ジヒドリド硫黄

性質

硫化水素の化学式はH₂Sで分子量は34.082で、常温で無色の気体で空気に対する比重は1.1905です。融点は-85.5℃、沸点は-60.7℃、発火点は260℃、可燃性で引火性のある気体で、加熱すると約400℃で分解し始め、水素と硫黄に分かれます。

水にはよく溶け、弱酸性の水溶液になります。硫化水素の水溶液は、不安定な性質をもち、酸化すると硫黄を析出して白く濁ります。硫化水素は、天然にも存在し、火山ガスや温泉、鉱泉、原油、天然ガス等の中に含まれるほか、下水処理場、ごみ処理場でも硫黄が嫌気性細菌によって還元され、硫化水素が発生します。

動物や植物のタンパク質の腐敗によっても発生します。また、飲食店の厨房排水が流れ込む分離槽や溜め枡内で、水が滞留する場所があると発生します。さらに、糞や屁にも若干の硫化水素が含まれ、口臭にも関係しています。

硫化水素を空気中で点火すると、青色の炎を出して燃え、 (亜硫酸ガス) と水を生じます。(2H₂S + 3O₂ → 2SO₂ + 2H₂O)

解説

硫化水素，リュウカスイソ，体系名はスルファン．通常は硫化水素ないし硫化二水素とよぶ．室温では特異な腐卵臭をもつ無色の気体．天然に，火山ガス，鉱泉・温泉水，原油・天然ガスなどに含まれる．また，動物，植物のタンパク質の腐敗により発生する．実験室では，硫化鉄(Ⅱ)と希塩酸との反応でつくることが多かったが，この製法では各種不純物が含まれるので，市販のH2Sのボンベを使うことが多い．工業的には，硫黄蒸気と水素との高温触媒下での反応でもつくりうるが，いまは天然ガス，石油精製，工業排気ガスなどからの回収が主である．気体はH-S-Hの折れ線形で，∠H-S-H92°(液体では90°)，H-S1.35 Å．融点－85.5 ℃，沸点－60.7 ℃．密度0.993 g cm－3(－60 ℃)．1 g のH2Sは20 ℃ で242 cm3 の水に溶ける(CO2の約2倍)．水溶液は弱酸で，pK1 7.02，pK2 13.9．加熱すると，約400 ℃ で分解しはじめ，1700 ℃ で完全に H2 とSに分かれる．空気中で点火すると青い炎をあげて燃え，SO2とH2Oを生じる．水溶液は不安定で，空気酸化を受けて硫黄を析出して白濁する．金属，金属酸化物，金属塩などと反応して硫化物をつくる．単体ハロゲン(Cl2 など)とも反応する．硫黄・硫酸の主要製造原料，化学薬品などの製造工程で使用(医薬品，工業薬品，蛍光体，重水など)，金属の分離精製，HCl，H2SO4などからの金属除去，分析用試薬など広い用途がある．きわめて可燃性・引火性が高い．中枢神経系，心臓血管系，呼吸器系に障害もたらす，HCNに匹敵する強い毒性をもつ．空気中に0.1 ppm 存在しても検知できる強い悪臭をもつが，120 ppm で嗅覚麻ひが起こり，800～1000 ppm では一呼吸で死亡する．労働安全衛生法・名称等を通知すべき危険物及び有害物．大気汚染防止法特定物質．

用途

分析試験(金属沈殿剤)、金属の精製、各種工業薬品、農薬、医薬品の製造、蛍光体(夜光、蛍光染料)、エレクトロルミネッセンス(面照明)、フォトコンダクター(光電リレー露光計)製造、溶剤製造(DMSO、高級メルカプタン)、皮革処理(脱毛剤)

危険性

硫化水素の危険性

硫化水素は、可燃性や引火性が非常に高く、消防面での危険性が高いだけではなく、中枢神経系や呼吸器系等に障害をもたらすなど、強い毒性をもつため、取り扱いには注意が必要です。労働安全衛生法の特定化学物質の第二類物質に指定されています。

硫化水素は高濃度で吸入すると、即死するほどの猛毒です。腐卵臭が硫化水素の特徴ですが、20ppmを超えると嗅覚が麻痺して臭いを感じなくなるため、臭いで濃度確認はできません。この濃度のガスを吸入すると気管支炎、肺炎、肺水腫を起こす可能性があります。

また、100ppmの蒸気を長時間にわたって吸い続けると、生命を落とす可能性が出てきます。700ppmでは脳神経に作用して、意識障害、呼吸麻痺、死亡の可能性、5,000ppmを超えると即死の可能性が出てきます。

説明

Hydrogen Sulfide is a colorless, very poisonous, flammable gas with the characteristic foul odor of rotten eggs. It often results from the bacterial breakdown of organic matter in the absence of oxygen, such as in swamps and sewers where anaerobic digestion can take place. It also occurs in volcanic gases, “natural gas”, and some well waters. Hydrogen sulfide has numerous names, some of which are archaic.
Small amounts of hydrogen sulfide occur in crude oil, but natural gas can contain up to 90%. About 10% of the total global emission of H2S is due to human activity.

化学的特性

Hydrogen sulfide is a colourless gas with strong odour of rotten eggs (odour threshold ca 0.2 ppt).

物理的性質

H2S is soluble in carbon disulfide, methanol, acetone and alkanolamines. A solution of hydrogen sulfide in water is initially clear but over time turns cloudy. This is due to the slow reaction of hydrogen sulfide with the oxygen dissolved in water, yielding elemental sulfur, which precipitates out.

天然物の起源

Reported found in heated French beans, beef broth, vapors of canned beef, canned beef, beef extract, heated beef fat, raw beef, beer, bread, heated Brussels sprouts, cabbage, cooked celery, cheddar cheese, cooked and raw chicken, chives, heated coconut, codfish, ground and roast coffee, heated corn, heated egg, grapefruit juice, cooked herring, citrus juices, strawberry, cabbage, onion, potato, rutabaga, tomato, blue cheese, buttermilk, raw and boiled eggs, coffee, potato chips, rice, soybeans, okra, sweet corn, sake, squid, shrimps, cooked, fatty fish and other natural sources

来歴

Hydrogen sulfide is a colorless, flammable, toxic gas with the characteristic odor of rotten eggs.It is produced naturally from the anaerobic bacterial decomposition of organic wastes, occurs in volcanic gases and hot springs, is a product of animal digestion, and is generated in industrial processes. Hydrogen is a natural component of natural gas and petroleum; it is only a small fraction of oil (hundreds of ppm), but may form an appreciable component of natural gas. Natural gas typically contains up to 5% hydrogen sulfide. Natural gas is considered sour if the hydrogen sulfide content exceeds 5.7 mg of H2S per cubic meter of natural gas. The process for removing hydrogen sulfide from sour gas is referred to as sweetening the gas. Because hydrogen sulfide is associated with anaerobic respiration in sewers and swamps, it is referred to as sewer gas, swamp gas, or stink damp.

使用

Hydrogen sulfide is used as an analyticalreagent and in the manufacture of heavywater. It occurs in natural gas and sewer gas.It is formed by the reaction of a metal sulfidewith dilute mineral acid, and in petroleumrefining.

定義

ChEBI: A sulfur hydride consisting of s single sulfur atom bonded to two hydrogen atoms. A highly poisonous, flammable gas with a characteristic odour of rotten eggs, it is often produced by bacterial decomposition of organic matter in the absence of oxygen.

調製方法

Hydrogen sulfide is produced during anaerobic respiration (fermentation). Anaerobic respirationenables organisms, primarily bacteria and other microbes, to meet their energy needsusing sulfate, elemental sulfur, and sulfur compounds as electron acceptors instead of oxygen.

製造方法

By far the largest industrial route toH2S occurs in petroleum refineries. The “hydrodesulfurization” process liberates sulfur from petroleum by the action of hydrogen. The resulting H2S is converted to elemental sulfur by partial combustion via the Claus process that is a major source of elemental sulfur (In the Claus process, hydrogen sulfide is catalytically reacted with oxygen from the air to produce sulfur and sulfur dioxide). Other anthropogenic sources of hydrogen sulfide include coke ovens, paper-mills (using the sulfate method), and tanneries, where Na2S is used for processing cowhide to form leather. H2S arises from virtually anywhere where elemental sulfur comes in contact with organic material, especially at high temperatures.

反応性

Fluorine, chlorine, bromine, and iodine react with H2S to form the corresponding halogen acid. Metal sulfides are formed when H2S is passed into solutions of the heavy metals, such as Ag, Pb, Cu, and Mn. This reaction is responsible for the tarnishing of Ag and is the basis for the separation of these metals in classical wet qualitative analytical methods. Hydrogen sulfide reacts with many organic compounds.

工業製造

工業的には触媒の存在下、硫黄蒸気と高温で水素と反応させるか、硫化水素を含む副生ガス、天然ガスなどから回収する。ボンベ入りで市販されている（ボンベの色はねずみ色）。実験室では、キップの装置を用いて硫化鉄に希塩酸または希硫酸を作用させてつくる。

FeS＋2HCl→H2S＋FeCl2

空気と水の反応

Highly flammable; a flame can very easily flash back to the source of leak. Soluble in water to a maximum of 0.4% by mass at room temperature .

反応プロフィール

HYDROGEN SULFIDE reacts as an acid and as a reducing agent. Explodes on contact with oxygen difluoride, bromine pentafluoride, chlorine trifluoride, dichlorine oxide, silver fulminate. May ignite and explode when exposed to powdered copper in oxygen [Mertz, V. et al., Ber., 1880, 13, p. 722]. May react similarly with other powdered metals. Ignites on contact with metal oxides and peroxides (barium peroxide, chromium trioxide, copper oxide, lead dioxide, manganese dioxide, nickel oxide, silver oxide, silver dioxide, thallium trioxide, sodium peroxide, mercury oxide, calcium oxide) [Mellor, 1947, vol. 10, p. 129, 141]. Ignites with silver bromate, lead(II) hypochlorite, copper chromate, nitric acid, lead(IV) oxide and rust. May ignite if passed through rusty iron pipes [Mee, A. J., School Sci. Rev., 1940, 22(85), p. 95]. Reacts exothermically with bases. The heat of the reaction with soda lime, sodium hydroxide, potassium hydroxide, barium hydroxide may lead to ignition or explosion of the unreacted portion in the presence of air / oxygen [Mellor, 1947, vol. 10, p. 140].

危険性

Highly flammable, dangerous fire risk, explosive limits in air 4.3–46%. Toxic by inhalation, strong irritant to eyes and mucous membranes.

健康ハザード

The acute toxicity of hydrogen sulfide by inhalation is moderate. A 5-min exposure to 800 ppm has resulted in death. Inhalation of 1000 to 2000 ppm may cause coma after a single breath. Exposure to lower concentrations may cause headache, dizziness, and upset stomach. Low concentrations of H2S (20 to 150 ppm) can cause eye irritation, which may be delayed in onset. Although the odor of hydrogen sulfide is detectable at very low concentrations, it rapidly causes olfactory fatigue at higher levels, and therefore is not considered to have adequate warning properties. Hydrogen sulfide has not been shown to be carcinogenic or to have reproductive or developmental effects in humans

火災危険

Compound is heavier than air and may travel a considerable distance to source of ignition and flash back. HYDROGEN SULFIDE forms explosive mixtures with air over a wide range. Also reacts explosively with bromine pentafluoride, chlorine trifluoride, nitrogen triiodide, nitrogen trichloride, oxygen difluoride, and phenyl diazonium chloride. When heated to decomposition, HYDROGEN SULFIDE emits highly toxic fumes of oxides of sulfur. Incompatible with many materials including strong oxidizers, metals, strong nitric acid, bromine pentafluoride, chlorine trifluoride, nitrogen triiodide, nitrogen trichloride, oxygen difluoride and phenyl diazonium chloride. Avoid physical damage to containers; sources of ignition; storage near nitric acid, strong oxidizing materials, and corrosive liquids or gases.

燃焼性と爆発性

Hydrogen sulfide is flammable in air in the range of 4.3 to 45.5% (NFPA rating = 4). Combustion products (sulfur oxides) are also toxic by inhalation. In the event of a hydrogen sulfide fire, stop the flow of gas if possible without risk of harmful exposure and let the fire burn itself out.

使用用途

硫化水素は、主に分子内に硫黄 (S) をもつ化学物質の製造工程で広く使用されています。例えば、メチルメルカプタン (CH₃SH) 、エチルメルカプタン (C₂H₅SH) 、メルカプト酢酸 (HS-CH₂-COOH) などの硫黄を含む有機化合物の合成です。

硫化水素を重金属塩の水溶液に通すと、有色の硫化物の沈殿を生じることから、金属イオンの定性分析の試薬としての用途もあります。また、有機合成の際に、還元剤として使用されます。

そのほか、化学分析の核磁気共鳴分析 (NMR) などで使用される重水 (D₂O) を通常の水から分離する用途もあります。

农业用途

Hydrogen sulphide (H₂S) is a colorless, poisonous, flammable gas with an odor of rotting eggs. It is found in cesspools and mines and is a by-product of decomposed substances containing sulphur. It is one of the gaseous end-products of the reduction of sulphate in highly degraded paddy fields. Hydrogen sulphide is also produced in the laboratory for use as an analytical reagent.

材料の用途

Dry hydrogen sulfide is satisfactorily handled under pressure at normal ambient temperatures in carbon steel or black iron piping. Carbon steels in wet applications are known to be subject to sulfide stress cracking and low- temperature brittle fracture under some conditions of temperature, stress, and pressure. While hydrogen sulfide itself is relatively noncorrosive to steel in many uses, factors such as impurities, pH, erosive conditions, and high thermal or mechanical stresses in the metal can cause severe corrosion problems. High-strength steels are subject to crack formation when exposed to hydrogen sulfide.

製造方法

硫化水素の製造方法

硫化水素は、工業的には天然ガス、石油精製、工業排気ガス等から得られます。また、硫黄とメタンを高温で反応させることで、硫化水素と二硫化炭素が生成されます。他にも硫黄と水素の反応でも硫化水素を得ることができます。

排ガス等からの分離
硫化水素を含む酸性ガスを、アルカリ性の水溶液に吸収させます。アミン系水溶液などが吸収液に用いられます。吸収した後に、再加熱を行うことで硫化水素の高濃度ガスが得られます。

二硫化炭素製造工程での副生
原料のメタンガスと硫黄を反応炉で反応させると、二硫化炭素と硫化水素の混合気体が生成されます。この反応は、高い反応率で生成物の二硫化炭素と硫化水素が得られます。その後、蒸留装置によって、二硫化炭素と硫化水素を分離します。

　　CH_{4 +} 4S → CS_{2 +} 2H₂S

硫黄と水素の反応
単体の硫黄に水素を添加し、触媒存在下で加熱反応させることで、高純度の硫化水素を得ることができます。

　　S + H₂ → H₂S

環境運命予測

Hydrogen sulfide is a colorless, flammable compressed liquid gas with a characteristic odor of rotten eggs. The solubility of hydrogen sulfide in water is 3980 mg l^-1 at 20 ℃ and it is soluble in certain polar organic solvents, notably methanol, acetone, propylene carbonate, sulfolane, tributyl phosphate, various glycols and glycol ethers, gasoline, kerosene, crude oil, and carbon disulfide. The calculated vapor pressure at 21.9 ℃ is 1929 Pa. Boiling point and melting point of the substance are ^-60.33 ℃ and^-85.49 ℃, respectively. Based on the estimated Henry’s law constant of 468 atm mol^-1 for hydrogen sulfide, volatilization from water and soil is high.

貯蔵

cylinders of hydrogen sulfide should be stored and used in a continuously ventilated gas cabinet or fume hood. Local fire codes should be reviewed for limitations on quantity and storage requirements.

純化方法

Wash it, then pass the gas through a train of tubes containing saturated Ba(OH)2 (2x), water (2x), and dilute HCl [Goates et al. J Am Chem Soc 73 707 1951]. It is available in gas cylinders. HIGHLY POISONOUS.

不和合性

Hydrogen sulfide is incompatible with strong oxidizers. It will attack many metals, forming sulfides. Liquid hydrogen sulfide will attack some forms of plastics, rubber, and coatings. H2S reacts violently with a variety of metal oxides, including the oxides of chromium, mercury, silver, lead, nickel, and iron.

廃棄物の処理

To respond to a release, use appropriate protective equipment and clothing. Positive pressure air-supplied respiratory protection is required. Close cylinder valve and ventilate area. Remove cylinder to a fume hood or remote area if it cannot be shut off. Disposal Excess hydrogen sulfide should be returned to the manufacturer, according to your institution's waste disposal guidelines. For more information on disposal procedures, see Chapter 7 of this volume.