Валериановая кислота

Описание

Valeric acid, or pentanoic acid, is a straight - chain alkyl carboxylic acid with the chemical formula C₅H₁₀O₂. Like other lowmolecular- weight carboxylic acids, it has a very unpleasant odor. It is found naturally in the perennial flowering plant valerian (Valeriana officinalis), from which it gets its name. Its primary use is in the synthesis of its esters. Volatile esters of valeric acid tend to have pleasant odors and are used in perfumes and cosmetics. Ethyl valerate and pentyl valerate are used as food additives because of their fruity flavors.
Valeric acid appears similar in structure to GHB and the neurotransmitter GABA in that it is a short-chain carboxylic acid, although it lacks the alcohol and amine functional groups that contribute to the biological activities of GHB and GABA, respectively. It differs from valproic acid simply by lacking a 3- carbon side - chain.

Химические свойства

Valeric acid has an unpleasant odor and flavor, similar to butyric acid. May consist of one or a mixture of isomers of n-pentanoic acid and/or 2- or 3-methyl-butanoic acid.

Вхождение

The acid is not too common in nature; reported (as the corresponding ester) found in the essential oil of Boronia anemonifolia, in pineapple fruits and in other plants; also identified as acid or the corresponding ester in the essential oil of lemon petitgrain. Also reported found in apple, apple juice, banana, orange juice, bilberry, cranberry, strawberry, raspberry, papaya, grapes, celery, onion, baked potato, tomato, corn mint oil, breads, cheeses, milk, yogurt, butter, cheddar cheese, lean and fatty fish, fish oil, cooked meats, hop oil, beer, rum, whiskies, grape wines, cocoa, tea, roasted filberts, peanuts and pecans, honey, soybeans, coconut meat and milk, cloudberry, passion fruit, starfruit, trassi, mango, jackfruit, licorice, calamus, sake, buckwheat, watercress, laurel, peated malt, wort, kiwifruit, loquat, Bourbon vanilla, shrimps, oyster, scallop, cape gooseberry, sea buckthorn, Chinese quince and maté.

Использование

valeric acid is obtained from valerian extract, which is considered skin conditioning.

Подготовка

By oxidation of n-amyl alcohol or, together with other isomers, by distillation of valerian roots; also by reacting butyl bromide and sodium cyanide with subsequent saponification of the formed butyl nitrile.

Определение

ChEBI: A straight-chain saturated fatty acid containing five carbon atoms.

Общее описание

A colorless liquid with a penetrating unpleasant odor. Density 0.94 g / cm3. Freezing point -93.2°F (-34°C). Boiling point 365.7°F (185.4°C). Flash point 192°F (88.9°F). Corrosive to metals and tissue.

Реакции воздуха и воды

Water soluble.

Профиль реактивности

Valeric acid is a carboxylic acid. Exothermically neutralizes bases, both organic and inorganic, producing water and a salt. Can react with active metals to form gaseous hydrogen and a metal salt. Reacts with cyanide salts to generate gaseous hydrogen cyanide. Flammable and/or toxic gases and heat are generated by reaction with diazo compounds, dithiocarbamates, isocyanates, mercaptans, nitrides, and sulfides. Reacts with sulfites, nitrites, thiosulfates and dithionites to generate flammable and/or toxic gases and heat. Reacts with carbonates and bicarbonates to generate a harmless gas (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. May catalyze (increase the rate of) chemical reactions.

Угроза здоровью

Corrosive. Very destructive to tissues of the mucous membranes, upper respiratory tract, eyes, and skin. Symptoms may include burning sensation, coughing, wheezing, laryngitis, shortness of breath, nausea and vomiting. Extremely destructive to skin. May be absorbed through the skin.

Пожароопасность

Special Hazards of Combustion Products: Irritating vapors and toxic gases, such as carbon dioxide and carbon monoxide, may be formed when involved in fire.

Профиль безопасности

Moderately toxic by ingestion, intravenous, and subcutaneous routes. Mildly toxic by inhalation. A corrosive irritant to skin, eyes, and mucous membranes. Combustible liquid. When heated to decomposition it emits acrid smoke and irritating fumes. Used in perfumes.

Методы очистки

Water is removed from the acid by distillation using a Vigreux column (p 11), until the boiling point reaches 183o. A few crystals of KMnO4 are added, and after refluxing, the distillation is continued. [Andrews & Keefer J Am Chem Soc 83 3708 1961, Beilstein 2 H 299, 2 I 130, 2 II 263, 2 III 663, 2 IV 868.]