Limonene

Limonene
	Limonene extracted from orange peel
Names
	Preferred IUPAC name 1-Methyl-4-(prop-1-en-2-yl)cyclohex-1-ene
	Other names 1-Methyl-4-(1-methylethenyl)cyclohexene; 4-Isopropenyl-1-methylcyclohexene; p-Menth-1,8-diene; Racemic: DL-Limonene; Dipentene
Identifiers
CAS Number	138-86-3 (R/S) ; 5989-27-5 (R) ; 5989-54-8 (S) ;
3D model (JSmol)	Interactive image;
ChEBI	CHEBI:15384 ;
ChEMBL	ChEMBL449062 (R) ;
ChemSpider	20939 (R/S) ; 388386 (S) ; 389747 (R) ;
ECHA InfoCard	100.004.856
KEGG	D00194 ;
PubChem CID	22311 (R/S); 439250 (S);
UNII	9MC3I34447 (R/S) ; GFD7C86Q1W (R) ; 47MAJ1Y2NE (S) ;
CompTox Dashboard (EPA)	DTXSID2029612 ;
	InChI InChI=1S/C10H16/c1-8(2)10-6-4-9(3)5-7-10/h4,10H,1,5-7H2,2-3H3 Key: XMGQYMWWDOXHJM-UHFFFAOYSA-N ;
	SMILES CC1=CCC(CC1)C(=C)C;
Properties
Chemical formula	C10H16
Molar mass	136.238 g·mol−1
Appearance	colorless liquid
Odor	Orange
Density	0.8411 g/cm3
Melting point	−74.35 °C (−101.83 °F; 198.80 K)
Boiling point	176 °C (349 °F; 449 K)
Solubility in water	Insoluble
Solubility	Miscible with benzene, chloroform, ether, CS2, and oils ; soluble in CCl4
Chiral rotation ([α]D)	87–102°
Refractive index (nD)	1.4727
Thermochemistry
Std enthalpy of; combustion (ΔcH⦵298)	−6.128 MJ mol−1
Hazards
	Occupational safety and health (OHS/OSH):
Main hazards	Skin sensitizer / Contact dermatitis – After aspiration, pulmonary oedema, pneumonitis, and death
	GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H226, H304, H315, H317, H410
Precautionary statements	P210, P233, P235, P240, P241, P242, P243, P261, P264, P272, P273, P280, P301+P330+P331, P302+P352, P303+P361+P353, P304+P340, P312, P333+P313, P362, P370+P378, P391, P403+P233, P405, P501
NFPA 704 (fire diamond)	2 2 0
Flash point	50 °C (122 °F; 323 K)
Autoignition; temperature	237 °C (459 °F; 510 K)
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Limonene (/ˈlɪmənˌiːn/) is a colorless liquid aliphatic hydrocarbon classified as a cyclic monoterpene, and is the major component in the essential oil of citrus fruit peels. The (+)-isomer, occurring more commonly in nature as the fragrance of oranges, is a flavoring agent in food manufacturing. It is also used in chemical synthesis as a precursor to carvone and as a renewables-based solvent in cleaning products. The less common (−)-isomer has a piny, turpentine-like odor, and is found in the edible parts of such plants as caraway, dill, and bergamot orange plants.

Limonene takes its name from Italian limone ("lemon"). Limonene is a chiral molecule, and biological sources produce one enantiomer: the principal industrial source, citrus fruit, contains (+)-limonene (d-limonene), which is the (R)-enantiomer. (+)-Limonene is obtained commercially from citrus fruits through two primary methods: centrifugal separation or steam distillation.