Метанол

Описание

Метанол (метиловый спирт, древесный спирт, карбинол, метилгидрат, гидроксид метила)– это прозрачная, бесцветная, легковоспламеняющаяся жидкость с очень низкой температурой кипения. При очищении метиловый спирт теряет запах. Метанол хорошо растворяется в полярных растворителя, смешивается с водой в любых пропорциях. При растворении в воде между молекулами спирта и воды образовываются водородные связи. Наличие водородных связей между молекулами спиртов обуславливают относительно высокую в сравнении с углеводородами температуру кипения. 

Химические свойства

Прозрачная бесцветная жидкость.

Описание

Methyl alcohol, also known as methanol or wood alcohol, is a clear, colorless, flammable liquid that is the simplest alcohol.
World production of methanol is approximately 8.5 billion gallons annually. Methanol is produced industrially, starting with the production of synthesis gas or syngas. Syngas used in the production of methyl alcohol is a mixture of carbon monoxide and hydrogen formed when natural gas reacts with steam or oxygen. Methyl alcohol is then synthesized from carbon monoxide and hydrogen.
Methyl alcohol is poisonous and is commonly used to denature ethyl alcohol. Methanol poisoning results from ingestion, inhalation of methanol vapors, or absorption through the skin. Methanol is transformed in the body to formaldehyde (H2CO) by the enzyme alcohol dehydrogenase.The formaldehyde is then metabolized to formic acid (HCOOH)by aldehyde dehydrogenase.

Химические свойства

Methanol is a clear, water-white liquid with a mild odor at ambient temperatures.The air odor threshold for methanol has been reported as 100 ppm . Others have reported that 2000 or 5900 ppm methanol is barely detectable .

Физические свойства

Clear, colorless liquid with a characteristic alcoholic odor. Odor threshold concentrations ranged from 8.5 ppb_v (Nagata and Takeuchi, 1990) to 100.0 ppm_v (Leonardos et al., 1969). Experimentally determined detection and recognition odor threshold concentrations were 5.5 mg/m³ (4.2 ppm_v) and 69 mg/m³ (53 ppm_v), respectively (Hellman and Small, 1974).

История

It was first isolated in 1661 by the Irish chemist Robert Boyle (1627–1691) who prepared it by the destructive distillation of boxwood, giving it the name spirit of box, and the name wood alcohol is still used for methyl alcohol. Methyl alcohol is also called pyroxylic spirit; pyroxylic is a general term meaning distilled from wood and indicates that methyl alcohol is formed during pyrolysis of wood. The common name was derived in the mid-1800s. The name methyl denotes the single carbon alkane methane in which a hydrogen atom has been removed to give the methyl radical. The word alcohol is derived from Arabic al kuhul.

Использование

Methylalcohol, CH30H, also known as methanol or wood alcohol, is a colorless, toxic, flammable liquid with a boiling point of 64.6 °C(147 °F). The principal toxic effect is on the nervous system,particularly the retinae. Methyl alcoholis miscible in all proportions with water,ethyl alcohol, and ether. It burns with a light blue flame producing water and carbon dioxide. This vapor forms an explosive mixture(6.0 to 36.5% by volume) with air. Methyl alcohol is an important inexpensive raw material that is synthetically produced for the organic chemical industry. Nearly half of the methyl alcohol manufactured is used in the production of formaldehyde. Other uses of methyl alcohol are as an antifreeze and fuel for automobiles and as an intermediate in the production of synthetic protein.

Определение

ChEBI: Methanol is the primary alcohol that is the simplest aliphatic alcohol, comprising a methyl and an alcohol group. It has a role as an amphiprotic solvent, a fuel, a human metabolite, an Escherichia coli metabolite, a mouse metabolite and a Mycoplasma genitalium metabolite. It is an alkyl alcohol, a one-carbon compound, a volatile organic compound and a primary alcohol. It is a conjugate acid of a methoxide.

Методы производства

Modern industrial-scale methanol production is exclusively based on synthesis from pressurized mixtures of hydrogen, carbon monoxide, and carbon dioxide gases in the presence of catalysts. Based on production volume, methanol has become one of the largest commodity chemicals produced in the world.

Реакции

Methyl alcohol is a versatile material, reacting (1) with sodium metal, forming sodium methylate, sodium methoxide CH3ONa plus hydrogen gas, (2) with phosphorus chloride, bromide, iodide, forming methyl chloride, bromide, iodide, respectively, (3) with H2SO4 concentrated, forming dimethyl ether (CH3)2O, (4) with organic acids, warmed in the presence of H2SO4, forming esters, e.g., methyl acetate CH3COOCH3, [CAS: 79-20-9], methyl salicylate C6H4(OH)·COOCH3, possessing characteristic odors, (5) with magnesium methyl iodide in anhydrous ether (Grignard’s solution), forming methane as in the case of primary alcohols, (6) with calcium chloride, forming a solid addition compound 4CH3OH·CaCl2, which is decomposed by H2O, (7) with oxygen, in the presence of heated smooth copper or silver forming formaldehyde. The density of pure methyl alcohol is 0.792 at 20 °C compared with H2O at 4 °C (the corresponding figure for ethyl alcohol is 0.789), and the percentage of methyl alcohol present in a methyl alcohol-water solution may be determined from the density of the sample.

Применение

В органической химии метанол используется в качестве растворителя.
Метанол используется в газовой промышленности для борьбы с образованием гидратов (из-за низкой температуры замерзания и хорошей растворимости). В органическом синтезе метанол применяют для выпуска формальдегида, формалина, уксусной кислоты и ряда эфиров (например, МТБЭ и ДМЭ), изопрена и др.
Наибольшее его количество идёт на производство формальдегида, который используется для производства карбамидоформальдегидных и фенолформальдегидных смол. Значительные количества CH3OH используют в лакокрасочной промышленности для изготовления растворителей при производстве лаков. Кроме того, его применяют (ограниченно из-за гигроскопичности и отслаивания) как добавку к жидкому топливу для двигателей внутреннего сгорания.

Всемирная организация здравоохранения(ВОЗ)

Methanol has been subjected to abuse by consumption as a substitute for ethanol. Its toxic metabolites cause irreversible blindness and severe metabolic acidosis, and are ultimately fatal. Methanol continues to be used as an industrial solvent.

Токсичность

Класс опасности - III. По степени воздействия на организм человека – умеренно опасное вещество. Смертельная доза метанола при приеме внутрь равна 30 г, но тяжелое отравление, сопровождающееся слепотой, может быть вызвано 5-10 г. По запаху и вкусу метанол невозможно отличить от этилового спирта, что является причиной отравлений при употреблении алкоголя неизвестного происхождения (содержащего метанол вместо этанола). Предельно допустимая концентрация метанола в воздухе рабочей зоны равна 5 мг/м3.

Общее описание

A colorless fairly volatile liquid with a faintly sweet pungent odor like that of ethyl alcohol. Completely mixes with water. The vapors are slightly heavier than air and may travel some distance to a source of ignition and flash back. Any accumulation of vapors in confined spaces, such as buildings or sewers, may explode if ignited. Used to make chemicals, to remove water from automotive and aviation fuels, as a solvent for paints and plastics, and as an ingredient in a wide variety of products.

Профиль реактивности

Methanol reacts violently with acetyl bromide [Merck 11th ed. 1989]. Mixtures with concentrated sulfuric acid and concentrated hydrogen peroxide can cause explosions. Reacts with hypochlorous acid either in water solution or mixed water/carbon tetrachloride solution to give methyl hypochlorite, which decomposes in the cold and may explode on exposure to sunlight or heat. Gives the same product with chlorine. Can react explosively with isocyanates under basic conditions. The presence of an inert solvent mitigates this reaction [Wischmeyer 1969]. A violent exothermic reaction occurred between methyl alcohol and bromine in a mixing cylinder [MCA Case History 1863. 1972]. A flask of anhydrous lead perchlorate dissolved in Methanol exploded when Methanol was disturbed [J. Am. Chem. Soc. 52:2391. 1930]. P4O6 reacts violently with Methanol. (Thorpe, T. E. et al., J. Chem. Soc., 1890, 57, 569-573). Ethanol or Methanol can ignite on contact with a platinum-black catalyst. (Urben 1794).

Опасность

Flammable, dangerous fire risk. Explosive limits in air 6–36.5% by volume. Toxic by ingestion (causes blindness). Headache, eye damage, dizziness, and nausea.

Угроза здоровью

The acute toxicity of methanol by ingestion, inhalation, and skin contact is low. Ingestion of methanol or inhalation of high concentrations can produce headache, drowsiness, blurred vision, nausea, vomiting, blindness, and death. In humans, 60 to 250 mL is reported to be a lethal dose. Prolonged or repeated skin contact can cause irritation and inflammation; methanol can be absorbed through the skin in toxic amounts. Contact of methanol with the eyes can cause irritation and burns. Methanol is not considered to have adequate warning properties.
Methanol has not been found to be carcinogenic in humans. Information available is insufficient to characterize the reproductive hazard presented by methanol. In animal tests, the compound produced developmental effects only at levels that were maternally toxic; hence, it is not considered to be a highly significant hazard to the fetus. Tests in bacterial or mammalian cell cultures demonstrate no mutagenic activity

Пожароопасность

Behavior in Fire: Containers may explode.

Воспламеняемость и взрывоопасность

Methanol is a flammable liquid (NFPA rating = 3) that burns with an invisible flame in daylight; its vapor can travel a considerable distance to an ignition source and "flash back." Methanol-water mixtures will burn unless very dilute. Carbon dioxide or dry chemical extinguishers should be used for methanol fires.

Химическая реактивность

Reactivity with Water No reaction; Reactivity with Common Materials: No reaction; Stability During Transport: Stable; Neutralizing Agents for Acids and Caustics: Not pertinent; Polymerization:Not pertinent; Inhibitor of Polymerization: Not pertinent.

Получение

Технологии получения:
сухая перегонка древесины и лигнина;
термическое разложение солей муравьиной кислоты (восстановление альдегидов или карбоновых кислот с использованием сильных восстановителей - натрийборгидрида или литийалюминийгидрида);
синтез из метана через метилхлорид с последующим омылением;
неполное окисление метана и получение из синтез-газа.
Современный промышленный метод получения метанола - синтез из оксида углерода и водорода на медь-цинковом оксидном катализаторе при температуре -  250 °C, давление - 7 МПа ( 69,08 атм, 71,38 кгс/см²). 

хранилище

Methanol 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.

Перевозки

UN1230 Methanol, Hazard Class: 3; Labels: 3-Flammable liquid, 6.1-Poisonous material. (International)

Несовместимости

Methanol reacts violently with strong oxidizers, causing a fire and explosion hazard.

Утилизация отходов

Consult with environmental regulatory agencies for guidance on acceptable disposal practices. Generators of waste containing this contaminant (≥100 kg/mo) must conform to EPA regulations governing storage, transportation, treatment, and waste disposal. Incineration