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外観
無色～うすい黄色透明液体
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性質
1. 物理的性質
フランはに似た臭いをもつ無色～透明黄色の液体です。融点は-84℃、沸点は31℃で、比重は0.91、屈折率は1.42です。・エーテル・石油エーテルに溶けやすく、水には実質的にほとんど溶けません。また、アルカリに対しては安定していますが、無機酸に対しては樹脂化します。
引火点は-31℃で、極めて高い引火性を有しており、液体及び蒸気の取り扱いには注意が必要です。労働安全衛生法では「危険物、引火性の物」に指定されています。また、消防法にて「第4類引火性液体」に指定されています。
2. 化学的性質
フランは芳香族化合物であり、化学的には比較的安定した構造を持ってますが、ベンゼン環などの6員環と比べると不安定で反応性が高いものです。酸化剤と反応して爆発性の高い過酸化物を生成することがあるため、扱いには注意が必要です。また、水と反応して、酸化反応を起こすことがあるため、水との接触を避ける必要があります。
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解説
フラン，マツの木から得られるタール中に存在する．フルフラールを酸化すると得られる2-フランカルボン酸を，加熱脱炭酸すると得られる．クロロホルム臭をもつ無色の液体．沸点32 ℃(10 kPa)．d19.440.9371．n20D1.4216．エタノール，エーテル，石油エーテルに易溶，水に微溶．アルカリには安定であるが，無機酸では樹脂化する．マツ材-塩酸反応で緑色を呈する．フラン誘導体は植物の精油成分として存在するものが多い．フランは芳香族性が比較的小さく，ジエン性が高いため，ディールス-アルダー反応を起こしやすい．ナトリウムアマルガムでは還元されないが，ニッケル触媒による水素添加により，テトラヒドロフランを生成する．カチオノイド試薬による置換反応はα位で起こりやすい．脱水剤の存在下にアンモニアあるいは硫化水素と加熱すると，それぞれピロール，チオフェンを生成する．蒸気は麻酔作用があるので注意を要する．ラットの致死濃度は30400 ppm．また，エーテルと同様に過酸化物を形成するので，蒸留には注意が必要である．
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用途
合成樹脂原料,有機合成原料,溶剤,洗浄剤
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合成
図3. パール・クノール合成
天然物として抽出される他、有機合成によってもフランを得ることができます。例えば、パール・クノール合成によって1, 4-ジカルボニル化合物を酸で加熱処理することで、脱水反応を伴ってフラン構造をもつ化合物を合成することができます。
フェイスト・べナリー フラン合成では、ハロカルボニル化合物とケトエステルの脱水縮合により、フラン誘導体を得ることができます。また、フルフラールの酸化によって得られる2-フランカルボン酸を加熱脱炭酸することによって生成されます。
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説明
Furan occurs naturally in oils distilled from rosin containing
pinewood. In addition, many natural foods contain the furan
ring structure and substituted furans may be formed through
cooking of simple carbohydrates. Furan is also found in
tobacco smoke as well as wood smoke and gas emissions from
gasoline and diesel engines. Furan has also been detected in
industrial effluents and can be emitted to the air from petroleum
refineries and coal-mining and gasification plants.
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化学的特性
Furan is a cyclic dienic ether stabilized by benzene-like resonance. Because of its conjugated unsaturation and heterocyclic atom, furan will undergo many types of reactions. It is, therefore, of interest as a chemical intermediate for pharmaceuticals, insecticides and fine chemicals. The heterocyclic oxygen atom in a ring with conjugated unsaturation gives furan a combination of ether, aromatic and olefinic characteristics. This polyfunctionality permits it to undergo a variety of reactions. Compared to benzene, the furan ring has greater reactivity, and is more susceptible to cleavage, thus resembling the vinyl ethers. Like the vinyl ethers, the furan ring is cleaved by aqueous acids. This reaction is accompanied by resinification .
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使用
Furan is a five-membered heterocyclic aromatic ring. Furan is used as a building block for the preparation of many heterocyclic compounds.
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定義
A heterocyclic liquid organic
compound. Its five-membered ring contains
four carbon atoms and one oxygen
atom. The structure is characteristic of
some monosaccharide sugars (furanoses).
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一般的な説明
Furan is a stable, colourless chemical liquid. It is highly flammable and forms explosive mixtures with air. It is incompatible with many other chemical substances, for example, strong oxidising agents, acids, peroxides, and oxygen. Furan is produced commercially by decarbonylation of furfural. It is used mainly in the production of tetrahydrofuran, thiophene, and pyrrole. It also occurs naturally in certain woods and during the combustion of coal and is found in engine exhausts, wood smoke, and tobacco smoke.
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空気と水の反応
Highly flammable. When uninhibited, Furan forms explosive peroxides on exposure to air. Insoluble in water.
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反応プロフィール
Furan is sensitive to heat and may turn brown upon standing. Furan may be light sensitive. When uninhibited, Furan forms explosive peroxides on exposure to air. Furan may react with oxidizers, acids, peroxides and oxygen. Furan resinifies on evaporation or when in contact with mineral acids, but Furan is stable in alkalis. .
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危険性
Flammable, dangerous fire risk, flammable
limits 2–24%, forms peroxides on exposure to air.
Absorbed by skin. Possible carcinogen.
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健康ハザード
The vapors are narcotic. Acute exposure to Furan by inhalation may involve both reversible and irreversible changes. Acute exposure by ingestion or skin absorption, as well as chronic exposure, are associated with high toxicity.
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火災危険
Very dangerous, upon exposure to heat or flame. Furan may form unstable peroxides on exposure to air. Contact with acids can initiate a violent, heat producing reaction. Avoid acids, oxidizing agents. Upon standing in air, Furan may form unstable peroxides.
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使用用途
フランは多くの複素環式化合物を合成するための中間体として利用されています。また、合成樹脂、溶剤、洗浄剤などの原料にも広く使用されています。
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安全性プロファイル
Confirmed carcinogen.
Poison by inhalation and intraperitoneal
routes. Moderately toxic by ingestion and
skin contact. Experimental reproductive
effects. A narcotic. Mutation data reported.
The exposure concentration limit of 10 ppm
together with its low boiling point requires
that adequate ventilation be provided in
areas where ths chemical is handled.
Contact with liquid must be avoided since
this chemical can be absorbed through the
skin. Washing thoroughly with soap and
water followed by prolonged rinsing should
be done immedlatelp after accidental
contact.
A very dangerous fire hazard when
exposed to heat or flame; can react with
oxidzing materials. Unstabdized, it may
form unstable peroxides on exposure to air and should always be tested before
ddlation. Washing with an aqueous
solution of ferrous sulfate slightly acidified
with sodum bisulfate will remove these
peroxides. Confirm by test. Contact with
acids can initiate a violent exothermic
reaction. Moderate explosion hazard when
exposed to flame. Furan's low bohg point
makes it easy to obtain explosive
concentrations of the vapor in inadequately
ventilated areas. To fight fire, use CO2, dr).
chemical. When heated to decomposition it
emits acrid smoke and irritating fumes. See
also PEROXIDES.
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職業ばく露
Furan is used as a chemical intermedi ate in the production of herbicides and pharmaceuticals; for
making tetrahydrofuran; in formation of lacquers; as a sol vent for resins in organic synthesis, especially for pyrrole,
thiophene.
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発がん性
Furan is reasonably anticipated to be a human carcinogen based on sufficient evidence of carcinogenicity from studies in experimental animals.
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環境運命予測
Furan may be released to the environment as a waste industrial
product or from unintentional or accidental releases. If released
to soil, it is expected to volatilize. If released to water, furan is not
expected to adsorb to suspended particles and sediment and is
likely to volatilize to ambient air. Sulfate-reducing bacteria can
degrade furan. However, under nonsulfate-reducing conditions,
biodegradation in soil and water is expected to be slow. In the
air, furan will exist as a vapor and will be subject to degradation
by reacting with hydroxyl radicals.
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輸送方法
UN2389 Furan, Hazard Class: 3; Labels:
3-Flammable liquid.
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純化方法
Shake it with aqueous 5% KOH, dry it with CaSO4 or Na2SO4, then distil it under nitrogen, from KOH or sodium, immediately before use. A trace of hydroquinone could be added as an inhibitor of oxidation. [Beilstein 17 H 27, 17 I 16, 17 II 34, 17/1 V 291.]
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不和合性
May form explosive mixture with air.
Incompatible with oxidizers (chlorates, nitrates, peroxides,
permanganates, perchlorates, chlorine, bromine, fluorine,
etc.); contact may cause fires or explosions. Keep away
from alkaline materials, strong acids, amines, strong bases,
reducing agents. Unless stabilized with an inhibitor, air
exposure forms unstable peroxides.
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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 govern ing storage, transportation, treatment, and waste disposal.
