Phosphor pentabromide

Pyridones or hydroxypyridines can readily be converted to the corresponding halide by a number of different reaction conditions [24], The use of phosphorous trichloride for transformation was demonstrated in the conversion of 72 to chloride 73. The exchange of chlorine for iodine, as in 74, has already been discussed (vide supra). The corresponding bromide could be obtained using phosphorous tribromide or phosphorous pentabromide, as in the conversions of 72 to 75 and 76 to 77. 

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. 

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 ... 

Discussion When a bromide is treated with concentrated sulphuric acid, hydrobromic acid and an acid sulphate are formed, as would be expected but then a further reaction takes place. Just as hydrochloric acid can be oxidized by a sufficiently strong oxidizing agent, as was shown in Experiment 23, so hydrobromic acid also may be oxidized. But this latter compound is more readily oxidized than hydrochloric acid and even sulphuric acid, which does not react with hydrochloric acid, serves to bring about this oxidation. Hence the hydrobromic acid expected from the double decomposition of a bromide and sulphuric acid will contain bromine and the reduction products of the sulphuric acid. Pure hydrobromic acid may be prepared by the substitution of phosphoric for sulphuric acid or by some entirely different method, such as the reaction between phosphorus pentabromide and water. 

This body is fomted by the aotion of a small quantify of water upon the pentabiomide, but it m best pepared by dukU ing pentabromide of jdmsphorus with oxalic acid (Baudrimont). This substance forms a mass of flat tabular ccys wUrithaTe a spedfic gravify of 2 822 (Bittei), melt at 48 and boil at 195. Water decomposes the oxybtomxle into phosphoric and bydro-bromic adds. 

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