General Description
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.
Reactivity Profile
PENTANOIC ACID(109-52-4) 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.
Air & Water Reactions
Water soluble.
Health Hazard
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.
Fire Hazard
Special Hazards of Combustion Products: Irritating vapors and toxic gases, such as carbon dioxide and carbon monoxide, may be formed when involved in fire.
Chemical Properties
Colorless liquid; penetrating odor and
taste. Soluble in water,
alcohol and ether. Undergoes reactions typical of
normal monobasic organic acids. Combustible.
Chemical Properties
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.
Occurrence
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.
Definition
ChEBI: A straight-chain saturated fatty acid containing five carbon atoms.
Preparation
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.
Aroma threshold values
Detection: 940 ppb to 3 ppm
Taste threshold values
Taste characteristics at 100 ppm: acidic, dairy-like with milky and cheese nuances.
Flammability and Explosibility
Nonflammable
Purification Methods
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.]
