Адипиновая кислота

Описание

Adipic acid is a crystalline powder with practically no odor. It has the lowest acidity of any of the acids commonly used in foods and has excellent buffering capacity in the range of pH 2.5 to 3.0. Like succinic and fumaric acid, adipic acid is practically nonhygroscopic. Its addition to foods imparts a smooth, tart taste. In grape-flavored products, it adds a lingering supplementary flavor and gives an excellent set to food powders containing gelatin. As a result, adipic acid has found a wide number of uses as an accidulant in dry powdered food mixtures, especially in those products having delicate flavors and where addition of tang to the flavor is undesirable.

Its aqueous solutions have the lowest acidity of any of the common food acids. For concentrations from 0.5 to 2.4 g/100 mL, the pH of its solution varies less than half a unit. Hence, it can be used as a buffering agent to maintain acidities within the range of 2.5 to 3.0. This is highly desirable in certain foods, yet the pH is low enough to inhibit the browning of most fruits and other foodstuffs.

Химические свойства

Adipic acid is the organic compound with the formula (CH₂)₄(COOH)₂. From the industrial perspective, it is the most important dicarboxylic acid: About 2.5 billion kilograms of this white crystalline powder are produced annually, mainly as a precursor for the production of nylon. Adipic acid otherwise rarely occurs in nature.

Физические свойства

Adipic acid is a straight-chain dicarboxylic acid that exists as a white crystalline compound at standard temperature and pressure. Adipic acid is one of the most important industrial chemicals and typically ranks in the top 10 in terms of volume used annually by the chemical industry.

Вхождение

Reported found as a minor constituent in butter, and has been found in other fats as a product of oxidative rancidity. It also occurs in beet juice, pork fat, guava fruit (Psidium guajava L.), papaya (Carica papaya L.) and raspberry (Rubus idaeus L.).

Использование

Adipic Acid is primarily used in the synthesis of nylon. It has been used as a reagent in the solid-state polymerization of nylon analogs.

Определение

ChEBI: An alpha,omega-dicarboxylic acid that is the 1,4-dicarboxy derivative of butane.

Подготовка

Adipic acid is produced from a mixture of cyclohexanol and cyclohexanone called "KA oil", the abbreviation of "ketone-alcohol oil." The KA oil is oxidized with nitric acid to give adipic acid, via a multistep pathway. Early in the reaction the cyclohexanol is converted to the ketone, releasing nitrous acid:
HOC₆H₁₁ + HNO₃ → OC₆H₁₀ + HNO₂ + H₂O
Among its many reactions, the cyclohexanone is nitrosated, setting the stage for the scission of the C- C bond:
HNO₂ + HNO₃ → NO+NO₃^- + H₂O
OC₆H₁₀ + NO⁺→ OC₆H₉^-2 - NO + H⁺
Side products of the method include glutaric and succinic acids.
Related processes start from cyclohexanol, which is obtained from the hydrogenation of phenol.

Методы производства

Adipic acid is prepared by nitric acid oxidation of cyclohexanol or cyclohexanone or a mixture of the two compounds. Recently, oxidation of cyclohexene with 30% aqueous hydrogen peroxide under organic solvent- and halide-free conditions has been proposed as an environmentally friendly alternative for obtaining colorless crystalline adipic acid.

Реакции

Adipic acid is a dibasic acid (can be deprotonated twice). Its pKa's are 4.41 and 5.41.
With the carboxylate groups separated by four methylene groups, adipic acid is suited for intramolecular condensation reactions. Upon treatment with barium hydroxide at elevated temperatures, it undergoes ketonization to give cyclopentanone.

Общее описание

Adipic acid is a white crystalline solid. Adipic acid is insoluble in water. The primary hazard is the threat to the environment. Immediate steps should be taken to limit its spread to the environment. Adipic acid is used to make plastics and foams and for other uses.

Реакции воздуха и воды

Dust may form explosive mixture with air [USCG, 1999]. Insoluble in water.

Угроза здоровью

Exposures to adipic acid cause pain, redness of the skin and eyes, tearing or lacrimation. Adipic acid has been reported as a non-toxic chemical. Excessive concentrations of adipic acid dust are known to cause moderate eye irritation, irritation to the skin, and dermatitis.It may be harmful if swallowed or inhaled. It causes respiratory tract irritation with symptoms of coughing, sneezing, and blood-tinged mucous.

Фармацевтические приложения

Adipic acid is used as an acidifying and buffering agent in intramuscular, intravenous and vaginal formulations. It is also used in food products as a leavening, pH-controlling, or flavoring agent.
Adipic acid has been incorporated into controlled-release formulation matrix tablets to obtain pH-independent release for both weakly basicand weakly acidic drugs.It has also been incorporated into the polymeric coating of hydrophilic monolithic systems to modulate the intragel pH, resulting in zero-order release of a hydrophilic drug.The disintegration at intestinal pH of the enteric polymer shellac has been reported to improve when adipic acid was used as a pore-forming agent without affecting release in the acidic media.Other controlled-release formulations have included adipic acid with the intention of obtaining a late-burst release profile.

Профиль безопасности

Poison by intraperitoneal route. Moderately toxic by other routes. A severe eye irritant. Combustible when exposed to heat or flame; can react with oxidzing materials. When heated to decomposition it emits acrid smoke and fumes.

Безопасность

Adipic acid is used in pharmaceutical formulations and food products. The pure form of adipic acid is toxic by the IP route, and moderately toxic by other routes. It is a severe eye irritant, and may cause occupational asthma.
LD₅₀ (mouse, IP): 0.28 g/kg
LD₅₀ (mouse, IV): 0.68 g/kg
LD₅₀ (mouse, oral): 1.9 g/kg
LD₅₀ (rat, IP): 0.28 g/kg
LD₅₀ (rat, oral): >11 g/kg

Возможный контакт

Workers in manufacture of nylon, plasticizers, urethanes, adhesives, and food additives

Описание

Адипиновая кислота представляет собой бесцветные моноклинные кристаллы легко растворяющиеся в спирте или эфире и трудно в воде. Адипиновая кислота - одна из представителей карбоновых кислот. Синоним этого вещества: гександиовая кислота. Она представляет собою маленькие бесцветные кристаллы, кислые на вкус. В природе это вещество в небольшом количестве содержится в красной свёкле.

Применение

Адипиновая кислота важнейший полупродукт в производстве синтетических волокон нейлона, полигексаметиленадипинамида, ее эфиров, полиуретанов. Также адипиновая кислота применяется в виде пищевой добавки E355, а именно: в производстве сухих ароматизированных десертов, в желеобразных десертах, в начинках и отделочных полуфабрикатах для выпечки, в сухих смесях для приготовления напитков. Эфиры адипиновой кислоты применяются как пластификаторы и смазочные масла.

хранилище

Adipic acid is normally stable but decomposes above boiling point. It should be stored in a tightly closed container in a cool, dry place, and should be kept away from heat, sparks, and open flame.

Безопасность

Адипиновая кислота (гексан-1,6-диовая кислота; 1,4-бутандикарбоновая кислота; 1,6-гександиовая кислота; гександиовая кислота) по параметрам острой токсичности при внутрижелудочном и ингаляционном поступлении отнесен к умеренно опасным веществам (3 класс опасности); при накожном нанесении отнесен к малоопасным веществам (4 класс опасности). Продукт обладает слабыми кумулятивными свойствами; раздражающим действием на кожу, слизистые оболочки глаз и верхних дыхательных путей; существует риск серьезного раздражения глаз; проникает через неповрежденные кожные покровы. Не вызывает сенсибилизирующего действия при контакте с кожными покровами в исследованиях на животных. Не оказывает влияния на репродуктивную функцию, не обладает тератогенным и канцерогенным действием в экспериментах на животных, мутагенным действием в экспресс-тестах на бактериях и исследованиях в условиях "in vitro".

Производство

В трехгорлой колбе, снабженной мешалкой и термометром, растворяют 2 г карбоната натрия в 10 мл воды. К полученному раствору прибавляют 1 г циклогексена, а затем небольшими порциями при энергичном перемешивании вносят через боковой тубус растертый в тонкий порошок перманганат калия. В процессе добавления окислителя температура не должна быть выше 30 С, поэтому колбу периодически охлаждают в водяной бане. После окончания реакции и исчезновения малинового окрашивания выпавший осадок диоксида марганца отфильтровывают, к фильтрату прибавляют 4,7 мл 50%-ной серной кислоты до кислой реакции (pH 1).
Выпавшую адипиновую кислоту отфильтровывают, промывают небольшим количеством ледяной воды и перекристаллизовывают из воды или 50% спирта. Т.пл. 151 С.
Выход 1,2 г (68%).
Без изменения методики загрузку можно увеличить в 10-20 раз. Аналогичным образом адипиновая кислота может быть получена из циклогексанола или циклогексанона.

Перевозки

UN3077 Environmentally hazardous substances, solid, n.o.s., Hazard class: 9; Labels: 9-Miscellaneous hazardous material, Technical Name Required

Методы очистки

For use as a volumetric standard, adipic acid is crystallised once from hot water with the addition of a little animal charcoal, dried at 120o for 2hours, then recrystallised from acetone and again dried at 120o for 2hours. Other purification procedures include crystallisation from ethyl acetate and from acetone/petroleum ether, fusion followed by filtration and crystallisation from the melt, and preliminary distillation under vacuum. [Beilstein 2 IV 1956.]

Несовместимости

Adipic acid is incompatible with strong oxidizing agents as well as strong bases and reducing agents. Contact with alcohols, glycols, aldehydes, epoxides, or other polymerizing compounds can result in violent reactions.

Утилизация отходов

Dissolve or mix the material with a combustible solvent and burn in a chemical incinerator equipped with an afterburner and scrubber. All federal, state, and local environmental regulations must be observed

Меры предосторожности

Occupational workers should avoid contact of the adipic acid with the eyes, avoid breathing dust, and keep the container closed. Workers should use adipic acid only with adequate ventilation. Workers should wash thoroughly after handling adipic acid and keep away from heat, sparks, and flame. Also, workers should use rubber gloves and laboratory coats, aprons, or coveralls, and avoid creating a dust cloud when handling, transferring, and cleaning up.

Регуляторный статус

GRAS listed. Included in the FDA Inactive Ingredients Database (IM, IV, and vaginal preparations). Accepted for use as a food additive in Europe. Included in an oral pastille formulation available in the UK. Included in the Canadian List of Acceptable Non-medicinal Ingredients.