1-(2-Hydroxyethyl)-2-imidazolidinone
[CAS# 3699-54-5]

Identification

• Classification: Surfactant >> Zwitterionic surfactant >> Imidazoline type
• Name: 1-(2-Hydroxyethyl)-2-imidazolidinone
• Synonyms: 1-(2-Hydroxyethyl)imidazolidin-2-one
• Molecular Formula: C₅H₁₀N₂O₂
• Molecular Weight: 130.14
• CAS Registry Number: 3699-54-5
• EC Number: 223-032-9
• SMILES: C1CN(C(=O)N1)CCO

Properties

• Density: 1.2±0.1 g/cm³ Calc.^*
• Melting point: 46 - 51 °C (Expl.)
• Boiling point: 400.1±24.0 °C 760 mmHg (Calc.)^*, 410.6 °C (Expl.)
• Flash point: 195.8±22.9 °C (Calc.)^*, 212 °C (Expl.)
• Index of refraction: 1.503 (Calc.)^*

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

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
Specific target organ toxicity - single exposure	STOT SE	3	H335
Skin irritation	Skin Irrit.	2	H315
Eye irritation	Eye Irrit.	2	H319
Eye irritation	Eye Irrit.	2A	H319

Discovery and Applications

1-(2-Hydroxyethyl)-2-imidazolidinone, also known as hydroxyethyl urea, is a low-molecular-weight, water-soluble organic compound widely used in cosmetics, pharmaceuticals, and industrial applications due to its excellent moisturizing properties and role as a humectant. It is a substituted imidazolidinone derivative, structurally consisting of a five-membered ring (imidazolidinone) bearing a hydroxyethyl substituent at the nitrogen atom. The compound's amphiphilic nature and ability to form hydrogen bonds contribute to its functional versatility.

The discovery and development of 1-(2-hydroxyethyl)-2-imidazolidinone are tied to research on non-volatile humectants that improve water retention in formulations without causing irritation or sensitization. Its introduction into personal care products, particularly skin care formulations, was motivated by the need for ingredients that provide effective hydration comparable to glycerin or urea but with improved sensory characteristics and stability. Hydroxyethyl urea emerged as a solution offering similar efficacy in moisture retention while being less sticky and more cosmetically elegant.

In cosmetic applications, 1-(2-hydroxyethyl)-2-imidazolidinone serves as a humectant and skin-conditioning agent. It enhances the stratum corneum’s hydration by attracting and retaining water, which improves skin smoothness and elasticity. It is frequently included in moisturizers, lotions, creams, and hair care products. Its compatibility with a broad range of ingredients and stability across various pH levels make it an ideal additive in complex formulations. Moreover, unlike free urea, it is non-hygroscopic in the solid state, simplifying manufacturing and storage.

Pharmaceutical research has also explored this compound for its role in topical drug delivery systems. Its solubility-enhancing properties and low irritation potential make it suitable for formulations requiring prolonged skin contact. It can function as a solvent or co-solvent in transdermal delivery systems or dermatological preparations, often enhancing the penetration of active pharmaceutical ingredients.

From an industrial perspective, hydroxyethyl urea has been evaluated as a performance additive in coatings and adhesives. It contributes to moisture control and can act as a coalescing aid in waterborne polymer systems. In textile processing, it has been utilized as a softening agent or moisture regulator in fabric treatments.

Synthesis of 1-(2-hydroxyethyl)-2-imidazolidinone typically involves the reaction of ethylene glycol with urea or substituted ureas under controlled conditions. The process is efficient and scalable, supporting its commercial production. The resulting product is typically a white to off-white crystalline solid or a viscous liquid, depending on the formulation.

Toxicological assessments have shown that the compound has a favorable safety profile, with low skin and eye irritation potential and negligible systemic toxicity. Regulatory agencies have approved its use in a variety of applications, provided it meets established purity standards.

1-(2-Hydroxyethyl)-2-imidazolidinone exemplifies a class of functional small molecules that enhance both consumer product performance and user experience. Its established roles in moisturizing, solubilizing, and stabilizing formulations have secured its place as a valued ingredient in diverse sectors ranging from cosmetics to pharmaceuticals and industrial applications.

References

2024. Eco-friendly Fabrication of Perovskite Solar Cells: From Material Engineering to Recycling. Korean Journal of Chemical Engineering.
DOI: 10.1007/s11814-024-00331-x

1975. Electro-kinetic studies of cotton Part II: Measurement of surface potential at the interface between cellulose and solution of cross-linking agents. Colloid and Polymer Science.
DOI: 10.1007/bf01592268

1981. Cyclic urea and thiourea derivatives as inducers of murine erythroleukemia differentiation. Journal of Medicinal Chemistry.
DOI: 10.1021/jm00141a015