Acetic acid

Acetic acid is very simple compound of carboxylic acids. It is an important chemical reagent and industrial chemical that is used for producing polyethylene terephthalate which is mainly used in soft drink bottles; cellulose acetate, mainly for photographic film; and polyvinyl acetate for wood glue, as well as synthetic fibers and fabrics. In households diluted acetic acid is often used in descaling agents. In the food industry acetic acid is used under the food additive code E260 as an acidity regulator. The global demand of acetic acid is around 6.5 million tonnes per year (Mt/a), of which approximately 1.5 Mt/a is met by recycling; the remainder is manufactured from petrochemical feed-stocks or from biological sources.

Properties
Acetic acid dissolves in water in all proportions with at first a contraction and afterwards an increase in volume. It is detected by heating with ordinary alcohol and sulfuric acid, which gives rise to acetic ester or ethyl acetate, recognized by its fragrant odor; or by heating with arsenious oxide, which forms the pungent and poisonous cacodyl oxide. It is a monobasic acid, forming one normal and two acid potassium salts, and basic salts with iron, aluminium, lead and copper. Ferrous and ferric acetates are used as mordants; normal lead acetate is known in commerce as sugar of lead (q.v.); basic copper acetates are known as verdigris.

Glacial acetic acid is occasionally used as a caustic for corns. The impure acid (vinegar) may be used to bath the skin in fever; it acts like pleasant refrigerant. Vinegar which contains about 5% acetic acid, is frequently taken as a cure for obesity, but there is no warranty for this application. Its continued employment may, indeed, so injure the mucous membrane of the stomach as to interfere with digestion and so cause a morbid and dangerous reduction in weight.

The acetates constitute a valuable group of medicinal agents, the potassium salt is the most frequently employed. After absorption into the blood, the acetates are oxidized to carbonates, thus, they are remote alkalies, also are administered whenever it is desired to increase the alkalinity of the blood or to reduce the acidity of the urine, without exerting the disturbing influence of alkanes upon the digestive tract.

Occurrences
Acetic acid (acidum aceticum), CH3CO2H, is one of the most important organic acids. It occurs naturally in the juice of many plants. It is obtained in the form of a watered down solution, in which also the coloring matters of the wines and salts are dissolved; and this polluted acetic acid becomes ordinary vinegar. Ancients people used acetic acid (the from of vinegar) which was from the oxidation of alcoholic liquors. Wood-vinegar appeared in the middle ages. Towards the close of the 18th century, A. L. Lavoisier discovered that air must required to form the vinegar from alcohol. In 1830 J. B. A. Dumas transformed acetic acid into trichloracetic acid, and in 1842 L. H. F. Melsens retransformed this derivative into the original acetic acid by contraction with sodium amalgam. The analysis of trichloracetic acid from its elements was accomplished in 1843 by H. Kolbe.

Uses
"Adjuvant- Used in pesticide products to increase the effectiveness of the active ingredients, make the product easier to apply, or to allow several active ingredients to mix in one solution. Solvents, emulsifiers, and spreaders fall in this category." "Breakdown products- The chemical transformation product from metabolism of a pesticide in a biological system or from reaction of a pesticide with oxygen, water, light or other substances in the environment. In the PAN database, known breakdown products are listed as related chemicals for the parent pesticide. however, it is important to note that not all pesticide transformation products have been identified. Breakdown products can sometimes be more toxic than the starting pesticide." "Fragrance- Chemical used to add a particular odor to a pesticide product. Sometimes these fragrances are attractants for insects; other times, they are added to hide an unpleasant chemical odor." "Fumigant- Exist as gases or produce a gas when they break down in the environment. Fumigants typically kill all living things. Used in agriculture to sterilize soil before planting and to kill pests in stored food or before shipment to other countries. In urban settings, fumigants are used to treat dwellings for termites, ants, and roaches. The target pests for many soil fumigations are nematodes. Most of these pesticides are highly acutely toxic." "Insecticide- Kills insects. As used in the PAN Pesticide Database, the term 'insecticide' encompasses miticides, acaracides, and nematicides as well." "pH adjustment- An acidic or basic substance used to alter the acidity (pH) of a solution or product." "Rodenticide- Kills rodents such as rats, mice and gophers." "Soap/Surfactant- Compounds that have surfactant or detergent properties." Water treatment- Chemicals used for treating water to make it potable.