imonene is a relatively stable terpene and can be distilled without decomposition, although at elevated temperatures it cracks to form isoprene.[3] It oxidizes easily in moist air to produce carveol, carvone, and limonene oxide.[4] With sulfur, it undergoes dehydrogenation to p-cymene.[5]
Limonene occurs naturally as the (R)-enantiomer, but racemizes to dipentene at 300 °C. When warmed with mineral acid, limonene isomerizes to the conjugated diene α-terpinene (which can also easily be converted to p-cymene). Evidence for this isomerization includes the formation of Diels-Alder adducts between α-terpinene adducts and maleic anhydride.
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 another synthetic method Markovnikov addition of trifluoroacetic acid followed by hydrolysis of the acetate gives terpineol.