2-Pentyl-3-methyl-2-cyclopenten-1-one

Synonym(s):3-Methyl-2-pentyl-2-cyclopenten-1-one

CAS NO.：1128-08-1
Empirical Formula: C11H18O
Molecular Weight: 166.26
MDL number: MFCD00036480
EINECS: 214-434-5
SAFETY DATA SHEET (SDS)
Update Date: 2026-05-11 16:31:51

2-Pentyl-3-methyl-2-cyclopenten-1-one Structural

What is 2-Pentyl-3-methyl-2-cyclopenten-1-one?

Chemical properties

2-Pentyl-3-methyl-2-cyclopenten-1-one is a colorless, slightly viscous liquid with a typical jasmine odor, resembling that of the naturally occurring (Z)-jasmone. Dihydrojasmone is produced by an acid-catalyzed rearrangement of 4-methyl-??-decalactone, which is readily obtained by radical addition of 2-octanol to acrylic acid.
Dihydrojasmone is used in perfumery in jasmine bases and, more generally, in floral and fruity fragrances.

Chemical properties

3-Methyl-2-(n-pentanyl)-2-cyclopenten-1-one has a fresh, fruity, jasmine odor with woody and herbal nuances.

Occurrence

Has apparently not been reported to occur in nature.

Preparation

Hexyl bromide plus levulinic ester yields a lactone, which is reacted with polyphosphoric acid or phosphorus pentoxide to produce hydrojasmone.

Definition

ChEBI: 3-methyl-2-pentylcyclopent-2-en-1-one is a cyclic ketone.

Taste threshold values

Taste characteristics at 10 ppm: sweet, floral, green, herbal with a citrus nuance.

Synthesis Reference(s)

Canadian Journal of Chemistry, 56, p. 2301, 1978 DOI: 10.1139/v78-379
Journal of the American Chemical Society, 92, p. 7428, 1970 DOI: 10.1021/ja00728a029

Properties of 2-Pentyl-3-methyl-2-cyclopenten-1-one

Boiling point:	120-121 °C12 mm Hg(lit.)
Density	0.916 g/mL at 25 °C(lit.)
refractive index	n20/D 1.479(lit.)
FEMA	3763 \| 3-METHYL-2-(N-PENTANYL)-2-CYCLOPENTEN-1-ONE
Flash point:	230 °F
storage temp.	Store at -20°C
solubility	DMSO:100.0(Max Conc. mg/mL);601.45(Max Conc. mM)
form	clear liquid
color	A colourless, slightly oily liquid with a floral-like odour
Specific Gravity	0.914～0.916 (20/4℃)
Odor	at 100.00 %. fresh outdoor jasmin myrrh woody spice herbal
JECFA Number	1406
BRN	1906471
CAS DataBase Reference	1128-08-1(CAS DataBase Reference)
NIST Chemistry Reference	Dihydrojasmone(1128-08-1)
EPA Substance Registry System	2-Cyclopenten-1-one, 3-methyl-2-pentyl- (1128-08-1)

Safety information for 2-Pentyl-3-methyl-2-cyclopenten-1-one

Signal word	Warning
Pictogram(s)	Exclamation Mark Irritant GHS07
GHS Hazard Statements	H303:Acute toxicity,oral
Precautionary Statement Codes	P270:Do not eat, drink or smoke when using this product. P301+P312:IF SWALLOWED: call a POISON CENTER or doctor/physician IF you feel unwell. P403:Store in a well-ventilated place.