臭化水素酸

外観

無色～わずかにうすい褐色, 澄明の液体

性質

臭化水素には腐食性や不燃性があります。密度は3.307g/L、融点は–86.80℃、沸点は–66.38℃です。

ハロゲン化水素の1つで、水素と臭素からなる化合物です。直線形の分子であり、化学式はHBrで、モル質量は80.912です。低温環境下で臭化水素は、水和物の結晶を形成します。

臭化水素はやなど酸素を有する有機溶媒に易溶です。水にもよく溶け、水溶液は強酸を示します。臭化水素の水溶液は臭化水素酸と呼ばれていて、47.63%の臭化水素酸は沸点124.3℃の共沸混合物です。

共沸混合物に近い48%程度が市販品として一般的で、医薬用外劇物の指定を受けています。水に対する溶解熱はΔH° = –85.15kJ/molであり、ハロゲン化水素の中で最大です。に性質がよく似た1価の強酸で、酸化されやすいです。

例えば、空気によって酸化したり、光によって分解して臭素を遊離したりすることで、黄色味を帯びることもあります。さらに、臭化水素の還元作用は、塩化水素 (HCl) よりも強力です。

溶解性

水, アルコール, エーテルに易溶。

反応

アルコールを用いたブロモアルカンの生成のために、臭化水素は利用されます。ブロモアルカンは、臭化水素のアルケンへの付加でも得ることが可能です。

アルキンに臭化水素を付加させるとブロモアルケンが生成し、通常立体化学はアンチ型 (英: anti form) です。ハロアルケンへの臭化水素の付加においては、マルコフニコフ則 (英: Markovnikov's rule) に従い、gem-ジハロアルカンが得られます。

その他、臭化水素はラクトンやエポキシドの開環反応だけでなく、ブロモアセタールの合成反応にも使用されます。多種多様な有機反応において、臭化水素は触媒として利用可能です。

解説

臭化水素酸,無色の強い酸でやや還元性がある．水との共沸混合物の組成は47.63％ で，124.3 ℃ で沸騰する．もっとも濃厚なものは臭化水素を82％ 含み，その組成はおよそ(HBr ＋ H2O)に相当する．臭素は三臭化物イオン，五臭化物イオンとなり，大量に溶解する．多くの金属と水素を発生して反応し，臭化物となる．また，酸化物，過酸化物，塩素により酸化されて臭素を遊離する．光，空気によって分解され，臭素を遊離する．

森北出版「化学辞典（第2版）

用途

汎用試薬。

用途

ブロム塩類、ブロムアルキルの製造原料

用途

各種臭化物塩類、臭化アルキルの原料。触媒。

用途

各種ブロム塩類の製造(臭化カリ、臭化ナトリウム、臭化リチウム、臭化カルシウムなど)、各種臭化アルキルの製造(臭化メチル、臭化エチル、臭化アリルなど)、ビタミン合成、鎮静剤など医薬品の合成

製造

臭化水素の水溶液．臭化水素の水への溶解，臭素水の水素，硫化水素，二酸化硫黄などによる還元，臭化カリウムの濃硫酸溶液の蒸留により得られる．

合成法

臭化水素は触媒を用いて、水素と臭素の反応によって生成します。臭化物とを反応させるか、と水の混合物に臭素を作用させることによって、臭化水素を得られます。

それ以外にも実験室規模では、さまざまな合成法があります。例えば、 (英: tetralin) の臭素化です。中においてトリフェニルホスホニウムブロミド (Ph₃PH⁺Br⁻) を還流して熱分解することで、無水の臭化水素を得ることもできます。

ただし、塩化水素や塩酸とは異なり、臭化水素や臭化水素酸の製造規模は小さいです。初期の製造法は200〜400℃ほどの高温で、水素と臭素を反応させていました。通常工業的な反応では、白金やアスベストを触媒として用います。

使用上の注意

空気及び光によって徐々に褐色を増す。

説明

Hydrobromic Acid is a strong acid formed by dissolving the diatomic molecule HBr in water. “Constant-boiling” hydrobromic acid is an aqueous solution that distills at 124.3°C and contains 47.6% HBr by weight. Hydrobromic acid has a pKa of 9, making it a stronger acid than hydrochloric acid, but not as strong as HI, hydroiodic acid. Hydrobromic acid is one of the strongest mineral acids known.
Hydrobromic acid is mainly used for the production of inorganic bromides, especially the bromides of zinc, calcium, and sodium. It is a useful reagent for generating organobromine compounds. Certain ethers are cleaved with HBr. It also catalyzes alkylation reactions and the extraction of certain ores. Industrially significant organic compounds prepared from hydrobromic acid include allyl bromide, tetrabromobis(phenol), and bromoacetic acid. Hydrobromic acid can be prepared in the laboratory via the reaction of Br2, SO2 and water. Another laboratory preparation involves the production of anhydrous HBr, which is then dissolved in water.
Hydrobromic acid has commonly been prepared industrially by reacting bromine with either sulfur or phosphorous and water. However, it can also be produced electrolytically. It can also be prepared by treating bromides with nonoxidizing acids like phosphoric or acetic acids. Hydrobromic acid is available commercially in various concentrations and purities.

化学的特性

colourless liquid with a strong irritating odour

物理的性質

Colorless gas; fumes in moist air; pungent acrid odor; nonflammable; heav-ier than air; density 2.71 (air=1.0); gas density 3.55 g/L at 25°C; liquefies at-66.4°C; solidifies at -86.8°C; critical temperature 89.8°C; critical pressure84.5 atm; highly soluble in water (saturated aqueous solution contains 66%HBr at 25°C); forms a constant-boiling azeotrope at 47.5% HBr in solution,boiling at 126°C at atmospheric pressure; soluble in alcohol; a 0.10Maqueoussolution is 93% ionized to H+and Br ? ions at 18°C.

使用

Hydrogen bromide is used as a reagent and catalyst in several types of organic reactions such as the formation of alkyl bromides from alcohols.
It is also used as a source material in the preparation of inorganic bromides. Hydrogen bromide serves as a catalyst in alkylation reactions. It has also been reportedly used in the controlled oxidation of aliphatic and alicyclic hydrocarbons to peroxides, ketones, and acids. In organic synthesis, hydrogen bromide is used to substitute bromine for aliphatic chlorine in the presence of aluminum catalyst.

製造方法

Hydrogen bromide gas may be produced by combustion of hydrogen inbromine vapor at 37.5°C using a catalyst such as platinized asbestos or pla-tinized silica gel. Unreacted free bromine is removed from the product bypassing the gaseous product mixture over hot activated charcoal. Hydrogenbromide formed may be absorbed in water to obtain the acid; or may be cooledand liquefied for shipment in cylinders.
Hydrobromic acid may be prepared in the laboratory by distillation of asolution of potassium bromide with dilute sulfuric acid:
2KBr + H₂SO₄ → K₂SO₄ + HBr
The acid may be prepared by several other methods, as well, including reac-tion of bromine either with sulfur and water; or with phosphorus and water:
2Br₂ + S + 2H₂O → 4HBr + SO₂
Hydrobromic acid also may be prepared by hydrogen exchange with a sodiumor potassium bromide solution when the solution is passed through a cation-exchange resin.
Hydrobromic acid is stored and shipped in drums, tanks, carboys, or bot-tles, labeled as corrosive materials. The anhydrous gas is stored and shippedin cylinders under its vapor pressure.

定義

Hydrogen bromide in aqueous solution.

一般的な説明

Hydrobromic acid solution (HBr) is a clear, yellow or brown colored liquid. Its reaction with K has been studied by a molecular beam technique.

空気と水の反応

Acrid odor, fumes in moist air forming clouds containing hydrobromic acid. Heat of solution large, [Merck, 11th ed., 1989].

反応プロフィール

HYDROGEN BROMIDE is an anhydrous (no water) strong acid. Reacts rapidly and exothermically with bases of all kinds (including amines and amides). Reacts exothermically with carbonates (including limestone and building materials containing limestone) and hydrogen carbonates to generate carbon dioxide. Reacts with sulfides, carbides, borides, and phosphides to generate toxic or flammable gases. Reacts with many metals (including aluminum, zinc, calcium, magnesium, iron, tin and all of the alkali metals) to generate flammable hydrogen gas. Reacts violently with acetic anhydride, 2-aminoethanol, ammonium hydroxide, calcium phosphide, chlorosulfonic acid, 1,1-difluoroethylene, ethylenediamine, ethyleneimine, oleum, perchloric acid, b-propiolactone, propylene oxide, silver perchlorate/carbon tetrachloride mixture, sodium hydroxide, uranium(IV) phosphide, vinyl acetate, calcium carbide, rubidium carbide, cesium acetylide, rubidium acetylide, magnesium boride, mercury(II) sulfate, calcium phosphide, calcium carbide.

危険性

Toxic by inhalation, strong irritant to eyes and skin.

健康ハザード

Hydrobromic acid and hydrogen bromide gas are highly corrosive substances that can cause severe burns upon contact with all body tissues. The aqueous acid and gas are strong eye irritants and lacrimators. Contact of concentrated hydrobromic acid or concentrated HBr vapor with the eyes may cause severe injury, resulting in permanent impairment of vision and possible blindness. Skin contact with the acid or HBr gas can produce severe burns. Ingestion can lead to severe burns of the mouth, throat, and gastrointestinal system and can be fatal. Inhalation of hydrogen bromide gas can cause extreme irritation and injury to the upper respiratory tract and lungs, and exposure to high concentrations may cause death. HBr gas is regarded as having adequate warning properties.
Hydrogen bromide has not been found to be carcinogenic or to show reproductive or developmental toxicity in humans.

火災危険

Behavior in Fire: Pressurized container may explode and release toxic, irritating vapor.

燃焼性と爆発性

Noncombustible, but contact with metals may produce highly flammable hydrogen gas.

使用用途

臭化水素は、医薬品や臭化水素酸、および各種臭化物の合成原料などとして用いられている他、汎用試薬としても利用されています。化学工業の分野においては、アルキル化触媒や還元剤として使用されています。

さらに、臭化水素には高品質のガスとしての用途もあり、エッチングガスやクリーニングガスとして利用可能です。臭化水素の水溶液である臭化水素酸は、ポリエステル繊維の原料であるの製造における触媒や各種ブロム塩類・臭化アルキルの原料として使用されており、重要な化学品です。 

材料の用途

Hydrogen bromide does not aggressively attack common metals of construction while in the anhydrous state. However, in the presence of moisture, hydrogen bromide will attack most metals except platinum and silver. Galvanized pipe, brass, and bronze should be avoided. Steel, Monel, and aluminum-silicon-bronze have proven satisfactory in anhydrous hydrogen bromide service.

概要

臭化水素とは、臭素と水素の化合物で、刺激臭をもつ無色の気体です。

法律上の名称はブロム水素で、空気中の湿気により、白煙を生じることも特徴です。臭化水素には毒性があり、眼や気管支の粘膜を侵し、呼吸困難を起こす恐れもあります。

貯蔵

Splash goggles and rubber gloves should be worn when handling this acid, and containers of HBr should be stored in a wellventilated location separated from incompatible metals. Water should never be added to HBr because splattering may result; always add acid to water. Containers of hydrobromic acid should be stored in secondary plastic trays to avoid corrosion of metal storage shelves due to drips or spills.
Cylinders of hydrogen bromide should be stored in cool, dry locations, separated from alkali metals and other incompatible substances.

純化方法

A solution of aqueous HBr ca 48% (w/w, constant boiling) is purified by distilling twice with a little red phosphorus, and the middle half of the distillate is taken. (The azeotrope at 760mm contains 47.8% (w/w) HBr.) [Hetzer et al. J Phys Chem 66 1423 1962]. Free bromine can be removed by Irvine and Wilson's method for HI (see above), except that the column is regenerated by washing with an ethanolic solution of aniline or styrene. Hydrobromic acid can also be purified by aerating with H2S, distilling and collecting the fraction boiling at 125-127o. [Heisig & Andur Inorg Synth I 155 1939.] HARMFUL VAPOURS.

不和合性

Hydrobromic acid and hydrogen bromide react violently with many metals with the generation of highly flammable hydrogen gas, which may explode. Reaction with oxidizers such as permanganates, chlorates, chlorites, and hypochlorites may produce chlorine or bromine.

廃棄物の処理

In many localities, hydrobromic acid or the residue from a spill may be disposed of down the drain after appropriate dilution and neutralization. Otherwise, hydrobromic acid and waste material containing this substance should be placed in an appropriate container, clearly labeled, and handled according to your institution's waste disposal guidelines. Excess hydrogen bromide in cylinders should be returned to the manufacturer. For more information on disposal procedures, see Chapter 7 of this volume.