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外観
無色澄明の液体
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溶解性
水及び多くの有機溶媒と任意の割合で混合する。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
ピリジン．アザベンゼンともいう．コールタール中に，その多数の同族体とともに，0.2％ 前後含まれている．骨油，タバコの煙のなかにも少量含まれる．無色，特有の臭いと苦味をもつ液体．融点－42 ℃，沸点115.5 ℃．d250.9779．nD201.5102．きわめて弱い塩基で，強酸と塩をつくる．pKa 5.19(25 ℃，水溶液)．吸湿性で水，エタノール，エーテル，そのほかの有機溶媒に易溶，また多くの有機化合物をよく溶かす．芳香族性をもつ安定な化合物で，硝酸や酸化クロム(Ⅵ)によって酸化されない．求電子置換はベンゼンの場合より起こりにくく，非常にはげしい条件でニトロ化，スルホン化，およびハロゲン置換を受ける．置換反応は主として3位(β位)で起こる．過酸化水素または過酸で酸化すればN-オキシドを生じる．ナトリウムアマルガムで還元すると飽和化合物としてピペリジンを生じる．第三級アミンの性質をもち，ハロゲン化アルキル(RX)を作用させるとハロゲン化アルキルピリジニウム[C5H5NR]＋ X－を生じるが，それを高温に熱すればアルキル基が2位または4位に転移する．ピリジンは求核置換を受けやすい．たとえば，アルキルリチウムまたはアリールリチウムを作用させると，2位にアルキルまたはアリール置換が起こる．同族体の合成には，ハンチ法やチチバビン法がある．ピリジンは化学工業において，塩基性溶剤として重要である(ゴム，塗料工業)．中枢神経を抑制し，皮膚および気管を刺激する．LD50 891 mg/kg(ラット，経口)．
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用途
医薬反応溶媒、無水金属塩の溶剤、界面活性剤原料、有機合成原料、抗菌剤ジンクピリチオン等の原料、医薬品合成溶剤、飼料添加剤原料、加硫促進剤原料、アルコール変性剤
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用途
分析用溶媒、有機合成用原料(医薬等)。
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用途
アミノ酸配列分析用溶媒。
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用途
溶剤、有機合成原料(医薬、界面活性剤、加硫促進剤、エタノールの変性。
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合成
ピリジンの合成法
ピリジンは沸点が115℃と高く、減圧除去することが困難な溶媒です。そのためピリジンを除去したい場合は、と混ぜて共沸させたり希塩酸を用いて分液することで水層に移したりするのがおすすめです。
ピリジンの合成法のひとつとして、「Hantzsch (ハンチュ) のピリジン合成法」が挙げられます。これは、2分子のβ-ケトエステルと1分子のアルデヒドに対してを作用させると得られるジヒドロピリジンを、によって酸化することでピリジンに誘導する合成法です。この方法を用いると、多置換ピリジン誘導体も合成することができます。
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使用上の注意
吸湿性あり。
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化学的特性
Pyridine is a weak base (pKa= 5.25); a 0.2 M solution has a pH of 8.5 (HSDB
1988). Its carbon atoms are deactivated towards electrophilic substitution. This is
especially true in acidic media, where salts form at the nitrogen. It does, however,
readily undergo nucleophilic substitution, preferentially at the C-2 and also at the
C-4 position (Jori et al 1983). Being a tertiary amine, pyridine reacts with
alkylating agents to form quaternary salts (Santodonato et al 1985). Because of its
reduced capacity to donate electrons, it is more resistant to oxidation than benzene.
Oxidation with peroxy acids forms pyridine N-oxide which is then capable of
undergoing electrophilic substitution (Jori et al 1983). Pyridine reacts violently
with a number of compounds, including nitric acid, sulfuric acid, maleic anhydride,
perchromate, beta-propiolactone and chlorosulfonic acid. Thermal decomposition
can liberate cyanides (Gehring 1983). Both the pyridinium ion and
pyridine itself are readily reduced to the commercially important compound,
piperidine (Jori et al 1983).
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物理的性質
Clear, colorless to pale yellow, flammable liquid with a sharp, penetrating, nauseating fish-like
odor. Odor threshold concentrations in water and air were 2 ppm (Buttery et al., 1988) and 21 ppbv
(Leonardos et al., 1969), respectively. Detection odor threshold concentrations of 0.74 mg/m3 (2.3
ppmv) and 6 mg/m3 (1.9 ppmv) were experimentally determined by Katz and Talbert (1930) and
Dravnieks (1974), respectively. Cometto-Mu?iz and Cain (1990) reported an average nasal
pungency threshold concentration of 1,275 ppmv.
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天然物の起源
Pyridine was discovered by Anderson in coal tar in 1846 (Windholz et al 1983). It is found in tobacco smoke (Vohl and Eulenberg 1871; Lehmann 1909) and roasted coffee (Bertrand and Weisweiller 1913). Pyridine is found in wood oil and in the leaves and roots of Atropa belladonna (HSDB 1988), and is also a component of creosote oil (Krone et al 1986). In nature, pyridine and its derivatives are commonly found as components of alkaloids, vitamins, and coenzymes.
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使用
Pyridine is used directly in the denaturation of alcohol (ACGIH 1986; HSDB 1989; NSC 1978) and as a solvent in paint and rubber preparation (ACGIH 1986; HSDB 1989; NSC 1978) and in research laboratories for functions such as extracting plant hormones (Santodonato et al. 1985). Half of the pyridine produced today is used as an intermediate in making various insecticides and herbicides for agricultural applications (ACGIH 1986; Harper et al. 1985; Santodonato et al. 1985). Approximately 20% goes into the production of piperidine (Harper et al. 1985; Santodonato et al. 1985) which is commercially significant in the preparation of chemicals used in rubber vulcanization and agriculture (NSC 1978). Pyridine is also used as an intermediate in the preparation of drugs (antihistamines, steroids, sulfa-type and other antibacterial agents) dyes, water repellents, and polycarbonate resins (ACGIH 1986; Harper et al. 1985; NSC 1978; Santodonato et al. 1985). Pyridine is also approved by the Food and Drug Administration (FDA) for use as a flavoring agent in the preparation of foods (Harper et al. 1985; HSDB 1989) .
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製造方法
Pyridine is produced either by isolation from natural sources such as coal, or through chemical synthesis (HSDB 1989). Pyridine is produced by the fractional distillation of coal-tar residues (HSDB 1989; NSC 1978; Santodonato et al. 1985) in which 1 ton of coal produces 0.07-0.21 pounds of pyridine bases of which 57% is pyridine (Santodonato et al, 1985). Synthetically produced pyridine is currently the more important source of pyridine for commercial uses (Santodonato et al. 1985). Small amounts of pyridine are synthesized from acetaldehyde, formaldehyde, and ammonia with a fluidized silica-alumina catalyst, followed by fractionation to isolate the pyridine (Harper et al. 1985; HSDB 1989; NSC 1978).
Pyridine is produced from natural sources by Crowley Tar Products of Stow, Ohio, and Oklahoma City, Oklahoma (Harper et al. 1985; HSDB 1989; SRI 1986, 1987, 1988). Pyridine is synthetically produced by two companies, the Nepera Chemical Co. of Harriman, New York and the Reilly Tar and Chemical Corporation of Indianapolis, Indiana (Harper et al. 1985; SRI 1986, 1987, 1988).
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定義
ChEBI: Pyridine is an azaarene comprising a benzene core in which one -CH group is replaced by a nitrogen atom. It is the parent compound of the class pyridines.The molecules have a hexagonal planar ring and are isoelectronic with benzene. Pyridine is an example of an aromatic heterocyclic compound, with the electrons in the carbon–carbon pi bonds and the lone pair of the nitrogen delocalized over the ring of atoms. The compound is extracted from coal tar and used as a solvent and as a raw material for organic synthesis.
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調製方法
Pyridine is produced from the gases obtained by the coking of coal and by direct
synthesis. The light-oil fraction of coal tar is treated with sulfuric acid to produce
water-soluble pyridine salts and then the pyridine bases are recovered from the
aqueous phase by sodium hydroxide or ammonia (Jori et al 1983). The majority of
U.S. production is through synthetic means. This process uses a vapor-phase
reaction of acetaldehyde, formaldehyde and ammonia, which yields a mixture of
pyridine and 3-methylpyridine (Santodonato et al 1985). The product ratio depends
on the relative amounts of acetaldehyde and formaldehyde. Added methanol
increases the yield. The U.S. production of pyridine was estimated at 32 to 47
million pounds in 1975 (Reinhardt and Brittelli 1981). Pyridine is commercially
available in technical, 2° and 1° grades, the latter two referring to their boiling
ranges. Major impurities are higher boiling homologues, such as picolines, lutidines
and collidines, which are mono-, di-, and trimethylpyridines (Santodonato et al
1985; Jori et al 1983).
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一般的な説明
A clear colorless to light yellow liquid with a penetrating nauseating odor. Density 0.978 g / cm3. Flash point 68°F. Vapors are heavier than air. Toxic by ingestion and inhalation. Combustion produces toxic oxides of nitrogen.
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空気と水の反応
Highly flammable. Soluble in water.
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反応プロフィール
Azabenzene is a base. Reacts exothermically with acids. During preparation of a complex of Azabenzene with chromium trioxide, an acid, the proportion of chromium trioxide was increased. Heating from this acid-base reaction led to an explosion and fire [MCA Case History 1284 1967]. A 0.1% solution of Azabenzene (or other tertiary amine) in maleic anhydride at 185°C gives an exothermic decomposition with rapid evolution of gas [Chem Eng. News 42(8); 41 1964]. Mixing Azabenzene in equal molar portions with any of the following substances in a closed container caused the temperature and pressure to increase: chlorosulfonic acid, nitric acid (70%), oleum, sulfuric acid (96%), or propiolactone [NFPA 1991]. The combination of iodine, Azabenzene, sulfur trioxide, and formamide developed a gas over pressurization after several months. This arose from the slow formation of sulfuric acid from external water, or from dehydration of the formamide to hydrogen cyanide. Ethylene oxide and SO2 can react violently in Azabenzene solution with pressurization if ethylene oxide is in excess (Nolan, 1983, Case History 51).
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危険性
Flammable, dangerous fire risk, explosive
limits in air 1.8–12.4%. Toxic by ingestion and inhalation. Skin irritant, liver and kidney damage.
Questionable carcinogen.
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健康ハザード
The acute toxicity of pyridine is low. Inhalation causes irritation of the respiratory
system and may affect the central nervous system, causing headache, nausea,
vomiting, dizziness, and nervousness. Pyridine irritates the eyes and skin and is
readily absorbed, leading to systemic effects. Ingestion of pyridine can result in liver
and kidney damage. Pyridine causes olfactory fatigue, and its odor does not provide
adequate warning of the presence of harmful concentrations.
Pyridine has not been found to be carcinogenic or to show reproductive or
developmental toxicity in humans. Chronic exposure to pyridine can result in
damage to the liver, kidneys, and central nervous system.
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燃焼性と爆発性
Pyridine is a highly flammable liquid (NFPA rating = 3), and its vapor can travel a
considerable distance and "flash back." Pyridine vapor forms explosive mixtures
with air at concentrations of 1.8 to 12.4% (by volume). Carbon dioxide or dry
chemical extinguishers should be used for pyridine fires.
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使用用途
ピリジンの主な使用用途には以下の例があります。
1. 求核剤
ピリジンの窒素原子には孤立電子対が存在するため、ピリジンは弱塩基性を示します。そのためピリジンは溶媒としてだけではなく求核剤としても利用することが可能です。
例として、を用いたアルコールのアセチル化が挙げられます。溶剤としてピリジンを用いることで、ピリジンが無水酢酸のカルボキシ基に求核攻撃します。その結果、酢酸イオンが脱離するとともに、求電子活性種であるN－アセチルピリジニウムイオンが発生します。これにより、アルコールの求核攻撃が促進され、円滑にアセチル化が進行します。
2. 医薬品原料
ピリジンは医薬品原料にも用いられます。例えば抗菌剤であるジンクピリチオンの原料として利用されており、塗料やシャンプーなどに混ぜ合わせることで防汚剤や殺菌剤として機能します。
他にも、鎮痛剤や無水金属塩の溶剤・反応媒介剤、医薬品原料、界面活性剤、飼料添加剤の原料、合成ゴムの加硫促進剤の原料などとして使われています。
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工業用途
Pyridine is a good solvent for a large number of compounds, both organic and
inorganic (Windholz et al 1983). About 50% of pyridine used in the U.S. is for the
production of agricultural chemicals, such as the herbicides paraquat, diquat and
triclopyr and the insecticide chlorpyrifos. Other uses are in the production of
piperidine; the manufacture of pharmaceuticals, such as steroids, vitamins and
antihistamines; and as a solvent. Solvent uses are found in both the pharmaceutical and polycarbonate resin industries. It is particularly useful as a solvent in processes
where HC1 is evolved (Santodonato et al 1985). Minor uses for pyridine are
for the denaturation of alcohol and antifreeze mixtures, as a dyeing assistant in
textiles and as a flavoring agent (Jori et al 1983; Furia 1968; HSDB 1988).
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接触アレルゲン
Pyridine (unsubstituted pyridine) and its derivative
(substituted pyridines) are widely used in chemistry.
Pyridine is a solvent used for many organic compounds
and anhydrous metallic salt chemicals. Contained in
Karl Fischer reagent, it induced contact dermatitis in a
laboratory technician. No cross-sensitivity is observed
between those different substances.
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安全性プロファイル
Poison by intraperitoneal route. Moderately toxic by ingestion, skin contact, intravenous, and subcutaneous routes. Mildly toxic by inhalation. A skin and severe eye irritant. Mutation data reported. Can cause central nervous system depression, gastrointestinal
upset, and liver and kidney damage. A flammable liquid and dangerous fire hazard when exposed to heat, flame, or oxidizers. Severe explosion hazard in the form of vapor when exposed to flame or spark. Reacts violently with chlorosulfonic acid, chromium trioxide, dinitrogen tetraoxide, HNO3, oleum, perchromates, ppropiolactone, AgClO4, H2SO4. Incandescent reaction with fluorine. Reacts to form pyrophoric or explosive products with bromine trifluoride, trifluoromethyl hypofluorite. Mixtures with formamide + iodine + sulfur trioxide are storage hazards, releasing carbon dioxide and sulfuric acid. Incompatible with oxidizing materials. Reacts with maleic anhydride (above 150°C) evolving carbon dioxide. To fight fire, use alcohol foam. When heated to decomposition it emits highly toxic fumes of NOx.
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職業ばく露
Pyridine is used as a solvent in
the chemical industry and as a denaturant for ethyl alco-
hol; as an intermediate in the production of pesticides;
in pharmaceuticals; in the manufacture of paints,
explosives, dyestuffs, rubber, vitamins, sulfa drugs; and
disinfectants.
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発がん性
Pyridine was not carcinogenic in
several chronic subcutaneous studies.
F344 rats were given pyridine orally in drinking water at
doses of 0, 7, 14, or 33 mg/kg for 2 years. The top dose
produced a decrease in body weights and water consumption.
Increased renal tubular adenoma or carcinoma and tubular
hyperplasia were observed in males at 33 mg/kg. Increased
mononuclear cell leukemia was observed in females at 14
and 33 mg/kg, which was considered equivocal in terms of
the relationship to pyridine exposure, since this is a common
finding in this strain of rat. Concentration-related nonneoplastic
change in the liver was seen at 33 mg/kg. Male
Wistar rats were similarly treated with doses of 0, 8, 17, or
36 mg/kg for 2 years. Decreased survival and body weights
were seen at 17 and 36 mg/kg. Increased testicular cell
adenomas were seen at 36 mg/kg. No changes in survival
or neoplasm rates in other tissues, including the kidney, were
reported although increased nephropathy and hepatic centrilobular
degeneration/necrosis was observed in some pyridine-
treated rats.
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特徴
ピリジンは無色透明な液体で、揮発性が高く特異臭があり吸湿性が強いです。水だけでなくアルコール、エーテル、ベンゼンなどの有機溶剤にも溶けます。
消防法では第4類第1石油類水溶性液体、PRTR法では第1種指定化学物質に該当します。保存の際は、遮光した容器で冷所かつ通気性が良い場所で保管するようにして下さい。
水生生物に非常に強い毒性があります。加水分解性を受ける結合がないため、一度自然界に排出されるとほとんど分解されず水中に蓄積してしまいます。廃棄する際は中和処理ののち地方自治体の指示に従ってください。
ピリジンは、人体に対しては皮膚や消化管、肺など様々な経路から吸収されますが、体内組織への蓄積は比較的起こりにくく、未反応の状態または代謝物として排泄されやすいです。ただし許容濃度をはるかに超えて曝露すると、中枢神経を抑制して皮膚および気管を刺激します意識の低下を引き起こすことがあるので、取り扱いには十分注意が必要です。
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環境運命予測
Biological. Heukelekian and Rand (1955) reported a 5-d BOD value of 1.31 g/g which is 58.7%
of the ThOD value of 2.23 g/g. A Nocardia sp. isolated from soil was capable of transforming
pyridine, in the presence of semicarbazide, into an intermediate product identified as succinic acid
semialdehyde (Shukla and Kaul, 1986). 1,4-Dihydropyridine, glutaric dialdehyde, glutaric acid
semialdehyde, and glutaric acid were identified as intermediate products when pyridine was
degraded by Nocardia strain Z1 (Watson and Cain, 1975).
Photolytic. Irradiation of an aqueous solution at 50 °C for 24 h resulted in a 23.06% yield of
carbon dioxide (Knoevenagel and Himmelreich, 1976).
Chemical/Physical. The gas-phase reaction of ozone with pyridine in synthetic air at 23 °C
yielded a nitrated salt having the formula: [C6H5NH]+NO3
- (Atkinson et al., 1987). Ozonation of
pyridine in aqueous solutions at 25 °C was studied with and without the addition of tert-butyl
alcohol (20 mM) as a radical scavenger. With tert-butyl alcohol, ozonation of pyridine yielded
mainly pyridine N-oxide (80% yield), which was very stable towards ozone. Without tert-butyl
alcohol, the heterocyclic ring is rapidly cleaved forming ammonia, nitrate, and the amidic
compound N-formyl oxamic acid (Andreozzi et al., 1991).
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貯蔵
Pyridine 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.
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輸送方法
UN1992 Flammable liquids, toxic, n.o.s., Hazard
Class: 3; Labels: 3-Flammable liquid, 6.1-Poisonous mate-
rials, Technical Name Required.
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不和合性
Violent reaction with strong oxidizers;
strong acids; chlorosulfonic acid; maleic anhydride; oleum
iodine.
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廃棄物の処理
Controlled incineration
whereby nitrogen oxides are removed from the effluent gas
by scrubber, catalytic or thermal devices .
