Citric acid monohydrate
[CAS# 5949-29-1]

Identification

• Classification: API >> Digestive system medication >> Digestive drug
• Name: Citric acid monohydrate
• Molecular Formula: C₆H₈O₇.H₂O
• Molecular Weight: 210.14
• CAS Registry Number: 5949-29-1
• EC Number: 611-842-9
• SMILES: C(C(=O)O)C(CC(=O)O)(C(=O)O)O.O

Properties

• Density: 1.54
• Melting point: 135-152 °C
• Flash point: 173.9 °C
• Water solubility: 1630 g/L (20 °C)

Safety Data

• Hazard Symbols: GHS07 Warning
• Risk Statements: H315-H319-H335
• Safety Statements: P261-P264-P264+P265-P271-P280-P302+P352-P304+P340-P305+P351+P338-P319-P321-P332+P317-P337+P317-P362+P364-P403+P233-P405-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Eye irritation	Eye Irrit.	2	H319
Specific target organ toxicity - single exposure	STOT SE	3	H335
Skin irritation	Skin Irrit.	2	H315
Serious eye damage	Eye Dam.	1	H318
Acute toxicity	Acute Tox.	5	H303
Eye irritation	Eye Irrit.	2A	H319
Acute toxicity	Acute Tox.	5	H313
Flammable liquids	Flam. Liq.	2	H225

Discovery and Applications

Citric acid was first isolated from lemon juice in 1784 by Swedish chemist Carl Wilhelm Scheele. However, it was not until the early 20th century that citric acid monohydrate, a hydrated form of citric acid, was produced on an industrial scale through fermentation with Aspergillus niger. This method, pioneered by James Currie, revolutionized the production of citric acid, making it more accessible and suitable for industrial use. Citric acid monohydrate, with the molecular formula C6H8O7�H2O, is a white crystalline powder. It is highly soluble in water and ethanol, which helps it function in a variety of applications. The presence of water molecules in the crystal structure enhances its stability and handling ability in different processes.

One of the main uses of citric acid monohydrate is as a flavoring and preservative in the food and beverage industry. Its pungent taste enhances the flavor of soft drinks, confectionery, and canned foods. In addition, its ability to regulate acidity is useful in maintaining the freshness and shelf life of various foods. Its use as a natural preservative is in line with consumer preferences for healthier ingredients in food.

In medicine, citric acid monohydrate acts as an excipient, providing stability and enhancing the solubility of active ingredients in drugs. It is used in effervescent tablets and oral solutions, where its acidic properties help promote drug release and absorption. Its chelating action also helps stabilize and maintain the efficacy of drug formulations.

In addition to food and pharmaceuticals, citric acid monohydrate has a variety of industrial functions. Due to its ability to break down scale and remove stains, it is used in cleaning products, making it a popular choice for environmentally friendly cleaners. In cosmetics, it can adjust pH and act as a preservative, thereby improving the stability and safety of skin care products.

The biodegradability and non-toxic properties of citric acid monohydrate make it environmentally friendly. Its use in cleaning products reduces reliance on harsh chemicals and promotes environmentally friendly practices. In addition, its use as a soil conditioner in agriculture helps improve soil health and nutrient availability, supporting sustainable agriculture.

Ongoing research explores innovative uses for citric acid monohydrate in areas such as biodegradable plastics, water treatment, and bio-based chemicals. Advances in biotechnology and green chemistry are expected to expand its application and contribute to a more sustainable and circular economy.

References

2024. Various Properties of Green Synthesized Carbon Quantum Dots. Green Carbon Quantum Dots.
DOI: 10.1007/978-981-97-6203-3_3

1991. Periodontal Healing Following Guided Tissue Regeneration With Citric Acid and Fibronectin Application. Journal of Periodontology, 62(1).
DOI: 10.1902/jop.1991.62.1.21

1987. Effect of Citric Acid and Various Concentrations of Fibronectin on Healing Following Periodontal Flap Surgery in Dogs. Journal of Periodontology, 58(10).
DOI: 10.1902/jop.1987.58.10.667