., transformation could bo imagined to proceed by way of oxotiiwu complex formation, followed by Br ion attack as shown in Eq. (U50 ... 

General Reaction Chemistry of Sulfonic Acids. Sulfonic acids may he used to produce sulfonic acid esters, which are derived from epoxides, olefins, alkynes, allenes, and kelenes, as shown in Figure 1. Phosphorus pentachloride and phosphorus pentabromide can be used to convert sulfonic acids to the corresponding sulfonyl halides. 

Two products (128 and 129) were obtained when 1,6-naphthyridin-4-one (127) reacted with phosphorus pentabromide.143 It is presumed that 128 is the precursor of 129. The 4-bromo derivative was obtained when compound 127 was treated with phosphorus oxybromide. The 3-bromo-l,6-naphthyridin-4-one (130) was prepared in good yield from compound 127, and on reaction with phosphorus oxybromide the 3,4-dibromo-l,6-naphthyridine (131) could be obtained. The reaction of l,7-naphthyridin-8-one with phosphorus oxybromide is unique,144 since it appears to be the only example in this series, in which further bromination occurs with this reagent, affording 8-monobromo and 3,8-dibromo-l,7-naphthyridine. 

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