Uses of Carboxylic Acids

Acetic acid is, by a wide margin, the most familiar and most widely used carboxylic acid, valued in two quite different contexts. In everyday and food use, dilute aqueous acetic acid (typically $5$-$8\%$ by volume) is sold and consumed as vinegar, one of the oldest known food preservatives and flavourings, its mild acidity both imparting a characteristic sharp taste and inhibiting the growth of many spoilage microorganisms. Industrially, concentrated acetic acid is the essential starting material for cellulose acetate, made by reacting cellulose (from wood pulp or cotton) with acetic anhydride (itself derived from acetic acid); cellulose acetate is spun into acetate fibre for textiles and is also cast into photographic and cinematographic film base. Acetic acid is likewise the raw material for polyvinyl acetate, an important polymer used in adhesives, paints and chewing-gum base, made by polymerising vinyl acetate (itself derived from acetic acid and ethylene).

Formic acid, the simplest carboxylic acid, is put to rather different, more specialised industrial uses. It is widely used in the leather-tanning industry, where its acidity helps prepare and treat hides before tanning, and in textile dyeing and finishing, where it is used to adjust pH and assist the uptake of certain dyes onto fabric. Formic acid is also used as a coagulant for rubber latex, helping to precipitate the rubber particles suspended in natural latex sap so that they can be collected and processed into solid rubber, and, on a smaller scale, as an antibacterial and preservative agent in livestock feed. …