Limonene
Chemical name	1-methyl-4-prop-1-en-2-yl-cyclohexene
Synonyms	4-isopropenyl-1-methylcyclohexene Racemic: DL-limonene; dipentene
Chemical formula	C10H16
Molecular mass	136.24 g/mol
Melting point	-95 °C
Boiling point	176 °C
Density	0.8411 g/cm3
Refractive index	1.4730
Flash point	50°C
CAS number9	138-86-3
EINECS number9	205-341-0
PubChem	22311 (dipentene)
PubChem	439250 ((-)-Limonene)
PubChem	440917 ((+)-Limonene)
SMILES	CC1=CCC(C(=C)(C))CC1
Disclaimer and references

Limonene is a hydrocarbon, classed as a terpene. It is a clear, colourless liquid at room temperatures with an extremely strong smell of oranges. It takes its name from the lemon, as the rind of the lemon, like other citrus fruits, contains considerable amounts of this chemical compound, which is responsible for much of their smell. Limonene is a chiral molecule, and as is common with such forms, biological sources produce one specific enantiomer: the principal industrial source, citrus fruit, contains D-limonene ((+)-limonene), which is the (R)-enantiomer (CAS number 5989-27-5, EINECS number 227-813-5). Racemic limonene is known as dipentene.^[1] Image File history File links Download high-resolution version (819x1932, 12 KB) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Limonene ... Image File history File links Download high-resolution version (970x1170, 105 KB) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Limonene ... IUPAC nomenclature is a system of naming chemical compounds and of describing the science of chemistry in general. ... A chemical formula (also called molecular formula) is a concise way of expressing information about the atoms that constitute a particular chemical compound. ... The molecular mass (abbreviated MM) of a substance, called molecular weight and abbreviated as MW, is the mass of one molecule of that substance, relative to the unified atomic mass unit u (equal to 1/12 the mass of one atom of carbon-12). ... The melting point of a solid is the temperature at which it changes state from solid to liquid. ... The boiling point of a substance is the temperature at which it can change its state from a liquid to a gas throughout the bulk of the liquid at a given pressure. ... Density (symbol: ρ - Greek: rho) is a measure of mass per volume. ... The refractive index (or index of refraction) of a material is the factor by which the phase velocity of electromagnetic radiation is slowed in that material, relative to its velocity in a vacuum. ... The flash point of a flammable liquid is the lowest temperature at which it can form an ignitable mixture with air. ... CAS registry numbers are unique numerical identifiers for chemical compounds, polymers, biological sequences, mixtures and alloys. ... The EINECS number (for European Inventory of Existing Chemical Substances) is a registry number given to each chemical substance commercially available in the European Union between 1 January 1971 and 18 September 1981. ... PubChem is a database of chemical molecules . ... PubChem is a database of chemical molecules . ... PubChem is a database of chemical molecules . ... The simplified molecular input line entry specification or SMILES is a specification for unambiguously describing the structure of chemical molecules using short ASCII strings. ... Hydrocarbons are refined at oil refineries and processed at chemical plants In chemistry, a hydrocarbon is any chemical compound that consists only of the elements carbon (C) and hydrogen (H). ... Terpenes are a large and varied class of hydrocarbons, produced primarily by a wide variety of plants, particularly conifers, though also by some animals. ... Percentages are relative to US RDI values for adults. ... Binomial name Citrus × limon (L.) Burm. ... Species & major hybrids Species Citrus maxima- Pomelo Citrus medica- Citron Citrus reticulata- Mandarin & Tangerine Major hybrids Citrus × sinensis- Sweet Orange Citrus × aurantium- Bitter Orange Citrus × paradisi- Grapefruit Citrus × limon- Lemon Citrus × latifolia- Persian lime Citrus × aurantifolia- Key lime See also main text for other hybrids Citrus is a common term... Chirality refers to several phenomena, all having to do with objects that differ from their mirror image. ... In chemistry, enantiomers are stereoisomers that are mirror images of each other. ... In chemistry, enantiomers are stereoisomers that are mirror images of each other. ... CAS registry numbers are unique numerical identifiers for chemical compounds, polymers, biological sequences, mixtures and alloys. ... The EINECS number (for European Inventory of Existing Chemical Substances) is a registry number given to each chemical substance commercially available in the European Union between 1 January 1971 and 18 September 1981. ... In chemistry, a racemate is a mixture of equal amounts of left- and right-handed stereoisomers of a chiral molecule. ...

Uses

As the main odour constituent of citrus (plant family Rutaceae), d-limonene is used in food manufacturing as a flavoring, and added to cleaning products such as hand cleansers to give a lemon-orange fragrance. See: orange oil. Species & major hybrids Species Citrus maxima- Pomelo Citrus medica- Citron Citrus reticulata- Mandarin & Tangerine Major hybrids Citrus × sinensis- Sweet Orange Citrus × aurantium- Bitter Orange Citrus × paradisi- Grapefruit Citrus × limon- Lemon Citrus × latifolia- Persian lime Citrus × aurantifolia- Key lime See also main text for other hybrids Citrus is a common term... Genera About 160 genera; selected important genera: Amyris - West Indian Sandalwood Choisya - Mexican orange Citrus - Citrus Dictamnus - Burning-bush Fortunella - Kumquat Melicope - Corkwood, Alani Murraya - Curry tree Phellodendron - Cork-trees Poncirus - Trifoliate orange Ptelea - Hoptree Ruta - Rue Skimmia - Skimmia Tetradium (Euodia) - Euodias Zanthoxylum - Toothache trees Rutaceae is a family of... Flavouring (or flavoring) is a product which is added to food in order to change or augment its taste. ... Odor receptors on the antennae of a Luna moth An odor is the object of perception of the sense of olfaction. ... Orange oil is also know as d-limonene. ...

Limonene is increasingly being used as an environmentally friendly alternative to mineral oils as a solvent for cleaning purposes, such as the removal of oil from machine parts, being more easily biodegradable than mineral oils, and produced from a renewable source (citrus oil, as a byproduct of orange juice manufacture.) Limonene works as paint stripper when applied to painted wood. The (R)-enantiomer is also used as botanical insecticide. Mineral oil or liquid petrolatum is a by-product in the distillation of petroleum to produce gasoline. ... A solvent is a fluid phase (liquid, gas, or plasma) that dissolves a solid, liquid, or gaseous solute, resulting in a solution. ... Biodegradation is the decomposition of material by microorganisms. ... For other uses, see Orange juice (disambiguation). ... In chemistry, enantiomers are stereoisomers that are mirror images of each other. ... Botany is the scientific study of plant life. ... A insecticide is a pesticide used against insects in all development forms. ...

The (S)-enantiomer, also known as l-limonene (CAS number 5989-54-8, EINECS number 227-815-6), is used as a fragrance in some cleaning products. In contrast to the citrus (orange-lemon) scent (see above) of d-limonene, the enantiomer l-limonene has a piney, turpentine-like odor. In chemistry, enantiomers are stereoisomers that are mirror images of each other. ... CAS registry numbers are unique numerical identifiers for chemical compounds, polymers, biological sequences, mixtures and alloys. ... The EINECS number (for European Inventory of Existing Chemical Substances) is a registry number given to each chemical substance commercially available in the European Union between 1 January 1971 and 18 September 1981. ... For the band, click Turpentine (band). ...

Chemistry

Limonene is a relatively stable terpene, which can be distilled without decomposition, though it forms isoprene when passed over a hot metal filament. It is easily oxidised in moist air to carveol and carvone^[4] . Oxidation using sulfur leads to p-cymene and a sulfide. Isoprene is a common synonym for the chemical compound 2-methyl-1,3-butadiene. ... Carveol is a natural terpenoid alcohol that is a constituent of spearmint oil. ... // Carvone Carvone is a member of a family of chemicals called terpenoids. ... Cymene, or p-cymene, is a naturally occurring aromatic organic compound. ... A thioether (also known as a sulfide) is a functional group in organic chemistry that has the structure R-S-R, where R is any organic group. ...

Limonene occurs naturally as the (R)-enantiomer, but it can be racemised to dipentene simply by heating at 300 °C. When warmed with mineral acid, limonene forms the conjugated diene terpinene, which can itself easily be oxidised to p-cymene, an aromatic hydrocarbon. Evidence for this includes the formation of Diels-Alder α-terpinene adducts when limonene is heated with maleic anhydride. In chemistry, enantiomers are stereoisomers that are mirror images of each other. ... Headline text Happy Hannukah and a happy new year!! POOP e Butt ... A chemically conjugated system, is a system of atoms covalently bonded with alternating single and double bonds (e. ... The terpinenes are three isomeric hydrocarbons that are classified as terpenes. ... An aromatic hydrocarbon (abbreviated as AH), or arene is a hydrocarbon, the molecular structure of which incorporates one or more planar sets of six carbon atoms that are connected by delocalised electrons numbering the same as if they consisted of alternating single and double covalent bonds. ... The Diels-Alder reaction The Diels-Alder reaction is an organic chemical reaction (specifically, a cycloaddition) between a conjugated diene and a substituted alkene, commonly termed the dienophile, to form a substituted cyclohexene system. ... R-phrases , , S-phrases , , , , Flash point 102 °C RTECS number UE5950000 Supplementary data page Structure and properties n, εr, etc. ...

It is possible to effect reaction at one of the double bonds selectively. Anhydrous hydrogen chloride reacts preferentially at the disubstituted alkene, whereas epoxidation with MCPBA occurs at the trisubstituted alkene. In both cases the second C=C double bond can be made to react if desired. R-phrases , S-phrases , , , , Flash point non-flammable Supplementary data page Structure and properties n, εr, etc. ... An epoxide is a cyclic ether with only three ring atoms. ... Chemical structure of meta-chloroperoxybenzoic acid meta-Chloroperoxybenzoic acid (mCPBA) is a peroxy acid with chemical formula C7H5ClO3 and CAS number 937-14-4. ...

Biosynthesis

Limonene is formed from geranyl pyrophosphate, via cyclisation of a neryl carbocation or its equivalent as shown.⁽⁵⁾ The final step involves loss of a proton from the cation to form the alkene. Biosynthesis is a phenomenon where chemical compounds are produced from simpler reagents. ... Chemical structure of geranyl pyrophosphate. ... Nerol is a natural monoterpene found in many essential oils. ... A carbocation is an ion with a positively-charged carbon atom. ... The chemical structure of ethylene, the simplest alkene. ...

Image File history File links Download high resolution version (924x233, 23 KB) Summary The biosynthesis of limonene, drawn in ChemDraw by User:Walkerma in September 2005. ...

Safety information

General

Limonene and its oxidation products are skin irritants, and limonene-1,2-oxide (formed by aerial oxidation) is a known skin sensitizer. Most reported cases of irritation have involved long-term industrial exposure to the pure compound, e.g. during degreasing or the preparation of paints. However a study of patients presenting dermatitis showed that 3% were sensitized to limonene.⁽⁶⁾ Dermatitis is a term literally meaning inflammation of the skin. It is usually used to refer to eczema, which is also known as Dermatitis eczema. ...

Limonene causes renal cancer in male rats, but not in female rats or in mice of either sex, due to binding of the metabolite limonene-1,2-oxide to α_2u-globulin, a protein produced only by male rats. There is no evidence for carcinogenicity or genotoxicity in humans. The IARC classifies d-limonene under Class 3: not classifiable as to its carcinogenicity to humans. [1] Renal cell carcinoma, also known by a gurnistical tumor, is the most common form of kidney cancer arising from the renal tubule. ... A metabolite is the product of metabolism. ... Globulin is one of the two types of serum proteins, the other being albumin. ... A representation of the 3D structure of myoglobin, showing coloured alpha helices. ... In pathology, a carcinogen is any substance or agent that promotes cancer. ... Categories: Move to Wiktionary | Biochemistry stubs ... The International Agency for Research on Cancer (IARC, or CIRC in its French acronym) is an intergovernmental agency forming part of the World Health Organisation of the United Nations. ...

Europe

Limonene is listed in annex 1 of the directive 67/548/EEC under index number 601-029-00-7 [2]. The pure substance is classified as irritant (Xi) and dangerous for the environment (N). The following risk and safety statements are obligatory: Council Directive 67/548/EEC of 27 June 1967 on the approximation of laws, regulations and administrative provisions relating to the classification, packaging and labelling of dangerous substances (as amended) is the main source of European Union law concerning chemical safety. ... Risk and Safety Statements, also known as R/S statements, R/S numbers, R/S phrases, and R/S sentences, is a system of hazard codes and phrases for labeling dangerous chemicals and compounds. ...

• R10: Flammable.
• R38: Irritating to skin.
• R43: May cause sensitization by skin contact.
• R50/53: Very toxic to aquatic organisms, may cause long-term adverse effects in the aquatic environment.
• S2: Keep out of the reach of children.
• S24: Avoid contact with skin.
• S37: Wear suitable non-latex gloves.
• S60: This material and its container must be disposed of as hazardous waste.
• S61: Avoid release to the environment. Refer to special instructions/Safety data sheets.

Limonene is not specifically mentioned in directive 1999/45/EC, and so the labelling of preparations containing this compound is at the discretion of the manufacturer.

Canada

Limonene is classified [3] under the categories

• B3: Combustible liquid
• D2B: Toxic material causing other toxic effects

The presence of limonene in a preparation at a concentration greater than 1.0% must be disclosed.

Australia

Limonene is listed in Class 3, flammable liquids, Packing Group III, under the Australian Dangerous Goods Code.

Notes and References

1. J. L. Simonsen, The Terpenes Volume I (2nd edition), Cambridge University Press, 1947.
2. E. E. Turner, M. M. Harris, Organic Chemistry, Longmans, Green & Co., London, 1952.
3. Wallach, Annalen der Chemie, 246, 221 (1888).
4. Blumann & Zeitschel, Berichte, 47, 2623 (1914).
5. J. Mann, R. S. Davidson, J. B. Hobbs, D. V. Banthorpe, J. B. Harborne, Natural Products, pp308-309, Addison Wesley Longman Ltd., Harlow, UK, 1994. ISBN 0-582-06009-5.
6. IARC Monographs on the evaluation of carcinogenic risks to humans 1999, 73, 307-27.
7. Source: European Chemicals Bureau.
8. Source: CSST Workplace Hazardous Materials Information System.
9. The CAS and EINECS numbers in the table are for the racemic mixture: the relevant numbers for the two enantiomers are given in the text.
10. M. Matura et al., J. Am. Acad. Dermatol. 2002, 33, 126-27.

In chemistry, a racemate is a mixture of equal amounts of left- and right-handed stereoisomers of a chiral molecule. ... In chemistry two stereoisomers are said to be enantiomers if one can be superimposed on the mirror image of the other, and vice versa. ...

External links

• Detailed description of d-limonene from Biochem Corp.

• Link page to external chemical sources.