Acetic Acid Properties and Formula
Acetic acid also called ethanoic acid having the molecular formula CH3COOH prepared industrially by various methods and uses commonly as a solvent and in the preparation of organic chemicals like acetate, acetone, acetic anhydride, acetaldehyde alcohol, vinegar, etc. Glacial acetic acid is a pungent corrosive liquid solution with the molar mass 60 gm mol-1 miscible in all proportions with water, ethanol, and ether. The solubility due to the formation of hydrogen bonding with the water molecule. Acetic acid stable towards oxidizing agents and a useful solvent for the chromium trioxide oxidation process.
When acetylene passes over worm acetic acid in the presence of mercuric ions uses as a chemical catalyst formed vinyl acetate and ethylidene diacetate. Vinyl acetate used in the plastic industry for the production of plastics toys and daily used equipment. Acetic acid ionizes or donates its proton to water to form the conjugate base like acetate ion with two equivalent resonating structures. Therefore the internal energy of the anion is lower than the unionized acid. But in the case of alcohol, there is no resonance hybrid form in alkoxide ion. The standard free energy for the ionization of monocarboxylic acid will be more negative than that of the alcohol.
Preparation of Acetic acid
One of the earliest methods for preparing glacial acetic acid by destructive distillation of wood to found pyroligneous acid. This contains ten percent of acid solution treated by neutralizing with lime and distilling as the volatile compounds. This volatile compound is a mixture of methanol and acetone. On the distillation of methanol and acetone with sulfuric acid gives dilute CH3COOH. But industrially acetic CH3COOH was prepared by several methods.
The air oxidation of acetaldehyde in the presence of manganous ion. The air oxidation of liquid hydrocarbon like n-butane passes under pressure at 130-230 ºC temperature in the presence of a suitable catalyst like manganous ion. The reaction between carbon monoxide and methanol under pressure in the presence of cobalt octacarbonyl at about 210 °C.
Acetic Acid in Vinegar
Vinegar is the 6-10 percent of the aqueous solution of acetic acid that uses for the preservation of food made in several ways. Melt vinegar in organic chemistry prepared by the oxidation of wort or ethyl alcohol by means of bacteria Mycoderma aceti.
CH3CH2OH + O2 → CH3COOH + H2O
In the quick vinegar process, a barrel containing a specific amount of strong vinegar and 10 percent aqueous solution of ethanol, phosphates, and inorganic salts for the fermentation process for the production of acetic acid solution. A plentiful supply of air or oxygen necessary otherwise the oxidation is incomplete and acetaldehyde is produced.
General Chemical Reactions
The acids react with strong electropositive metals like lithium or sodium with the liberation of hydrogen (2CH3COOH + 2Na → 2CH3COONa + H2). The monocarboxylic acids like CH3COOH chemical bonding with alcohol to form the ester (CH3COOH + CH3OH → CH3CO2CH3 + H2O). Phosphorus trichloride, pentachloride, or thionol chloride act upon monocarboxylic acid to form acid chloride (3CH3CO2H + PCl3 → 3CH3COCl + H3PO3).
CH3COOH is extremely resistant to oxidation but heating with the specific heat with suitable oxidizing agents ultimately produces carbon dioxide and water. The reduction product of monocarboxylic acid depends on the nature of reducing agents uses in the chemical equilibrium reaction. Alkane or paraffin is produced when acetic acid or formic acid heating with hydrogen iodide and red phosphorus under pressure or with hydrogen under pressure at elevated temperature in the presence of a chemical catalyst like nickel.