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性質
硫化カルボニルの融点は−138.8°Cで、沸点は−50.2°Cです。水分の存在下では、硫化水素と二酸化炭素に分解します。
1994年まで硫化カルボニルの毒性の情報は発表されていませんでした。1,000ppm以上の高濃度では、刺激や匂いを感じず、突然の痙攣や呼吸麻痺によって死亡します。ラットを用いた実験では、1,400ppmで90分、3,000ppmで9分で半数が死に至りました。その一方で、12ppmのような低濃度では、動物実験で心臓や肺に影響は12週間見られていません。
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解説
硫化カルボニル (英: carbonyl sulfide) とは、化学式がCOSで表される無機化合物です。
常温・常圧では、無色の比較的安定した液化ガスです。 (CO2) と (CS2) の中間的な性質を持っています。天然には、鉱泉や火山からの噴出ガス中にとともに存在します。
硫化カルボニルは、高圧ガス保安法で毒性および可燃性に該当しませんが、高濃度での吸入毒性は強いです。細菌に対しても殺菌効果を持つとされています。労働安全衛生法では名称等を表示すべき危険有害物です。
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発生
自然界で硫化カルボニルは、海底火山から放出されています。大気中に最も存在している硫黄化合物で、0.5ppb程度含まれています。硫化カルボニルは硫黄循環でも重要です。成層圏まで達した硫化カルボニルは、酸化して硫酸が生じます。地上では植物の光合成によって、海上では海水の加水分解によって、数年で分解可能です。
硫化カルボニルは星間物質や金星の大気にも見られます。チーズや野菜類にわずかに存在し、種子や穀物にも約0.05〜0.1mg/kg含まれています。
硫化カルボニルは合成ガスの代表的な硫黄系不純物です。大気中に放出される3分の1が人間活動で生じると考えられています。硫化カルボニルの人工的な発生源は、化学合成の中間体と二硫化炭素製造時の副産物です。ごみやプラスチックの焼却のほか、合成繊維やデンプンの製造などでも生じます。石炭火力発電所、自動車、石油精製、バイオマス燃料、焼き魚によっても生成します。
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用途
殺虫剤、医薬?除草剤原料 (化学工業日報社)
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構造
硫化カルボニルのモル質量は60.07g/molで、密度は2.51g/Lです。硫黄原子がカルボニル基に直線状に結合しています。C=O原子間距離は115.78pmで、C=S原子間距離は156.01pmです。
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合成法
1841年に初めて、硫化水素と二酸化炭素から硫化カルボニルが合成されました。1867年にカール・フォン・タン (英: Carl von Than) によって、硫化カルボニルの性質が解明されています。
硫黄と一酸化炭素の反応で、硫化カルボニルは生成します。実験室では硫酸チオシアン酸カリウムから合成可能ですが、副生成物の除去が必要です。塩酸溶液中でイソチオシアネートを加水分解しても、硫化カルボニルを合成できます。
参考文献
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化学的特性
Carbonyl sulfide is a colorless gas or cold liquid.
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天然物の起源
Carbonyl sulfide, COS, is now recognized as a component of the atmosphere at a tropospheric concentration of approximately 500 parts per trillion by volume, corresponding to a global burden of about 2.4 million tons. It is, therefore, a significant sulfur species in the atmosphere. It is possible that the HO• radicalinitiated oxidation of COS and carbon disulfide (CS2) would yield 8-12 million tons as S in atmospheric sulfur dioxide per year. Though this is a small yield compared to pollution sources, the HO•-initiated process could account for much of the SO2 burden in the remote troposphere.
Both COS and CS2 are oxidized in the atmosphere by reactions initiated by the hydroxyl radical. The initial reactions are
HO• + COS ® CO2 + HS• (11.10.1)
HO• + CS2 ® COS + HS• (11.10.2)
These reactions with hydroxyl radical initiate oxidation processes that occur through a series of atmospheric chemical reactions. The sulfur-containing products that are initially formed as shown by Reactions 11.10.1 and 11.10.2 undergo further reactions to sulfur dioxide and, eventually, to sulfate species.
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使用
carbonyl sulfide is use as a fumigant for durable commodities and structures was patented worldwide by Australia in 1992. It is effective on a wide range of pests, including the common stored product species at reasonable concentrations (less than 50 gm-3) and exposure times (1-5 days) . However, the egg stage of several insects showed tolerance to the fumigant. The other problems associated with the use of carbonyl sulfide include its high tainting odour on the treated products and reduction in the germination of seeds. Hydrogen sulphide, an impurity, present in fumigant product supply was reported to be responsible for the off-odour problem. Selective removal of hydrogen sulphide using absorbents like tertiary amine may solve the tainting issues with this fumigant.
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定義
ChEBI: A one-carbon compound in which the carbon atom is attached to an oxygen and a sulfur atom via double bonds.
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一般的な説明
CARBONYL SULFIDE is a colorless, poisonous, flammable gas with a distinct sulfide odor. The gas is toxic and narcotic in low concentrations and presents a moderate fire hazard. Under prolonged exposure to fire or intense heat the container may rupture violently or rocket. CARBONYL SULFIDE is used in the synthesis of organic thio compounds.
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空気と水の反応
Highly flammable.
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反応プロフィール
CARBONYL SULFIDE is expected to react with vigor with strong oxidants.
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危険性
Narcotic in high concentrations.
Flammable, explosive limits in air 12–28.5%.
Central nervous system impairment.
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健康ハザード
TOXIC; may be fatal if inhaled or absorbed through skin. Contact with gas or liquefied gas may cause burns, severe injury and/or frostbite. Fire will produce irritating, corrosive and/or toxic gases. Runoff from fire control may cause pollution.
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火災危険
Flammable; may be ignited by heat, sparks or flames. May form explosive mixtures with air. Vapors from liquefied gas are initially heavier than air and spread along ground. Vapors may travel to source of ignition and flash back. Some of these materials may react violently with water. Cylinders exposed to fire may vent and release toxic and flammable gas through pressure relief devices. Containers may explode when heated. Ruptured cylinders may rocket. Runoff may create fire or explosion hazard.
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使用用途
硫化カルボニルには殺菌効果があり、 殺虫剤、医薬・除草剤原料、農薬の中間原料として使用されています。
以前は小規模な実験用や炭酸アルキルの合成中間体等と使用用途が限られていました。しかし近年では、半導体多層レジスト工程でドライエッチングガスとして注目を集め、使用量は増加しています。とくに半導体製造拠点の多い、米国や台湾で需要が増加しています。
ユーリー-ミラーの実験 (英: Miller–Urey experiment) では、硫化カルボニルがアミノ酸からペプチドを合成するための触媒になると明らかになり、生命の起源に重要な役割を果たしていると報告されました。ユーリー-ミラーの実験とは、原始生命の進化の実験的検証の一つであり、化学進化説の最初の実証実験として知られています。
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安全性プロファイル
Poison by
intraperitoneal route. Mildly toxic by
inhalation. Narcotic in high concentration.
An irritant. May liberate highly toxic
hydrogen sulfide upon decomposition. A
very dangerous fire hazard and moderate
explosion hazard when exposed to heat or
flame. Can react vigorously with oxidizing
materials. To fight fire, stop flow of gas or
use CO2, dry chemical, or water spray.
When heated to decomposition it emits
toxic fumes of CO. See also CARBONYLS
and SULFIDES.
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職業ばく露
Carbon oxysulfide is an excellent source
of usable atomic sulfur, therefore, it can be used in various
chemical syntheses, such as the production of episulfides, alkenylthiols, and vinylicthiols. It is also used to make viscose
rayon. It is probable that the largest source of carbon oxysulfide is as a by-product from various organic syntheses and petrochemical processes. Carbon oxysulfide is always formed
when carbon, oxygen, and sulfur, or their compounds, such as
carbon monoxide; carbon disulfide, and sulfur dioxide, are
brought together at high temperatures. Hence, carbon, oxysulfide is formed as an impurity in various types of manufactured
gases and as a by-product in the manufacture of carbon disulfide. Carbon oxysulfide is also often present in refinery gases.
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環境運命予測
Toxicity from exposure to COS is likely the result of its
decomposition to CO2 and H2S. H2S inhibits respiration at the
cellular level, causing methemoglobinemia, which inhibits the
cytochrome oxidase system, causing cytotoxic anoxia. In one
study, rats treated with acetazolamide, an inhibitor of carbonic
anhydrase, showed lower blood levels of H2S following exposure
to COS and exhibited decreased toxicity. H2S is believed to
be primarily responsible for many of the reported adverse
effects associated with exposure to COS.
COS reacts readily with ammonia and primary amines to
form ammonium thiocarbamate and amine salts of monothiocarbamic
acid, respectively. Reaction with two primary
amines may result in the formation of H2S and linking of the
two amines via a carbonyl group reaction, suggesting considerable
potential for protein cross-linking by COS in vivo, and
this has been proposed as a mechanism to explain occupational
neuropathy observed with CS2, and predicted for COS.
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輸送方法
UN2204 Carbonyl sulfide, Hazard Class: 2.3;
Labels: 2.3-Poisonous gas, 2.1-Flammable gas, Inhalation
Hazard Zone C. It is a violation of transportation regulations to refill compressed gas cylinders without the express
written permission of the owner. Cylinders must be transported in a secure upright position, in a well-ventilated
truck. Protect cylinder and labels from physical damage.
The owner of the compressed gas cylinder is the only entity
allowed by federal law (49CFR) to transport and refill
them. It is a violation of transportation regulations to refill
compressed gas cylinders without the express written permission of the owner.
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純化方法
Purify the gas by scrubbing it through three consecutive fritted washing flasks containing conc NaOH at 0o (to remove HCN), and then through conc H2SO4 (to remove CS2) followed by a mixture of NaN3 and NaOH solution; or passed through traps containing saturated aqueous lead acetate, then through a column of anhydrous CaSO4. Then it is freeze-pumped repeatedly and distilled through a trap packed with glass wool and cooled to -130o (using an n-pentane slurry). It liquefies at 0o/12.5mm. Use stainless steel containers. The gas is stored over conc H2SO4. [Glemser in Handbook of Preparative Inorganic Chemistry (Ed. Brauer) Academic Press Vol I p 654 1963.] TOXIC
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不和合性
Carbon oxysulfide can form explosive
mixture with air. Incompatible with strong bases.
Incompatible with oxidizers (chlorates, nitrates, peroxides,
permanganates, perchlorates, chlorine, bromine, fluorine,
etc.); contact may cause fires or explosions. Keep away
from alkaline materials, strong bases, strong acids, oxoacids, epoxides.
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廃棄物の処理
Return refillable compressed
gas cylinders to supplier. Dissolve in a combustible solvent,
such as alcohol, benzene, etc. Burn in a furnace with afterburner and scrubber to remove SO2
.
