4-ethyl-2-hydroxy-3-methyl-2-cyclopenten-1-one

4-ethyl-2-hydroxy-3-methyl-2-cyclopenten-1-one is an oxygenated cyclopentenone derivative characterized by the molecular formula C₈H₁₂O₂. It appears as a constituent with a malty, sweet odor noted particularly at 1% concentration in propylene glycol. This compound is known by several synonyms including 2-cyclopenten-1-one, 4-ethyl-2-hydroxy-3-methyl- and 4-ethyl-2-hydroxy-3-methylcyclopent-2-en-1-one. It is naturally sourced primarily from roasted coffee beans, contributing to their complex aroma profile. For controlled vocabulary reference, see its PubChem entry, which catalogues detailed chemical information. The compound's sensory characteristics make it significant in studies of flavor chemistry rather than as a standalone flavor additive.

4-ethyl-2-hydroxy-3-methyl-2-cyclopenten-1-one occurs naturally in roasted coffee, where it plays a role in the malty and sweet aroma notes that define this complex food matrix. Its presence in natural substances and extractives classifies it for use primarily in analytical or research contexts, particularly in flavor chemistry. Usage levels for fragrance or flavor applications are not recommended due to regulatory status and lack of approved guidelines. According to FEMA (US) and other regional standards, this compound is categorized without specific allowances for direct application in consumer products, highlighting its importance mainly as a naturally occurring aroma component rather than a deliberately added ingredient.

This compound exhibits moderate water solubility, estimated around 1112 mg/L at 25 °C, supporting its partial miscibility in aqueous environments. It has a molecular weight of approximately 140.18 g/mol and an estimated octanol-water partition coefficient (log P) of about 0.62, indicating moderate lipophilicity. The vapor pressure is low, measured at 0.002 mmHg at 25 °C, suggesting limited volatility under ambient conditions. Its flash point is reported to be 226 °F (approximately 108 °C), indicating moderate thermal stability and low flammability risk. These physicochemical attributes impact formulation strategies, favoring applications where controlled aroma release and solubility are necessary, although practical use is limited by regulatory constraints.

(IUPAC):	Atomic Weights of the Elements 2011 (pdf)
Videos:	The Periodic Table of Videos
tgsc:	Atomic Weights use for this web site
(IUPAC):	Periodic Table of the Elements
HMDB (The Human Metabolome Database):	HMDB39673
FooDB:	FDB019302
VCF-Online:	VCF Volatile Compounds in Food
ChemSpider:	View

Safety information

Hazards identification
Classification of the substance or mixture
GHS Classification in accordance with 29 CFR 1910 (OSHA HCS)
None found.
GHS Label elements, including precautionary statements
Pictogram
Hazard statement(s)
None found.
Precautionary statement(s)
None found.
Oral/Parenteral Toxicity:
Not determined
Dermal Toxicity:
Not determined
Inhalation Toxicity:
Not determined

Safety in use information

Category:
natural substances and extractives
Recommendation for 4-ethyl-2-hydroxy-3-methyl-2-cyclopenten-1-one usage levels up to:
	not for fragrance use.
Recommendation for 4-ethyl-2-hydroxy-3-methyl-2-cyclopenten-1-one flavor usage levels up to:
	not for flavor use.

Safety references

EPI System: View

AIDS Citations:Search

Cancer Citations:Search

Toxicology Citations:Search

EPA ACToR:Toxicology Data

EPA Substance Registry Services (SRS):Registry

Laboratory Chemical Safety Summary :528704

National Institute of Allergy and Infectious Diseases:Data

4-ethyl-2-hydroxy-3-methylcyclopent-2-en-1-one