Phosphorous tribromide with alcohols

Phosphorus tribromide reacts with alcohols to give alkyl bromides and phosphorous acid. 

Phosphine(s), chirality of, 314 Phosphite, DNA synthesis and, 1115 oxidation of, 1116 Phospholipid, 1066-1067 classification of, 1066 Phosphopantetheine, coenzyme A from. 817 structure of, 1127 Phosphoramidite, DNA synthesis and, 1115 Phosphoranc, 720 Phosphoric acid, pKa of, 51 Phosphoric acid anhydride, 1127 Phosphorus, hybridization of, 20 Phosphorus oxychloride, alcohol dehydration with. 620-622 Phosphorus tribromide, reaction with alcohols. 344. 618 Photochemical reaction, 1181 Photolithography, 505-506 resists for, 505-506 Photon, 419 energy- of. 420 Photosynthesis, 973-974 Phthalic acid, structure of, 753 Phthalimide, Gabriel amine synthesis and, 929... 

Alcohols can be converted to alkyl halides by reaction with thionyl chloride, SOCI phosphorous trichloride, PCI phosphorous pen-tachloride, PCI or phosphorous tribromide, PBr3. For example, ethyl chloride or ethyl bromide can be prepared from ethyl alcohol via reactions with sulfur and phosphorous halides. 

Because thionyl bromide is relatively unstable, alkyl bromides are normally prepared by reacting the alcohol with phosphorous tribromide (PBr3). 

This reaction proceeds via a two-step mechanism. In the first step, the alcohol reacts with the phosphorous tribromide. 

The steric course of additions of amines and alcohols to acetylene dicarboxylic ester was studied under various conditions. Secondary amines gave stereospecifically cis addition product. Nitrosyl formate can be generated in situ in the presence of an olefin to yield the nitrosoformate which on hydrolysis affords the hydroxynitroso compound in high yield. Transoximination gave the a-hydroxy ketone. Phosphorous tribromide can be added to olefins to yield 1 1 adducts with uv irradiation, peroxides, or heat as initiators ... 

The reported synthesis for (5Z,9Z)-14-methylpentadeca-5,9-dienoic acid (14) started with commercially available 4-methylpentan-l-ol, which upon reaction with phosphorous tribromide afforded l-bromo-4-methylpentane [52], Commercially available pent-4-yn-l-ol was also protected as the tetrahydropyranyl ether as shown in Fig. (18). Formation of the lithium acetylide with n-BuLi in THF and subsequent addition of 1-bromo-4-methylpentane in hexamethylphosphoric acid triamide resulted in the isolation of the tetrahydropyranyl protected 9-methyldec-4-yn-l-ol. Hydrogenation of the alkyne with Lindlar s catalyst and quinoline in dry hexane afforded the cis hydropyranyl-protected 9-methyldec-4-en-l-ol. Deprotection of the alcohol with />-toluenesulfonic acid afforded (Z)-9-methyldec-4-en-l-ol. Pyridinium chlorochromate oxidation of the alcohol resulted in the isolation of the labile (Z)-9-methyldec-4-enal. Final Wittig reaction with (4-carboxybutyl) triphenylphosphonium bromide in THF/DMSO resulted in the desired (5Z,9Z)-14-methylpentadeca-5,9-dienoic acid (14). 

Phosphorous acid, esters, 596 Phosphorus pentoxide, 814 Phosphorus tribromide, reachon with alcohols, 147, 161... 

If phosphorous tribromide is used instead, then the bromine anion will be formed by ionization of Br from PBr3. The Br will then react with isopentyl alcohol to produce isopentyl bromide. 

The reaction of 1,2-oxazine 23 with phosphorous tribromide afforded the 5-bromomethyl-2-(phenylimino)tetrahydrotoan 26 via an initial transformation of the alcohol into a bromide functionality 24 and subsequent Beckmann rearrangement via 25. ... 

Many hydroxypyrazine A oxides have been A(-deoxygenated to pyrazines with a variety of reducing agents which include heating with hydrazine hydrate in alcohols hydriodic acid and red phosphorus in acetic or phosphoric acid iodine and red phosphorus in refluxing acetic acid phosphorus tribromide in ethyl acetate sodium dithionite catalytic reduction with hydrogen over Raney nickel dry distillation with copper-chromite catalyst and titanium trichloride in tetrahydrofuran at room temperature. 

Many simple compounds of phosphorus are known, but they do not warrant detailed description here. Esters of phosphoric acid and phosphorous acid are formed when the halides of phosphorus are treated with an alcohol. It has already been pointed out that the interaction of these substances yields alkyl halides, a number of reactions taking place simultaneously. Typical reactions are those which take place between alcohol and phosphorus tribromide —... 

The reaction of an alcohol with phosphorus tribromide produces phosphorous acid, which has a high boiling point, and is water soluble. Therefore, the bromoaUtane can be separated from the reaction mixture by distillation or by adding water to dissolve the phosphorous acid and then extracting the hahde with ether. 

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