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外観
無色澄明の液体
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種類
現在製品として市場に流通しているアセトアルデヒドは、研究開発用の試薬製品や、工業用有機合成の原料として販売されています。
試薬製品については、100mL , 500mL , 1L , 500gなど、実験室で取り扱いやすい容量の種類があります。沸点が低いことから冷蔵保管が必要な試薬です。
工業用薬品としては、14kgのキャニスター缶などの容量があります。大型容量で提供されていることが一般的です。
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性質
アセトアルデヒドは沸点が20.1℃と低い、揮発性の物質です。アセトアルデヒドには、ケト-エノール互変異性があります。すなわち、ビニルアルコールと平衡状態にありますが、常温における平衡定数は 6 × 10−5であることから、ほとんどはケト型の構造です。
引火点が-38 ℃と低いため引火性が高く、燃焼範囲は極めて広いとされます。また、空気と接触すると爆発性過酸化物を生成する可能性がある物質です。酸素、塩化コバルト、五酸化二窒素、塩素酸水銀、過塩素酸水銀、、との接触によっても爆発の恐れがあります。
微量の金属 (鉄) の存在下においては、酸、アルカリ性水酸化物の作用により重合する可能性がある物質です。更に、アセトアルデヒドは還元剤としての作用があるため、酸化剤、強酸、ハロゲン、アミンと激しく反応した場合に、火災や爆発の危険をもたらします。
以上の危険性から、消防法では、 第4類引火性液体、特殊引火物に定められています。その他にも、PRTR法、労働安全衛生法をはじめとする種々の法令で規制を受けている化合物です。
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溶解性
水, エタノール, エーテルに可溶。水、エタノール及びジエチルエーテルに極めて溶けやすい。
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解説
アセトアルデヒド，C2H4O(44.05)．CH3CHO．エタナール(ethanal)ともいう．工業的には，エテンを塩化パラジウム(Ⅱ)と塩化銅(Ⅱ)の水溶液を触媒として，空気または酸素で部分酸化して合成される(ヘキスト-ワッカー法)．以前はアセチレンを硫酸水銀の希硫酸溶液に通じて合成されたが，この触媒より生成するメチル水銀が，いわゆる水俣(みなまた)病の原因となった．刺激臭のある無色の液体．融点－121 ℃，沸点21 ℃．d204 0.7951．n20D 1.3316．酸化して酢酸，無水酢酸が合成され，アルドール縮合によりブチルアルデヒドを経てブチルアルコールが合成される．このほか，多数の有機工業薬品，プラスチック，染料，可塑剤などの合成原料として用いられる．
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用途
酢酸、有機薬品製造原料、防腐剤
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用途
酢酸エチル合成原料、ペンタエリスリトール?グリオキザール?ピリジン?ラクトニトリル?酢酸合成原料、防かび剤、防虫剤、薬品(写真現像用,医療用)、燃料配合剤、接着剤、NITE初期リスク評価書;酢酸エチル?グリオキサール?クロトンアルデヒド?ピリジン原料、防腐剤、溶剤、還元剤、医療用、SRI:CHEMICAL ECONOMICS HANDBOOK;有機中間原料、防腐剤、溶剤、還元剤、医療用 (化学工業日報社)
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製造
図2. アセトアルデヒドの工業的合成
アセトアルデヒドは、工業的にのワッカー酸化によって得られています。また、エタノールの酸化によっても製造されています。
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化学的特性
Acetaldehyde is a highly flammable, volatile, colorless liquid. It has a characteristic pungent and suffocating odor, and is miscible in water. Acetaldehyde is ubiquitous in the ambient environment. It is an intermediate product of higher plant respiration and formed as a product of incomplete wood combustion in fi replaces and woodstoves, burning of tobacco, vehicle exhaust fumes, coal refi ning, and waste processing. Exposures to acetaldehyde occur during the production of acetic acid and various other industrial chemical substances. For instance, the manufacture of drugs, dyes, explosives, disinfectants, pheno- lic and urea resins, rubber accelerators, and varnish.
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物理的性質
Colorless, mobile, fuming, volatile liquid or gas with a penetrating, pungent odor; fruity odor
when diluted. Odor threshold concentrations ranged from 1.5 ppbv (Nagata and Takeuchi, 1990) to
0.21 ppmv (Leonardos et al., 1969). Katz and Talbert (1930) reported an experimental detection
odor threshold concentration of 120 μg/m3 (67 ppbv). At low concentrations, acetaldehyde imparts
a pleasant, fruity, green apple or leafy green-like flavor (van Aardt et al., 2001). Twenty-five
panelists were randomly selected for testing milk products and water for determining flavor
thresholds. Flavor threshold concentrations determined by a geometric approach were 3,939 ppb
for nonfat milk (0.5% milk fat), 4,020 ppb for low-fat milk (2% milk fat), 4,040 ppb for whole
milk, 10,048 ppb for chocolate milk, and 167 ppb for spring water (van Aardt et al., 2001).
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天然物の起源
Reported.found.in.oak.and.tobacco.leaves;.in.the.fruital.aromas.of.pear,.apple,.raspberry,.strawberry.and.pineapple;.in.the.distillation.waters.of.Monarda punctata, orris,.cumin,.chenopodium;.in.the.essential.oils.of.Litsea cubeba, Magnolia grandiflora, Artemisia brevifolia, rosemary,.balm,.clary.sage,.Mentha arvensis, daffodil,.bitter.orange,.camphor,.angelica,.fennel,. mustard,.Scotch.blended.whiskey,.Japanese.whiskey,.rose.wine,.blackberry.brandy.and.rum.
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使用
Acetaldehyde is used as a general solvent in organic and polymer chemical reactions. It also plays a role in fruit and food quality, ripening and deterioration.manufacture of paraldehyde, acetic acid, butanol, perfumes, flavors, aniline dyes, plastics, synthetic rubber; silvering mirrors, hardening gelatin fibers. Flavoring agent in foods and beverages. Fumigant for storage of apples and strawberries.
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定義
ChEBI: Acetaldehyde is the aldehyde formed from acetic acid by reduction of the carboxy group. It is the most abundant carcinogen in tobacco smoke. It has a role as a human metabolite, an EC 3.5.1.4 (amidase) inhibitor, a carcinogenic agent, a mutagen, a teratogenic agent, an oxidising agent, an electron acceptor, a Saccharomyces cerevisiae metabolite, an Escherichia coli metabolite and a mouse metabolite.
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調製方法
The main production method is the Hoeschst–Wacker twostage
process, in which acetaldehyde is generated by oxidizing
ethylene with aqueous palladium chloride over a copper
catalyst. Some acetaldehyde is also produced by oxidation
of ethanol.
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一般的な説明
Acetaldehyde appears as a clear colorless liquid with a pungent choking odor. Flash point -36 °F. Boiling point 69 °F. Density 6.5 lb / gal. Vapors are heaver than air and irritate the mucous membranes and especially the eyes. Used to make other chemicals.
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空気と水の反応
Highly flammable. Easily oxidized by air to form unstable peroxides which may explode. Forms explosive mixture with air above 100°C (30-60% of the vapor in air) owing to formation of peroxyacetic acid [White, A. G. et al., J. Soc. Chem. Ind., 1950, 69, p. 206]. Soluble in water.
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反応プロフィール
Acetaldehyde undergoes a vigorously exothermic condensation reaction in contact with strong acids, bases or traces of metals. Can react vigorously with oxidizing reagents such as dinitrogen pentaoxide, hydrogen peroxide, oxygen, silver nitrate, etc. Contamination often leads either to reaction with the contaminant or polymerization, both with the evolution of heat. Can react violently with acid anhydrides, alcohols, ketones, phenols, ammonia, hydrogen cyanide, hydrogen sulfide, halogens, phosphorus, isocyanates, concentrated sulfuric acid, and aliphatic amines. Reactions with cobalt chloride, mercury(II) chlorate or perchlorate form sensitive, explosive products [Sax, 9th ed., 1996, p. 5]. An oxygenation reaction of Acetaldehyde in the presence of cobalt acetate at -20°C exploded violently when stirred. The event was ascribed to peroxyacetate formation [Phillips B. et al., J. Am. Chem. Soc., 1957, 79, p. 5982].
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健康ハザード
The acute toxicity of acetaldehyde is low by inhalation and moderate by ingestion. Exposure to acetaldehyde by inhalation is irritating to the respiratory tract and mucous membranes; this substance is a narcotic and can cause central nervous system depression. Ingestion of acetaldehyde may cause severe irritation of the digestive tract leading to nausea, vomiting, headache, and liver damage. Acetaldehyde causes irritation and burning upon skin contact and is a severe eye irritant.br Acetaldehyde has caused nasal tumors in rats exposed by inhalation and is listed by IARC in Group 2B ("possible human carcinogen"). It is not classified as a "select carcinogen" according to the criteria of the OSHA Laboratory Standard. Acetaldehyde is mutagenic and has been shown to be a reproductive toxin in animals. Acetaldehyde is formed by metabolism of ethanol, and chronic exposure can produce symptoms similar to alcoholism.
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火災危険
Acetaldehyde is a dangerous fire hazard (NFPA rating = 4) owing to its volatility and low autoignition temperature. Its vapor is explosive in the concentration range 4 to 66% in air and may be ignited by hot surfaces such as hot plates or light bulbs, or by static electricity discharges. The vapor is heavier than air and may travel a considerable distance to an ignition source and "flash back." Carbon dioxide or dry chemical extinguishers should be used to fight acetaldehyde fires.
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燃焼性と爆発性
Acetaldehyde is a dangerous fire hazard (NFPA rating = 4) owing to its volatility
and low autoignition temperature. Its vapor is explosive in the concentration range 4
to 66% in air and may be ignited by hot surfaces such as hot plates or light bulbs, or
by static electricity discharges. The vapor is heavier than air and may travel a
considerable distance to an ignition source and "flash back." Carbon dioxide or dry
chemical extinguishers should be used to fight acetaldehyde fires.
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化学反応
図3. アセトアルデヒドの化学反応
産業で用いられるアセトアルデヒドの大部分は、ティシチェンコ反応によるの工業的合成に用いられています。この反応では、アルコキシドを触媒として、アセトアルデヒド2分子がカルボン酸とアルコールとに不均化し、脱水縮合によって酢酸エチルが合成されます。
以前は酢酸の合成原料としても利用されてましたが、現在ではやからの直接合成の方が効率的であるため、あまり利用されなくなりました。
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使用用途
アセトアルデヒドの主な用途には、やアルデヒド類をはじめとする種々の有機化合物製造原料、防かび剤、防腐剤、溶剤、写真現像用薬品、燃料配合剤、還元剤、医療用薬品などがあります。
合成原料としては、ペンタエリスリトール・・グリオキザール・・ラクトニトリル・酢酸などの合成に用いられています。
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と人体
独特の臭気と刺激性を持ち、自動車の排気やたばこの煙、のなどに由来する大気汚染物質でもあります。アセトアルデヒドを大量に曝露することにより、発がんリスクが上昇するという有害性も報告されています。シックハウス症候群などの原因物質の一つです。
人体においては、エタノールを摂取した際に肝臓でアルコール脱水素酵素によって生成され、体内で生成したアセトアルデヒドは、アセトアルデヒド脱水素酵素によって、酢酸へと代謝されます。
アセトアルデヒドは、二日酔いの症状を引き起こすことで有名な物質です。アセトアルデヒドの代謝は、人種・体質によって生まれつき差異があり、飲酒に関係する体質はこれに由来しているとされます。
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接触アレルゲン
Acetaldehyde, as its metabolite, is responsible for many
of the effects of ethanol, such as hepatic or neurological
toxicity. A case of contact allergy was reported in
the textile industry, where dimethoxane was used as a
biocide agent in textiles, and its degradation led to
acetaldehyde
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安全性プロファイル
Confirmed carcinogen with experimental carcinogenic and tumorigenic data. Poison by intratracheal and intravenous routes. A human systemic irritant by inhalation. An experimental routes. A human systemic irritant by inhalation. An experimental teratogen. Other experimental reproductive effects. A skin and severe eye irritant. A narcotic. Human mutation data reported. A common air contaminant. Highly flammable liquid. Mixtures of 30-60% of the vapor in air ignite above 100℃. It can react violently with acid anhydrides, alcohols, ketones, phenols, NH3, HCN, H2S, halogens, P, isocyanates, strong alkalies, and amines. Reactions with cobalt chloride, mercury(Ⅱ) chlorate, or mercury(Ⅱ) perchlorate form violently in the presence of traces of metals or acids. Reaction with oxygen may lead to detonation. When heated to decomposition it emits acrid smoke and fumes.
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職業ばく露
Acetaldehyde is used as a chemical intermediate and can be found in many processed foods; in crafts, arts, automotive, and home improvement products
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発がん性
Acetaldehyde is reasonably anticipated to be a human carcinogenbased on sufficient evidence of carcinogenicity from studies in experimental animals.
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環境運命予測
Biological. Heukelekian and Rand (1955) reported a 5-d BOD value of 1.27 g/g that is 69.8% of
the ThOD value of 1.82 g/g.
Photolytic. Photooxidation of acetaldehyde in nitrogen oxide-free air using radiation between
2900 to 3500 ? yielded hydrogen peroxide, alkyl hydroperoxides, carbon monoxide, and lower
molecular weight aldehydes. In the presence of nitrogen oxides, photooxidation products include
ozone, hydrogen peroxide, and peroxyacyl nitrates (Kopczynski et al., 1974). Anticipated products
from the reaction of acetaldehyde with ozone or OH radicals in the atmosphere are formaldehyde
and carbon dioxide (Cupitt, 1980). Reacts with nitrogen dioxide forming peroxyacyl nitrates,
formaldehyde, and methyl nitrate (Altshuller, 1983). Irradiation in the presence of chlorine yielded peroxyacetic acid, carbon monoxide, and carbon dioxide (acetaldehyde into formic acid, methyl
nitrate, and peroxyacetal nitrate (Cox et al., 1980).
Chemical/Physical. Oxidation in air yields acetic acid (Windholz et al., 1983). In the presence
of sulfuric, hydrochloric, or phosphoric acids, polymerizes explosively forming trimeric
paraldehyde (Huntress and Mulliken, 1941; Patnaik, 1992). In an aqueous solution at 25 °C,
acetaldehyde is partially hydrated, i.e., 0.60 expressed as a mole fraction, forming a gem-diol (Bell
and McDougall, 1960). Acetaldehyde decomposes at temperatures greater than 400 °C, forming
carbon monoxide and methane (Patnaik, 1992).
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貯蔵
Acetaldehyde
should be used only in areas free of ignition sources, and quantities greater than 1
liter should be stored in tightly sealed metal containers in areas separate from
oxidizers. Acetaldehyde should always be stored under an inert atmosphere of
nitrogen or argon to prevent autoxidation.
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輸送方法
UN1088 Acetaldehyde, Hazard Class: 3; Labels: 3-Flammable liquid.
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純化方法
Acetaldehyde is usually purified by fractional distillation in a glass helices-packed column under dry N2, discarding the first portion of distillate. Or, it is shaken for 30minutes with NaHCO3, dried with CaSO4 and fractionally distilled at 760mm through a 70cm Vigreux column (p 11). The middle fraction is collected and further purified by standing for 2hours at 0o with a small amount of hydroquinone (free radical inhibitor), followed by distillation [Longfield & Walters J Am Chem Soc 77 810 1955]. [Beilstein 1 IV 3094.]
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不和合性
Reacts with air to form unstable peroxides which can explode. Contact with air causes acetaldehyde to chemically degrade to acetic acid. Strong oxidizers, acids, bases, alcohols, ammonia, amines, halogens, phenols, acid anhydrides, ketones, hydrogen cyanide, hydrogen sulfide. May dissolve rubber. Slightly corrosive to mild steel. May explode without warning when exposed to heat, dust, corrosives, or oxidizers.
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廃棄物の処理
Consult with environmental regulatory agencies for guidance on acceptable disposal practices. Generators of waste containing this contaminant (≥100 kg/mo) must conform with EPA regulations governing storage, transportation, treatment, and waste disposal. Incineration.
