Муравьиная кислота

Описание

Formic acid is a clear, colorless liquid with a pungent odor. Formic acid was first isolated from certain ants and was named after the Latin formica, meaning ant. It is made by the action of sulfuric acid on sodium formate, which is produced from carbon monoxide and sodium hydroxide. It is also produced as a by-product in the manufacture of other chemicals such as acetic acid.
It can be anticipated that use of formic acid will continuously increase as it replaces inorganic acids and has a potential role in new energy technology. Formic acid toxicity is of a special interest as the acid is the toxic metabolite of methanol.

Химические свойства

Formic acid, or methanoic acid, is the first member of the homologous series identified as fatty acids with the general formula RCOOH. Formic acid was obtained first from the red ant; itscommon name is derived from the family name for ants, Formicidae. This substance also occurs naturally in bees and wasps, and is presumed to be responsible for the "sting" of these insects. Formic acid has a pungent, penetrating odor. It may be synthesized from anhydrous sodium formate and concentrated H2S04 at low temperature followed by distillation.

Физические свойства

Clear, colorless, fuming liquid with a pungent, penetrating odor. Odor threshold concentration is 49 ppm (quoted, Amoore and Hautala, 1983). it is miscible in water, alcohol, ether, and glycerin, and is obtained by chemical synthesis or oxidation of methanol or formaldehyde.

Вхождение

Widespread in a large variety of plants; reported identifed in Cistus labdanum and the oil of Artemisia trans- iliensis; also found among the constituents of petit grain lemon and bitter orange essential oil; reported found in strawberry aroma Reported found in apple, sweet cherry, papaya, pear, raspberry, strawberry, peas, cheeses, breads, yogurt, milk, cream, buttermilk, raw fsh, cognac, rum, whiskey, cider, white wine, tea, coffee and roasted chicory root

История

Formic acid is taken from the Latin word forant, formica. Naturalists had observed the acrid vapor from ant hills for hundreds of years. One of the earliest descriptions of formic acid was reported in an extract of a letter written from John Wray (1627–1705) to the publisher of Philosophical Transactions published in 1670. Wray’s letter reported on “uncommon Observations and Experiments made with an Acid Juyce to be Found in Ants” and noted the acid was previously obtained by Samuel Fisher from the dry distillation of wood ants. Formic acid is found in stinging insects, plants, unripe fruit, foods, and muscle tissue. J?ns Jacob Berzelius (1779–1848) characterized formic acid in the early 19th century, and it wasfirst synthesized from hydrocyanic acid by Joseph Louis Gay-Lussac (1778–1850) at about the same time. A number of synthetic preparations of formic acid were found in the first half of the 19th century. Marcellin Berthelot (1827–1907) discovered a popular synthesis using oxalic acid and glycerin in 1856; he and several other chemists from his period found syntheses of formic acid by heating carbon monoxide in alkaline solutions.

Методы производства

Formic acid is manufactured as a by-product of the liquidphase oxidation of hydrocarbons to acetic acid. It is also produced by (a) treating sodium formate and sodium acid formate with sulfuric acid at low temperatures followed by distillation or (b) direct synthesis from water and CO2 under pressure and in the presence of catalysts.

Определение

ChEBI: Formic acid is the simplest carboxylic acid, containing a single carbon. Occurs naturally in various sources including the venom of bee and ant stings, and is a useful organic synthetic reagent. Principally used as a preservative and antibacterial agent in livestock feed. Induces severe metabolic acidosis and ocular injury in human subjects. It has a role as an antibacterial agent, a protic solvent, a metabolite, a solvent and an astringent. It is a conjugate acid of a formate.

Реакции

Formic acid solution reacts as follows: (1) with hydroxides, oxides, carbonates, to form formates, e.g., sodium formate, calcium formate, and with alcohols to form esters; (2) with silver of ammonio-silver nitrate to form metallic silver; (3) with ferric formate solution, upon heating, to form red precipitate of basic ferric formate; (4) with mercuric chloride solution to form mercurous chloride, white precipitate; and (5) with permanganate (in the presence of dilute H2SO4) to form CO2 and manganous salt solution. Formic acid causes painful wounds when it comes in contact with the skin. At 160 °C, formic acid yields CO2 plus H2. When sodium formate is heated in vacuum at 300 °C, H2 and sodium oxalate are formed. With concentrated H2SO4 heated, sodium formate, or other formate, or formic acid, yields carbon monoxide gas plus water. Sodium formate is made by heating NaOH and carbon monoxide under pressure at 210 °C.

Общее описание

Formic acid is the simplest carboxylic acid. Crystal structure study by single-crystal X-ray diffraction technique at -50°C has shown that it has an orthorhombic structure with space group Pna. The photodegradation of formic acid has been investigated using ab intio calculations and time-resolved Fourier transform infrared spectroscopy. Its utility as a fuel in direct fuel cells has been studied. The momentum distribution for its monomer have been evaluated by electron momentum spectroscopy (EMS).

Реакции воздуха и воды

Fumes in air. Soluble in water with release of heat.

Профиль реактивности

Formic acid reacts exothmerically with all bases, both organic (for example, the amines) and inorganic. Reacts with active metals to form gaseous hydrogen and a metal salt. Reacts with cyanide salts to generate gaseous hydrogen cyanide. Reacts with diazo compounds, dithiocarbamates, isocyanates, mercaptans, nitrides, and sulfides to generate flammable or toxic gases. Reacts with sulfites, nitrites, thiosulfates (to give H2S and SO3), dithionites (SO2), to generate flammable and/or toxic gases and heat. Reacts with carbonates and bicarbonates to generate carbon dioxide but still heat. Can be oxidized by strong oxidizing agents and reduced by strong reducing agents. These reactions generate heat. May initiate polymerization reactions or catalyze other chemical reactions. A mixture with furfuryl alcohol exploded [Chem. Eng. News 18:72(1940)].

Опасность

Corrosive to skin and tissue.

Пожароопасность

Special Hazards of Combustion Products: Toxic vapor generated in fires

Профиль безопасности

Poison by inhalation, intravenous, and intraperitoneal routes. Moderately toxic by ingestion. Mutation data reported. Corrosive. A skin and severe eye irritant. A substance migrating to food from packaging materials. Combustible liquid when exposed to heat or flame; can react vigorously with oxidizing materials. Explosive reaction with furfuryl alcohol, H202, T1(NO3)3*3H2O nitromethane, P2O5. To fight fire, use CO2, dry chemical, alcohol foam. When heated to decomposition it emits acrid smoke and irritating fumes.

Возможный контакт

Formic acid is a strong reducing agent and is used as a decalcifier. It is used in pharmaceuticals; in dyeing textiles and finishing color-fast wool; electroplat ing, coagulating latex rubber; regeneration old rubber, and dehairing, plumping, and tanning leather. It is also used in the manufacture of acetic acid, airplane dope; allyl alcohol; cellulose formate; phenolic resins; and oxalate; and it is used in the laundry, textile, insecticide, refrigeration, and paper industries; as well as in drug manufacture.

Описание

Муравьиная кислота (систематическое наименование: метановая кислота) HCOOH — органическое соединение, первый представитель в ряду насыщенных одноосновных карбоновых кислот. Зарегистрирована в качестве пищевой добавки под обозначением E236. Своё название муравьиная кислота получила потому, что впервые она была выделена в 1670 году английским натуралистом Джоном Рэйем из рыжих лесных муравьёв. В природе также обнаружена у пчёл, в крапиве, хвое. Соли и анионы муравьиной кислоты называются формиатами.

Химические свойства

При стандартных условиях муравьиная кислота представляет собой резко пахнущую бесцветную жидкость. Растворима в ацетоне, бензоле, глицерине, толуоле. Смешивается с водой, диэтиловым эфиром, этанолом.

Константа диссоциации: 1,772⋅10⁻⁴.

Применение

В основном, муравьиную кислоту используют как консервирующий и антибактериальный агент при заготовке корма. Муравьиная кислота замедляет процессы гниения и распада, поэтому сено и силос, обработанные муравьиной кислотой, дольше сохраняются. Муравьиная кислота также используется в протравном крашении шерсти, для борьбы с паразитами в пчеловодстве, как растворитель в некоторых химических реакциях.

В лабораториях используют разложение жидкой муравьиной кислоты под действием горячей концентрированной серной кислоты, либо пропуская муравьиную кислоту над оксидом фосфора P2O5, для получения монооксида углерода.

В медицине используется для приготовления растворов пермуравьиной кислоты («первомур», или рецептура «С-4» (смесь перекиси водорода и муравьиной кислоты)). Первомур используют в хирургии в качестве предоперационного антисептического средства, в фармацевтической промышленности для дезинфекции оборудования.

Производство

1.Побочный продукт в производстве уксусной кислоты жидкофазным окислением бутана.

2.Окисление метанола:

CH3OH → HCHO → HCOOH

3.Реакцией монооксида углерода с гидроксидом натрия:

NaOH + CO → HCOONa → (+H2SO4, −Na2SO4) HCOOH

Это основной промышленный метод, который осуществляют в две стадии: на первой стадии монооксид углерода под давлением 0,6—0,8 МПа пропускают через нагретый до 120—130 °C гидроксид натрия; на второй стадии проводят обработку формиата натрия серной кислотой и вакуумную перегонку продукта.

4.Разложением глицериновых эфиров щавелевой кислоты. Для этого нагревают безводный глицерин со щавелевой кислотой, при этом отгоняется вода и образуются щавелевые эфиры. При дальнейшем нагревании эфиры разлагаются, выделяя углекислый газ, при этом образуются муравьиные эфиры, которые после разложения водой дают муравьиную кислоту и глицерин.

Перевозки

UN1779 Formic acid, with>85% acid by mass, Hazard class: 8; Labels: 8-Corrosive material, 3-Flammable liquid

Методы очистки

Anhydrous formic acid can be obtained by direct fractional distillation under reduced pressure, the receiver being cooled in ice-water. The use of P2O5 or CaCl2 as dehydrating agents is unsatisfactory. Reagent grade 88% formic acid can be satisfactorily dried by refluxing with phthalic anhydride for 6hours and then distilling it. Alternatively, if it is left in contact with freshly prepared anhydrous CuSO4 for several days about one half of the water is removed from 88% formic acid; distillation then removes the remainder. Boric anhydride (prepared by melting boric acid in an oven at a high temperature, cooling in a desiccator, and powdering) is a suitable dehydrating agent for 98% formic acid; after prolonged stirring with the anhydride the formic acid is distilled under vacuum. Formic acid can be further purified by fractional crystallisation using partial freezing. [Beilstein 2 IV 3.]

Несовместимости

Vapors may form explosive mixture with air. A medium strong acid and a strong reducing agent. Violent reaction with oxidizers, furfuryl alcohol; hydrogen peroxide; nitromethane. Incompatible with strong acids; bases, ammonia, aliphatic amines; alkanolamines, isocya nates, alkylene oxides; epichlorohydrin. Decomposes on heating and on contact with strong acids forming carbon monoxide. Carbamates are incompatible with strong acids and bases, and especially incompatible with strong reducing agents such as hydrideds and active metals. Contact with active metals or nitrides form flammable gaseous hydrogen. Incompatible with strongly oxidizing acids, peroxides, and hydroperoxides. Attacks metals: aluminum, cast iron and steel; many plastics, rubber and coatings.

Утилизация отходов

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