Formic acid
[CAS# 64-18-6]

Identification

• Classification: Organic raw materials >> Carboxylic compounds and derivatives >> Acyclic carboxylic acid
• Name: Formic acid
• Synonyms: Methanoic acid
• Molecular Formula: CH₂O₂
• Molecular Weight: 46.02
• CAS Registry Number: 64-18-6 (920-42-3)
• EC Number: 200-579-1
• SMILES: C(=O)O

Properties

• Density: 1.2±0.1 g/cm³ Calc.^*, 1.22 g/mL (Expl.)
• Melting point: 7 - 9 °C (Expl.)
• Boiling point: 100.6±9.0 °C 760 mmHg (Calc.)^*, 100 - 101 °C (Expl.)
• Flash point: 29.9±13.4 °C (Calc.)^*, 50 °C (Expl.)
• Solubility: Miscible (Expl.)
• Index of refraction: 1.342 (Calc.)^*, 1.371 (Expl.)

^* Calculated using Advanced Chemistry Development (ACD/Labs) Software.

Safety Data

• Hazard Symbols: GHS02;GHS05;GHS06;GHS07 Danger
• Risk Statements: H226-H302-H314-H318-H331
• Safety Statements: P210-P233-P240-P241-P242-P243-P260-P261-P264-P264+P265-P270-P271-P280-P301+P317-P301+P330+P331-P302+P361+P354-P303+P361+P353-P304+P340-P305+P354+P338-P316-P317-P321-P330-P363-P370+P378-P403+P233-P403+P235-P405-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Skin corrosion	Skin Corr.	1A	H314
Flammable liquids	Flam. Liq.	3	H226
Acute toxicity	Acute Tox.	4	H302
Acute toxicity	Acute Tox.	3	H331
Serious eye damage	Eye Dam.	1	H318
Specific target organ toxicity - single exposure	STOT SE	1	H370
Skin corrosion	Skin Corr.	1B	H314
Skin corrosion	Skin Corr.	1	H314
Acute toxicity	Acute Tox.	4	H332
Substances or mixtures corrosive to metals	Met. Corr.	1	H290
Chronic hazardous to the aquatic environment	Aquatic Chronic	3	H412
Skin irritation	Skin Irrit.	2	H315
Eye irritation	Eye Irrit.	2	H319
Specific target organ toxicity - single exposure	STOT SE	3	H335
Skin corrosion	Skin Corr.	1C	H314
Reproductive toxicity	Repr.	2	H361
Specific target organ toxicity - repeated exposure	STOT RE	1	H372

• Transport Information: UN 1779

Discovery and Applications

Formic acid is the simplest carboxylic acid with the chemical formula HCOOH. It was first isolated in the 17th century from the distillation of ants, which inspired its name derived from the Latin word "formica," meaning ant. The pure compound was later synthesized and characterized in the 18th century, establishing its chemical structure and properties.

Formic acid is a colorless, pungent liquid that is miscible with water and many organic solvents. It is naturally present in the venom of certain ants and stinging insects and is found in small amounts in various plants and fruits. Industrially, formic acid is produced primarily by the hydrolysis of methyl formate or through carbonylation processes.

The compound has a wide range of applications across industries due to its acidic and reducing properties. In agriculture, formic acid is used as a preservative and antibacterial agent in livestock feed to prevent microbial growth and spoilage. It also functions as a silage additive to improve fermentation and preservation of forage.

In the textile industry, formic acid is employed in dyeing and finishing processes, where it acts as a pH regulator and helps fix dyes to fabrics. It is also used in leather processing for tanning and as a coagulating agent.

Formic acid serves as a key intermediate in chemical synthesis. It is used to produce formate esters, formamide, and other formyl-containing compounds. Its reducing properties enable applications in metal processing, such as pickling and cleaning of metals, where it removes oxides and rust without aggressive corrosion.

The compound’s role as a green and biodegradable acid makes it attractive in environmentally conscious processes. It is used in deicing agents for roads and aircraft, offering an alternative to more corrosive chemicals.

Formic acid also finds application in pharmaceuticals and cosmetics as a pH adjuster and antimicrobial agent. Its ability to inhibit microbial growth helps extend product shelf life and maintain quality.

From a safety perspective, formic acid is corrosive and can cause irritation to skin, eyes, and respiratory tract. Concentrated solutions require careful handling and appropriate protective measures. Despite this, it is considered less hazardous than many other industrial acids when used properly.

In summary, formic acid is a naturally occurring and industrially produced simple carboxylic acid discovered through its isolation from ants. It plays a vital role in agriculture, textiles, chemical synthesis, metal treatment, and environmental applications. Its chemical properties and biodegradability contribute to its continued widespread use, while safety practices ensure its responsible handling.

References

2022. Metal-Free Hydroxymethylation of Indole Derivatives with Formic Acid as an Alternative Way to Indirect Utilization of CO2. The Journal of Organic Chemistry, 87(3).
DOI: 10.1021/acs.joc.1c02831

2022. Toward a glycyl radical enzyme containing synthetic bacterial microcompartment to produce pyruvate from formate and acetate. Proceedings of the National Academy of Sciences of the United States of America, 119(8).
DOI: 10.1073/pnas.2116871119

2022. Fabrication of a biocathode for formic acid production upon the immobilization of formate dehydrogenase from Candida boidinii on a nanoporous carbon. Chemosphere, 291(Pt 2).
DOI: 10.1016/j.chemosphere.2021.133117