3-methylcyclopent-2-en-1-one

Synonym(s):3-Methyl-2-cyclopentenone

May be prepared by dehydrohalogenation of 2-chloro-l-methylcyclopentan-3-one.

clear light yellow to yellow-brownish liquid

1-Methyl-1-cyclopenten-3-one has a sweet-floral, warm-spicy and diffusive yet quite tenacious odor.

Reported found in roasted onion, cooked pork, black tea, soybean and dried bonito

It is an important raw material and intermediate used in Organic Synthesis, Pharmaceuticals, Agrochemicals.

3-Methyl-2-cyclopentenone was used in the synthesis of 2-hydroxy-3-methyl-2-cyclopentenone.

By dehydrohalogenation of 2-chloro-1-methyl-cyclopentan-3-one.

ChEBI: 3-Methyl-2-cyclopenten-1-one is a cyclic ketone.

Journal of the American Chemical Society, 101, p. 494, 1979 DOI: 10.1021/ja00496a044
The Journal of Organic Chemistry, 55, p. 371, 1990

3-Methyl-2-cyclopenten-1-one is a component of smoke flavoring.

Melting point:	3-5 °C (lit.)
Boiling point:	74 °C/15 mmHg (lit.)
Density	0.980 g/mL at 20 °C 0.971 g/mL at 25 °C (lit.)
refractive index	n20/D 1.488(lit.)
FEMA	3435 \| 1-METHYL-1-CYCLOPENTEN-3-ONE
Flash point:	150 °F
storage temp.	2-8°C
solubility	Soluble in DMSO
form	Liquid
color	Clear light yellow to yellow-brown
Odor	at 1.00 % in dipropylene glycol. sweet fruity fatty
PH	4.9 (10g/l, H2O, 20℃)
Water Solubility	miscible
JECFA Number	1105
BRN	1280476
CAS DataBase Reference	2758-18-1(CAS DataBase Reference)
NIST Chemistry Reference	2-Cyclopenten-1-one, 3-methyl-(2758-18-1)
EPA Substance Registry System	3-Methyl-2-cyclopenten-1-one (2758-18-1)

Signal word	Warning
Pictogram(s)	Exclamation Mark Irritant GHS07
GHS Hazard Statements	H227:Flammable liquids
Precautionary Statement Codes	P403+P235:Store in a well-ventilated place. Keep cool.