過塩素酸塩

外観

無色澄明の液体

性質

過塩素酸は、強酸性で使用条件によっては爆発するおそれがあるため、使用の際には注意が必要です。化学物質の有害性情報を示すGHS分類は次の通りです。

過塩素酸は加熱および有機物や還元剤との接触で爆発しやすいため、注意が必要です。有機物の分解作業中、爆発し、負傷する事故が過去に発生しています。試薬をこぼしてしまった場合は、大量の水で流すようにします。

過塩素酸は金属を腐食して水素を発生させます。保管はガラスやポリエチレン製の容器を使用し、直射日光を避け、換気の良いなるべく涼しい場所に常温で保管することが推奨されています。

溶解性

水に溶けやすい。

解説

過塩素酸，過塩素酸カリウムに濃硫酸を加えて真空蒸留すると得られる．無水状態で単離できる唯一の塩素の酸素酸で，無色の流動発煙性の液体．密度1.768 g cm－3(22 ℃)．融点－112 ℃，沸点7.5 kPa(56 Torr)で39 ℃．1 atm 下での蒸留では分解を伴う．無水物はきわめて分解しやすく，危険である．強い酸化力をもち有機物質とは爆発的に反応する．また，皮膚を腐食する．水に加えると発熱し，多くの水和物HClO4･nH2O(n ＝ 1，2，2.5，3，3.5)をつくる．市販品は60～70％ 水溶液である．熱時濃厚水溶液では酸化力が非常に強いが，冷時希薄水溶液では弱く安定である．水溶液は強い酸で多くの金属と水素を発生して反応し，過塩素酸塩を生じる．電解浴，電解研磨，過塩素酸塩の製造，酸化剤として用いられるほか，分析化学で試料の溶解，カリウムの分離定量試薬として用いられる．過塩素酸一水和物を過塩素酸オキソニウムといい，その結晶は[H3O]＋[ClO4－]の構造となっている．吸湿性固体．融点50 ℃，沸点110 ℃．

用途

火薬、爆薬、燃料、酸化剤

用途

大量の酸を用いる試料の前処理、高感度比色分析、高感度機器分析等。

用途

有害金属測定用試料の前処理。

用途

有機合成用触媒、メッキ用

用途

汎用試薬、有機及び無機合成用原料、過塩素酸塩の製造原料。

毒性

過塩素酸は高濃度では酸化力が非常に高く、有機物を腐食します。皮膚なども腐食するため、使用の際には保護手袋や保護メガネなど、保護具の着用が必須です。

また、呼吸器への刺激性があるため、局所排気装置下など換気の良い場所で使用する必要があります。

使用上の注意

70%水溶液である本品の酸化力はそれほど強くないが、加熱により濃縮されると強い酸化力が生じ、有機物等の還元剤と反応して爆発することがある。したがって有機物等の本品による加熱分解は特に注意を要する。

化学的特性

Perchloric acid, HCIO4, also known as Fraude's reagent,is a colorless, fuming,hygroscopic liquid that boils at 16°C(61OF). It is a strong oxidizer and is soluble in water. Cold dilute perchloric acid reacts with metals such as zinc and iron to yield hydrogen gas and the metallic perchlorate. Perchloric acid is used in electrolytic baths, electropolishing, explosives, analytical chemistry, and medicine.

物理的性質

Perchloric acid, HClO4, is a colorless liquid soluble in water. It is a strong acid comparable in strength to sulfuric and nitric acids. It is useful for preparing perchlorate salts, but it is also dangerously corrosive and readily forms explosive mixtures. Perchloric acid is produced by the treatment of sodium perchlorate with sulfuric acid and by the electrochemical oxidation of aqueous chlorine.

使用

Perchloric acid salts are used as explosivesand in metal plating. They are also used as anoxidizer and as a reagent in chemical analysis. These salts are produced by distillingpotassium chlorate with concentrated H2SO4under reduced pressure..

一般的な説明

A clear colorless odorless aqueous solution. Corrosive to metals and tissue. Closed containers may rupture violently under prolonged exposure to heat.

空気と水の反応

Water soluble with heat generation.

反応プロフィール

PERCHLORIC ACID is a solution of a strong oxidizing acid. May react vigorously or deflagrate when mixed with oxidizable material [Merck]. This includes (but is not limited to) alcohols, amines, boranes, dicyanogen, hydrazines, hydrocarbons, hydrogen, nitroalkanes, powdered metals, silanes, or thiols [Bretherick 1979. p.174]. Perchloric acid ignites on contact with sulfinyl chloride. (Bailar, 1973, Vol. 2, 1442).

健康ハザード

Perchloric acid is a highly corrosive substance that causes severe burns on contact with the eyes, skin, and mucous membranes. The acute toxicity of perchloric acid is moderate. This substance is a severe irritant to the eyes, mucous membranes, and upper respiratory tract. Perchlorates are irritants to the body wherever they contact it. Perchloric acid has not been shown to be carcinogenic or to show reproductive or developmental toxicity in humans

火災危険

Perchloric acid is noncombustible. The anhydrous (dehydrated) acid presents a serious explosion hazard. It is unstable and can decompose explosively at ordinary temperatures or in contact with many organic compounds.
Many heavy metal perchlorates and organic perchlorate salts are extremely sensitive explosives; the ammonium, alkali metal, and alkali earth perchlorates are somewhat less hazardous. Mixtures of perchlorates with many oxidizable substances are explosive.

燃焼性と爆発性

Perchloric acid is noncombustible. The anhydrous (dehydrated) acid presents a serious explosion hazard. It is unstable and can decompose explosively at ordinary temperatures or in contact with many organic compounds.
Many heavy metal perchlorates and organic perchlorate salts are extremely sensitive explosives; the ammonium, alkali metal, and alkali earth perchlorates are somewhat less hazardous. Mixtures of perchlorates with many oxidizable substances are explosive.

使用用途

過塩素酸の主な用途は、分析化学用試薬 (イオン交換クロマトグラフィーの溶離液など) 、金属・合金・鉱石などの溶解、有機合成用触媒、過塩素酸塩  (など) またはその誘導体の製造原料です。

そのほか、ロケットやミサイルの推進剤、エアバック、火薬、花火、マッチ、信号炎管、金属の電解研磨やエッチングなど工業的な用途もあります。

酸性度

過塩素酸はオキソ酸の1種で、塩素原子 (Cl) を含むオキソ酸の中では最も酸性度が高いです。塩素原子を含有するオキソ酸の酸性度の強さは次の通りです。

  HClO < HClO₂ < HClO₃ < HClO₄

酸素数が多いほど、酸素原子の有機効果が大きくなり、プロトン解離後の塩素酸イオンの安定性も高くなるため、酸性度も高くなります。過塩素酸のpKaは-10で、硝酸や硫酸と同様の強酸です。

概要

過塩素酸とは、化学式HClO₄で表されるハロゲン酸の1種です。

CAS登録番号は7601-90-3、分子量は100.46です。融点は-17℃の無色の発煙性液体で、強い酸化力を持ちます。常温では液体ですが、高濃度では危険性が高いので、一般的には60~70 %水溶液が市販されています。

環境運命予測

Perchloric acid, in the presence of moisture, forms the negatively charged perchlorate anion. The largest natural deposit of perchlorate is located in Chile; the origin of the deposit is not known.
Atmospheric perchlorate may be found near the sites where it is manufactured and the locations where it is used. Accidental spills of perchloric acid are another source of airborne perchlorate. Perchlorate has a low vapor pressure and is not found in the atmosphere as such; however, airborne particles are known to be a source of perchlorate. The particles may fall to the soil or be washed to the soil via rain. Soil particles containing perchlorate can migrate in air currents or with surface water or groundwater.
Perchlorate anions are highly mobile in groundwater because of their charged state and because they adsorb to soil particles poorly. Perchlorates in groundwater or surface water are extremely persistent. They are extremely stable under ambient conditions and tend not to react or degrade. Some types of anaerobic bacteria are known to biodegrade perchlorate; however, they are effective only under specific environmental conditions (high levels of organic carbon and low levels of oxygen and nitrate). Groundwater extraction is considered inefficient for the removal of perchlorate.
Plants exposed to perchlorate in the soil moisture can also take up perchlorate; some types of plants are known to concentrate perchlorate.

貯蔵

Splash goggles and rubber gloves should be worn when handling perchloric acid, and containers of the acid should be stored in a well-ventilated location separated from organic substances and other combustible materials. Work with >85% perchloric acid requires special precautions and should be carried out only by specially trained personnel.

純化方法

The 72% acid is been purified by double distillation from silver oxide under vacuum: this frees the acid from metal contamination. Distillation at atmospheric pressure is dangerous and explosive. The anhydrous acid is obtained by adding gradually 400-500mL of oleum (20% fuming H2SO4) to 100-120mL of 72% HClO4 in a reaction flask cooled in an ice-bath. The pressure is reduced to 1mm (or less), with the reaction mixture at 20-25o. The temperature is gradually raised during 2hours to 85o; the distillate is collected in a receiver cooled in Dry-ice. For further details of the distillation apparatus see Smith [J Am Chem Soc 75 184 1953]. It is HIGHLY EXPLOSIVE; a strong protective screen should be used at all times. [Schmeisser in Handbook of Preparative Inorganic Chemistry (Ed. Brauer) Academic Press Vol I pp 318-320 1963.]

不和合性

Cold 70% perchloric acid is a strong acid but is not considered to be a strong oxidizing agent; however, more concentrated solutions are good oxidizers. Temperature increases the oxidizing power of perchloric acid, and hot concentrated solutions are very dangerous. Evaporation of a spill of the 70% solution may lead to the formation of more dangerous concentrations. Reaction of 70% perchloric acid with cellulose materials such as wood, paper, and cotton can produce fires and explosions. Oxidizable organic compounds including alcohols, ketones, aldehydes, ethers, and dialkyl sulfoxides can react violently with concentrated perchloric acid. All perchlorates are potentially hazardous when in contact with reducing agents.

廃棄物の処理

Excess perchloric 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.