View source for Alpha-Pinene

{{lowercase|alpha-Pinene}}
{{Chembox/Top|alpha-Pinene}} 
{{Chembox/Image|AlphaPinene.png}}
{{Chembox/SectGeneral}}
{{Chembox/IUPACName|(1''S'',5''S''-2,6,6-trimethyl<br/>bicyclo<nowiki>[3.1.1]</nowiki>hept-2-ene<br/>((&minus;)-Pinene)}} 
{{Chembox/OtherNames|}} 
{{Chembox/Formula|C<sub>10</sub>H<sub>16</sub>}} 
{{Chembox/SMILES|<nowiki>CC1(C)[C@H]2C(C)=CC[C@@H]1[C@]2(C)C</nowiki>}} 
{{Chembox/MolarMass|136.23}}
{{Chembox/Appearance|Clear, colourless liquid}}
| [[CAS registry number|CAS number]]
|[80-56-8] (unspecified)<br/>[7785-70-8] (+)-α-Pinene<br/>[7785-26-4] (&minus;)-α-Pinene)
|-
{{Chembox/SectProperties}}
{{Chembox/Density|0.858|g/mL|liquid at 20° C}}
| [[Soluble|Solubility]] in [[Water (molecule)|water]]
| Very low
|-
{{Chembox/Solubility|acetic acid|miscible}}
{{Chembox/Solubility|ethanol|miscible}}
{{Chembox/Solubility|acetone|miscible}}
{{Chembox/MeltingPt|&minus;64 °C (209 K)}} 
{{Chembox/BoilingPt|155 °C (428 K)}} 
{{Chembox/SpecificRotation|&minus;50.7°|(1''S'',5''S''-Pinene)}} 
{{Chembox/SectHazards}} <!--  Summary only, MSDS provides more complete information -->
{{Chembox/MainHazards| flammable}}
<!-- {{Chembox/EUClass|?}} alternative to the above section -->
{{Chembox/NFPA|1|2|0}} 
{{Chembox/RPhrases|10-20/21/22-36/37/38-43-51}}
{{Chembox/SPhrases|16-26-36-37-60-61}}
{{Chembox/RTECSNo|DT7000000 (unspec. isomer)}}
{{Chembox/SectDataPage}}
{{Chembox/SectRelated}}
{{Chembox/RelatedX|alkene|[[Beta-Pinene]], [[Camphene]]<br/>[[3-Carene]], [[Bornene]]<br/>[[Limonene]]}}
{{Chembox/RelatedCpds|[[Borneol]], [[Camphor]]<br/>[[Alpha-Terpineol]]}}
{{Chembox/Bottom}}
'''α-Pinene''' is an [[organic compound]] of the [[terpene]] class, one of two isomers of [[pinene]].<ref>Simonsen, J. L. (1957) ''The Terpenes (2nd edition)'' Vol. 2 Cambridge:Cambridge University Press, pp 105-191.</ref>  It is an [[alkene]] and it contains a reactive [[Cyclobutane|four-membered ring]].  It is found in the oils of many species of many [[Pinophyta|coniferous]] trees, notably the [[pine]].  It is also found in the essential oil of [[rosemary]] (''Rosmarinus officinalis'').<ref>PDR for Herbal Medicine.  Montvale, NJ:  Medical Economics Company.  p. 1100</ref>  Both [[enantiomer]]s are known in nature; 1''S'',5''S''- or (&minus;)-α-pinene is more common in European pines, whereas the 1''R'',5''R''- or (+)-α-isomer is more common in North America.  The racemic mixture is present in some oils such as [[eucalyptus]] oil.

==Chemical properties==
===General reactivity===
The four-membered ring in α-pinene '''1''' makes it a reactive [[hydrocarbon]], prone to skeletal rearrangements such as the [[Wagner-Meerwein rearrangement]].  For example, attempts to perform hydration or [[hydrogen halide]] addition with the alkene functionality typically lead to rearranged products. of under acidic conditions.  With concentrated [[sulfuric acid]] and [[ethanol]] the major products are [[terpineol]] '''2''' and its ethyl [[ether]] '''3''', while glacial [[acetic acid]] gives the corresponding [[acetate]] [[ester]] '''4'''. With dilute acids, [[terpin hydrate]] '''5''' becomes the major product.

With one molar equivalent of [[Hydrogen chloride|anhydrous HCl]], the simple addition product '''6a''' can be formed at low temperature in the presence of [[Diethyl ether|ether]], but it is very unstable.  At normal temperatures, or if no ether is present, the major product is [[bornyl chloride]] '''6b''', along with a small amount of [[fenchyl alcohol|fenchyl]] chloride '''6c'''.<ref>Richter, G. H. (1945) ''Textbook of Organic Chemistry'',  2nd ed., John Wiley & Sons., New York, PP 663-666.</ref>  For many years '''6b''' (also called "artificial camphor") was referred to as "pinene hydrochloride", until it was confirmed as identical with bornyl chloride made from [[camphene]].  If more HCl is used, [[:Wiktionary:achiral|achiral]] '''7''' ([[dipentene]] hydrochloride) is the major product along with some '''6b'''.  [[Nitrosyl chloride]] followed by base leads to the [[oxime]] 8 which can be reduced to "pinylamine" '''9'''.  Both '''8''' and '''9''' are stable compounds containing an intact four-membered ring, and these compounds helped greatly in identifying this important component of the pinene skeleton.<ref>[[Lavoslav Ružička|Ruzicka]] & Trebler, ''Helv. Chim. Acta.'' '''1921''', ''4'', 566.</ref>

A variety of reagents such as [[iodine]] or [[Phosphorus trichloride|PCl<sub>3</sub>]] cause [[Aromaticity|aromatisation]], leading to [[p-Cymene|p-cymene]] '''10'''.

[[Image:alphaPinene_rxns.png|450px|Some general reactions of alpha-pinene]]

==References==
{{reflist|2}}

[[Category:Terpenes and terpenoids]]
[[Category:Alkenes]]

[[be:Альфапінен]]
[[da:Alfa-pinen]]
[[pl:Alfa-pinen]]
{{WikiDoc Help Menu}}