Малеиновый ангидрид

Описание

Maleic Anhydride (MAN) is an organic compound with the chemical formula C4H203. It is the acid anhydride of maleic acid and in its pure state it is a colourless or white solid with an acrid odour. Maleic anhydride is truly a remarkable molecule in that it possesses two types of chemical functionality making it uniquely useful in chemical synthesis and applications.

Maleic Anhydride is a multifunctional chemical intermediate with applications in several fields of chemical industry. Its major end use is as feedstock in the production of unsaturated polyester resins (UPR).
These resins are used both in glass-reinforced and in unreinforced applications. The UPR end uses includes a wide range of applications in construction, marine and automobile industries.

Химические свойства

Maleic anhydride is colorless needles, white lumps, or pellets. Irritating, choking odor. Dissolves in water to produce maleic acid. Dissolves in ethanol and produces esters.

Физические свойства

White, hydroscopic crystals (usually shipped as briquettes). Odor threshold concentration is 0.32 ppm (quoted, Amoore and Hautala, 1983).

Использование

Maleic Anhydride is heterocyclic compound used in the manufacture of unsaturated polyester resins. It has a wide range of other applications; it is used in synthetic tensides, insecticides, herbicides and fungicides.

Подготовка

To a flask equipped with a Dean-Stark trap, condenser, and mechanical stirrer is added 116 gm (1.0 mole) of maleic acid and 120 ml of tetrachloroethane. The contents are heated, the water (18 ml, 1.0 mole) distilled off as the azeotrope, and the residue distilled under reduced pressure to afford 87.7 gm (89.5%) of the anhydride, b.p. 82-84°C (15 mm), m.p. 53°C. The residue remaining in the flask consists of about 10 gm of fumaric acid, m.p. 287°C.
Fumaric and maleic acids both give maleic anhydride on heating. Fumaric acid must first be heated to a higher temperature to effect its conversion to maleic acid prior to its dehydration.

Методы производства

Maleic anhydride was traditionally manufactured by the oxidation of benzene or other aromatic compounds. As of 2006, only a few smaller plants continue to use benzene; due to rising benzene prices, most maleic anhydride plants now use n-butane as a feedstock.
In both cases, benzene and butane are fed into a stream of hot air, and the mixture is passed through a catalyst bed at high temperature. The ratio of air to hydrocarbon is controlled to prevent the mixture from catching on fire. Vanadium pentoxide and molybdenum trioxide are the catalysts used for the benzene route, whereas vanadium and phosphorus oxides are used for the butane route.
2 CH₃CH₂CH₂CH₃ + 7 O₂ → 2 C₂H₂(CO)₂O + 8 H₂O.

Определение

ChEBI: Maleic anhydride is a cyclic dicarboxylic anhydride that is the cyclic anhydride of maleic acid. It has a role as an allergen. It is a cyclic dicarboxylic anhydride and a member of furans.

Реакции

The chemistry of maleic anhydride is very rich, reflecting its ready availability and bifunctional reactivity. It hydrolyzes, producing maleic acid, cis-HOOC–CH=CH–COOH. With alcohols, the halfester is generated, e.g., cis-HOOC–CH=CH–COOCH₃.
Maleic anhydride is a potent dienophile in Diels-Alder reactions. It is also a ligand for low-valent metal complexes, examples being Pt(PPh₃)₂(MA) and Fe(CO)₄(MA).
Maleic anhydride dimerizes in a photochemical reaction to form cyclo butane tetra carboxylic dianhydride (CBTA). This compound is used in the production of polyimides and as an alignment film for liquid crystal displays.

Общее описание

Colorless crystalline needles, flakes, pellets, rods, briquettes, lumps or a fused mass. Melts at 113°F. Shipped both as a solid and in the molten state. Vapors, fumes and dusts strong irritate the eyes, skin and mucous membranes. Flash point 218°F. Autoignition temperature 890°F. Used to make paints and plastics and other chemicals.

Реакции воздуха и воды

Soluble in water. Reacts slowly with water to form maleic acid and heat.

Профиль реактивности

Maleic anhydride react vigorously on contact with oxidizing materials. Reacts exothermically with water or steam. Undergoes violent exothermic decomposition reactions, producing carbon dioxide, in the presence of strong bases (sodium hydroxide, potassium hydroxide, calcium hydroxide), alkali metals (lithium, sodium, potassium), aliphatic amines (dimethylamine, trimethylamine), aromatic amines (pyridine, quinoline) at temperatures above 150° C [Vogler, C. A. et al., J. Chem. Eng. Data, 1963, 8, p. 620]. A 0.1% solution of pyridine (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]. Maleic anhydride is known as an excellent dienophile in the Diels-Alder reaction to produce phthalate ester derivatives. These reactions can be extremely violent, as in the case of 1-methylsilacyclopentadiene [J. Organomet., Chem., 1979, 179, c19]. Maleic anhydride undergoes a potentially explosive exothermic Diels-Alder reaction with 1-methylsilacyclopenta-2,4-diene at 150C [Barton, T. J., J. Organomet. Chem., 1979, 179, C19], and is considered an excellent dieneophile for Diels-alder reactions [Felthouse, Timothy R. et al. "Maleic anhydride , Maleic Acid, and Fumaric Acid." Kirk-Othmer Encyclopedia of Chemical Technology. John Wiley & Sons, Inc. 2005].

Опасность

Irritant to tissue. Dermal and respiratory sensitization. Questionable carcinogen.

Угроза здоровью

Inhalation causes coughing, sneezing, throat irritation. Skin contact causes irritation and redness. Vapors cause severe eye irritation; photophobia and double vision may occur.

Пожароопасность

Behavior in Fire: When heated above 300°F in the presence of various materials may generate heat and carbon dioxide. Will explode if confined.

Профиль безопасности

Poison by ingestion and intraperitoneal routes. Moderately toxic by skin contact. A corrosive irritant to eyes, skin, and mucous membranes. Can cause pulmonary edema. Questionable carcinogen with experimental tumorigenic data. Mutation data reported. A pesticide. Combustible when exposed to heat or flame; can react vigorously on contact with oxidizing materials. Explosive in the form of vapor when exposed to heat or flame. Reacts with water or steam to produce heat. Violent reaction with bases (e.g., sodmm hydroxide, potassium hydroxide, calcium hydroxide), dkah metals (e.g., sodium, potassium), amines (e.g., dimethylamine, triethylamine), lithium, pyridine. To fight fire, use alcohol foam. Incompatible with cations. When heated to decomposition (above 150℃) it emits acrid smoke and irritating fumes. See also ANHYDRIDES.

Возможный контакт

Maleic anhydride is used in unsaturated polyester resins; Agricultural chemical, and lubricating additives; in the manufacture of unsaturated polyester resins; in the manufacture of fumaric acid; in alkyd resin manufacture; in the manufacture of pesticides e.g., malathion, maleic hydrazide, and captan).

Перевозки

UN2215 Maleic anhydride, Hazard class: 8; Labels: 8-Corrosive material.
Maleic Anhydride is commercialized and transported in the solid and molten forms. The molten Maleic Anhydride is transported at temperatures ranging from 60 to 80°C in well-insulated tank containers or road tankers provided with heating devices. In the solid form, it can be transported as pastilles, which are usually packed in polyethylene bags of 25 kg and transported either by rail tanker or by truck.

Методы очистки

Crystallise it from *benzene, CHCl3, CH2Cl2 or CCl4. Sublime it under reduced pressure. [Skell et al. J Am Chem Soc 108 6300 1986, Beilstein 17 III/IV 5897, 17/11 V 55.]

Несовместимости

Reacts slowly with water (hydrolyzes) to form maleic acid, a medium-strong acid. Dust may form explosive mixture with air. Reacts with strong oxidizers, oil, water, alkali metals; strong acids; strong bases. Violent reaction with alkali metals and amines above 66C. Dangerous reaction with oxidizers, amines, alkali metals, and hydroxides. Compounds of the carboxyl group react with all bases, both inorganic and organic (i.e., amines) releasing substantial heat, water and a salt that may be harmful. Incompatible with arsenic compounds (releases hydrogen cyanide gas), diazo compounds, dithiocarbamates, isocyanates, mercaptans, nitrides, and sulfides (releasing heat, toxic, and possibly flammable gases), thiosulfates and dithionites (releasing hydrogen sulfate and oxides of sulfur)

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. Controlled incineration: care must be taken that complete oxidation to nontoxic products occurs.