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外観
無色〜黄褐色, 澄明〜微濁の液体
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溶解性
水, アルコールと反応。アセトン, ベンゼン, 二硫化炭素に易溶。二硫化炭素、エタノール、ジエチルエーテル、アセトン、クロロホルム及びベンゼンに溶けやすい。
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化学的特性
Phosphorus tribromide is a colourless liquid(possibly hazy) with the formula PBr3. It fumes in air due to hydrolysis and has a penetrating odour. It is widely used in the laboratory for the conversion of alcohols toalkyl bromides.
Phosphorus tribromide (PBr3) is commonly used in Hell-Volhard-Zelinsky halogenation for the α-bromination of carboxylic acids to form the corresponding acyl bromide. It is also useful for the conversion of primary and secondary alcohols to alkyl bromides.
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使用
Phosphorus tribromide is used mainly for the conversion of alcohols to alkyl bromides and it is used in tests for skin corrosivity. It is used for alkene preparation and it act as a lewis base and a lewis acid. Phosphorus tribromide is used in the manufacture of pharmaceuticals such as alprazolam, methohexital and fenoprofen.
Phosphorus tribromide may be used as a reagent:
In a novel protocol for synthesizing 7-ethoxy-1-(p-ethylphenoxy)-3,7-dimethyl-2-octene, a synthetic juvenile hormone mimic of trans,trans,cis-10,11-epoxy-7-ethyl-3,11-dimethyltrideca-2,6-dienoate.
To synthesize 1,2,3-diazaphosphinane, 1,2,3-thiazaphosphinine and 1,2-azaphosphole bearing a chromone ring.
To synthesize 1-Bromoundec-1-ene from 10-undecen-1-ol.
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製造方法
Phosphorus tribromide, PBr3, is most conveniently prepared by reaction between liquid bromine and a solution of white phosphorus in PBr3. In most of its reactions, the tribromide resembles the trichloride although the former has been much less studied and in some cases the products seem to be more complex.
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反応性
Silyl phosphites such as (EtO)2POSiMe3 and (Et3SiO)3P are known. The latter compound can be prepared in 30% yield by reacting phosphorus tribromide with an organosilane in the presence of zinc chloride. Esters of the former type can be made by reaction.
3Et3SiO+PBr3–-(Et3SiO)3+3RBr
Et3SiONa+(EtO)2PCl–-(EtO)2POSiEt3+NaCl)
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一般的な説明
A colorless fuming liquid with a pungent odor. Corrosive to metals and tissue. Boiling point 347°F (175°C). Freezing point -40°F (-40°C).
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空気と水の反応
Fumes in air. Decomposed by water to form phosphoric acid and hydrobromic acid. Reaction with warm water is very rapid and may be violent [Mellor v.8. 1032 1940].
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反応プロフィール
Phosphorus tribromide reacts with oxidizing agents to generate heat and products that may be flammable, combustible, or otherwise reactive; the reactions may be violent. Forms complexes with potassium or sodium metal that explode when shocked. Drop wise addition to 3-phenylpropanol caused an explosion when stirring of the mixture was discontinued [Chem. Brit., 1974, 10, 101-102].
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健康ハザード
Inhalation causes severe irritation of nose, throat, and lungs. Ingestion causes burns of mouth and stomach. Contact with eyes or skin causes severe burns.
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安全性プロファイル
Probably highly toxic.
A corrosive irritant to the eyes, skin, and
mucous membranes. Wdl react with water,
steam, or acids to produce heat, toxic and
corrosive fumes. Violent reaction or ignition
with calcium hydroxide + sodium carbonate,
phenylpropanol, sulfuric acid, oleum,
fluorosulfuric acid, chlorosulfuric acid,
1,1,1 -tris(hydroxymethyl)methane, water,
potassium, sodium, RuO4. When heated to
decomposition it emits very toxic fumes of
Brand POx. See also PHOSPHIDES and
BROMIDES.
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純化方法
It is decomposed by moisture, it should be kept dry and is corrosive. Purify it by distillation through an efficient fractionating column [see Whitmore & Lux J Am Chem Soc 54 3451] in a slow stream of dry N2, i.e. under strictly dry conditions. [Gay & Maxson Inorg Synth II 147 1946, Org Synth Col Vol II 358 1943.] Dissolve it in CCl4, dry it over CaCl2, filter and distil it. Store it in sealed ampoules under N2 and keep it away from light. HARMFUL VAPOURS.
