Products
Formic acid is available in pharmacies and drugstores in various dilutions. It is also included as an active ingredient in some medicines and in medical products, for example, in liniments and in wart remedies.
Structure and properties
Formic acid (HCOOH, Mr = 102.1 g/mol) is the simplest carboxylic acid. It consists of a hydrogen atom bonded to a carboxy group. It exists as a colorless to yellow liquid with a pungent odor and is miscible in water. Formic acid is a natural substance found, for example, in stinging nettles and ants, which use the acid for defense. In the past, it was also obtained from ants by distillation. The technical term Acidum formicum is derived from the Latin name (ant). Its salts and esters are called formates. With a pKa of 3.77, formic acid is a stronger acid than acetic acid. Different concentrations are distinguished (selection):
- Dilute formic acid: 25%.
- Technical formic acid: e.g. 85%.
- Anhydrous formic acid: ≥ 98%
Effects
Formic acid has circulatory, irritant, corrosive, antimicrobial and acidic properties.
Indications for use
In the form of suitable preparations and dilutions (examples):
- Externally for muscle and joint pain.
- As a preservative.
- In beekeeping for the treatment of infestation with varroa mites in honey bees.
- As a cleaning agent, for descaling.
- For the external treatment of warts.
- As a reagent, for chemical syntheses.
Adverse effects
Formic acid has irritant to corrosive properties depending on the concentration of the solution and may cause burns to the skin, mucous membranes and eyes. The corresponding precautionary measures in the safety data sheet must be observed. If formic acid is heated or brought into contact with an acid, it may decompose to form toxic carbon monoxide (CO) and water.
