Triethyl citrate
[CAS# 77-93-0]

Identification

• Classification: API >> Respiratory medication >> Antitussive
• Name: Triethyl citrate
• Molecular Formula: C₁₂H₂₀O₇
• Molecular Weight: 276.28
• CAS Registry Number: 77-93-0
• EC Number: 201-070-7
• SMILES: CCOC(=O)CC(CC(=O)OCC)(C(=O)OCC)O

Properties

• Density: 1.136 g/mL
• Melting point: -46 ºC
• Boiling point: 294 ºC
• Refractive index: 1.44-1.443
• Flash point: 151 ºC
• Water solubility: 5.7 g/100 mL (25 ºC)

Safety Data

• Hazard Symbols: GHS07 Warning
• Hazard Statements: H302-H315-H319-H335
• Precautionary Statements: P261-P301+P312-P302+P352-P304+P340-P305+P351+P338

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Acute toxicity	Acute Tox.	4	H332
Carcinogenicity	Carc.	1B	H350
Flammable gases	Flam. Gas	1	H220
Germ cell mutagenicity	Muta.	1B	H340
Eye irritation	Eye Irrit.	2	H319
Skin irritation	Skin Irrit.	2	H315

Discovory and Applicatios

Triethyl citrate is a colorless, odorless, and biodegradable ester formed by the reaction of citric acid with ethanol. It is chemically classified as a citrate ester, specifically the triethyl ester of citric acid. Triethyl citrate was first synthesized and characterized during the early 20th century as part of the broader exploration of citric acid derivatives and their potential applications.

Its primary characteristic is being a non-toxic, biodegradable plasticizer and solvent with a low volatility and good compatibility with various polymers. Triethyl citrate has a relatively high boiling point and excellent miscibility with many organic solvents, making it suitable for diverse industrial and pharmaceutical uses.

In the pharmaceutical industry, triethyl citrate is widely used as a plasticizer in the formulation of controlled-release drug delivery systems. By incorporating triethyl citrate into polymeric coatings or matrices, drug release profiles can be modified to achieve sustained or delayed release. Its plasticizing effect improves the flexibility and mechanical properties of polymer films, facilitating the manufacturing of tablets and capsules with desired dissolution characteristics.

Triethyl citrate is also employed in the production of biodegradable plastics and polymer films due to its compatibility with materials such as cellulose acetate and polyvinyl chloride (PVC). As a plasticizer, it imparts softness and flexibility to otherwise brittle polymers, expanding their application range in packaging, medical devices, and environmentally friendly materials.

In the food industry, triethyl citrate is recognized as a safe additive and is utilized as a solvent for flavorings and as a stabilizer for emulsions. Its low toxicity and biodegradability have contributed to its acceptance as a food-grade ingredient under various regulatory standards.

Furthermore, triethyl citrate finds application in cosmetics and personal care products. It acts as a solvent, plasticizer, and emollient in formulations such as nail polishes, hair sprays, and lotions. Its ability to improve film formation and enhance product texture makes it valuable in these applications.

Triethyl citrate is generally produced by the esterification of citric acid with ethanol under acidic conditions, followed by purification steps to achieve high purity. Its biodegradability and low toxicity profile have made it a preferred alternative to phthalate plasticizers, which have faced regulatory restrictions due to health concerns.

In summary, triethyl citrate is a triester of citric acid first developed in the early 20th century and recognized for its plasticizing and solvent properties. It is widely used in pharmaceutical formulations to modify drug release, in biodegradable plastics, food products, and personal care items. Its safety, biodegradability, and effectiveness continue to support its broad industrial and commercial applications.

References

1959. Toxicology of the citric acid esters: Tributyl citrate, acetyl tributyl citrate, triethyl citrate, and acetyl triethyl citrate. Toxicology and Applied Pharmacology, 1(3).
DOI: 10.1016/0041-008x(59)90113-9

2024. New Tricarboxylate Plasticizers for Use in Polylactic Acid: Synthesis, Thermal Behavior, Mechanical Properties and Durability. Journal of Polymers and the Environment, 32(10).
DOI: 10.1007/s10924-024-03254-0

2024. Antiplasticizing effect of triethyl citrate on an isosorbide-based polycarbonate. Journal of Polymer Research, 31(7).
DOI: 10.1007/s10965-024-04059-4