Пиридин химические свойства, назначение, производство
Химические свойства
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).
Физические свойства
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.
Вхождение
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.
Использование
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) .
Подготовка
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).
Определение
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.
Методы производства
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).
Общее описание
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.
Реакции воздуха и воды
Highly flammable. Soluble in water.
Профиль реактивности
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).
Опасность
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.
Угроза здоровью
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.
Воспламеняемость и взрывоопасность
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.
Промышленное использование
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).
Контактные аллергены
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.
Профиль безопасности
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.
Возможный контакт
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.
Описание
ПИРИДИН — азотистое гетероциклическое соединение; в составе молекул многих биологически активных соединений (витаминов PP и B6, никотина и др.) присутствует пиридиновый шестичленный цикл, содержащий один атом азота. Пиридин — бесцветная жидкость с резким неприятным запахом; смешивается с водой и органическими растворителями. Пиридин — слабое основание, дает соли с сильными минеральными кислотами, легко образует двойные соли и комплексные соединения.
Химические свойства
Пиридин проявляет качества слабых оснований, третичных аминов, ароматических соединений. Устойчив к воздействию окислителей и растворов щелочей, вступает в реакции с сильными неорганическими кислотами с образованием солей пиридиния. Взаимодействует с алкилгалогенидами, галогенидами металлов, пероксидными органическими соединениями, амидом натрия. Образует комплексные соединения с водой, оксидами серы, бромом.
Канцерогенность
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.
Экологическая судьба
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).
Применение
В органическом синтезе инсектицидов и фунгицидов, красителей, клеев, различных производных пиридина; в качестве сульфирующего агента, оснóвного катализатора.
В фармацевтике для получения лекарственных средств, например, сульфамидов.
В аналитической химии.
В качестве растворителя.
Добавляют в этанол и антифризы, чтобы неприятный запах отпугнул любителей дешевого алкоголя. Спирт с подобными добавками называется денатурированным.
В текстильной промышленности для окрашивания тканей.
Как сырье для производства пищевых и фармацевтических ароматизаторов.
В резиновой индустрии при изготовлении некоторых видов каучуков.
Для изготовления взрывчатых веществ.
хранилище
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.
Получение
Пиридин содержится в каменноугольной смоле (около 0,08 % по массе пиридина), продуктах сухой перегонки древесины, торфа, костей. Пиридин выделяют главным образом из каменноугольной смолы, синтезируют из ацетилена и синильной кислоты HCN, из ацетальдегида и аммиака NH3 и т. д.
Перевозки
UN1992 Flammable liquids, toxic, n.o.s., Hazard
Class: 3; Labels: 3-Flammable liquid, 6.1-Poisonous mate-
rials, Technical Name Required.
Несовместимости
Violent reaction with strong oxidizers;
strong acids; chlorosulfonic acid; maleic anhydride; oleum
iodine.
Утилизация отходов
Controlled incineration
whereby nitrogen oxides are removed from the effluent gas
by scrubber, catalytic or thermal devices .
Пиридин препаратная продукция и сырье
сырьё
препарат
4-BROMO-TETRAHYDROPYRAN
N-PHENYLISONICOTINAMIDE
2-AMINO-6-CHLORO-3,5-DICYANOPYRIDINE
П-толуолсульфонат пиридиния
ПАРАКВАТ ДИХЛОРИД
1-хлор-2-метилпропил хлорформиа
1,2,4-триазоло [4,3-а] пиридин-3 (2Н)-она
Пиразинкарбoнитрил
7-АЦЕТОКСИКУМАРИН
Phenylcarbamic acid propyl ester
5-ацетил-2-амино-4-метилтиазол
5-ACETAMIDONICOTINIC ACID
Бензил хлорацета
trans-Ferulic acid
2-АМИНО-4-МЕТИЛ-ХИНОЛИН-3-КАРБОНИТРИЛ
3-(Trifluoromethyl)pyrazole
3 - (трифторметокси) коричной кислоты
N-фенacилпиридиний бромид
4-фтор-N-метилбензиламин
5-METHYLPICOLINIC ACID
Indigosol Green Blue IBC
2,4-MESITYLENEDISULFONYL DICHLORIDE
17beta-Hydroxy-17-methylandrosta-4,9(11)-dien-3-one
2 - (2-н-Бутоксиэтокси) этилацета
Аллил метил карбoна
3,5-DIMETHOXYCINNAMIC ACID
4-Acetamido-2-chloropyridine
4-фторкоричную кислота
Гидрокортизон ацета
Methyl 2-Fluoroisonicotinate
5-ацетилтиофен-2-карбoнитрил
5-BROMO-2-FLUOROCINNAMIC ACID
4-NITROISOPHTHALIC ACID
3,5-диметокси-4-гидроксибензальдегид
2,4,5,6-тетраметилбензолдисульфонил дихлорид
Пиридин-3-сульфанил хлорид гидрохлорид
3-Methoxycinnamic acid
бутил N-фенилкарбамат
3-(3-МЕТИЛ-2-ТИЕНИЛ)АКРИЛОВАЯ КИСЛОТА
Vat Grey M