Phosphorus tribromide, hydrolysis

The hydrolysis of phosphorus tribromide or triiodide is used in the preparation of hydrogen bromide and hydrogen iodide respectively ... 

A similar reaction sequence of triisopropylphenylphosphole or mesitylphosphole (17b and 17a, respectively) with phosphorus tribromide afforded the corresponding 2-substituted products. The reaction of dibromophosphine 37 with nucleophiles followed by oxidation or hydrolysis gave phosphonic or //-phosphinic derivatives (39 or 41, respectively) (Scheme 9) [48, 49], The regioselectivity is obviously the consequence of the presence or the lack of the steric hindrance with ortho tert-butyl groups, only position 3 is available, while with the smaller triisopropyl substituent, position 2 may be the appropriate reaction site. 

The preparation can be carried out with phosphoric acid in place of sulfuric acid, but it is customary instead to prepare hydrogen bromide in the laboratory by the hydrolysis of phosphorus tribromide, PBrg. The reaction can be carried out by mixing red... 

Write the equations for the hydrolysis of phosphorus tribromide and for the hydrolysis of phosphorus pentachloride. 

Bromomorphide, believed to be analogous to [vi], is formed by the action of phosphorus tribromide on morphine [82], A mixture of a-, /3-, and y-isomorphines, but no morphine, is obtained by the hydrolysis of the lialogenomorphides [454-53,463-4,82], The conversion of morphine through the chloride to isomers of morphine resembles the geraniol-liimlool conversion [465, 466]. The halogenomorphides are discussed 111 detail in Chapter VIII. 

This compound must arise from bromonium ion cyclization of the 6,7-bromohydrin of farnesol acetate. Hydrolysis of the acetate group in (47) and sequential treatment with phosphorus tribromide and water gave obtusenol (46). Other syntheses of marine sesquiterpenoids include those of pallescensin-E (48),30 furoventalene (49),81 and dactyloxene-B (50) and -C (51).32 The last mentioned established the absolute configurations of the two dactyloxenes. A second synthesis of ancistrofuran (53) and its C-2 epimer has been recorded starting from the lactone (52) which is derived from homogeranic acid (Scheme 3).33... 

Hydroxyalkylthiazoles are also obtained by cyclization or from alkoxyalkyl-thiazoles by hydrolysis (36, 44, 45, 52, 55-57) and by lithium aluminium hydride reduction of the esters of thiazolecarboxylic acids (58-60) or of the thiazoleacetic adds. The Cannizzaro reaction of 4-thiazolealdehyde gives 4-(hydroxymethyl)-thiazole (53). The main reactions of hydroxyalkyl thiazoles are the synthesis of halogenated derivatives by the action of hydrobroraic acid (55, 61-63), thionyl chloride (44, 45, 63-66), phosphoryl chloride (52, 62, 67), phosphorus penta-chloride (58), tribromide (38, 68), esterification (58, 68-71), and elimination that leads to the alkenylthiazoles (49, 72). 

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