Piperitone is a natural monoterpene ketone which is a component of some . Both , the D-form and the L-form, are known. The D-form has a peppermint-like aroma and has been isolated from the oils of plants from the genera Cymbopogon, Andropogon, and Mentha.
Occurrence
Piperitone is found in many
essential oils, including over thirty species of the genus
Eucalyptus. High levels are present in certain species of
Eucalyptus and
Mentha.
In the genus Eucalyptus, the highest concentrations are found in
Eucalyptus dives.
Both
occur naturally. In Eucalyptus species, (-)-piperitone is present; in mint species, (+)-piperitone is found; and some plants contain
racemate piperitone.
Properties
Piperitone is a colorless liquid with a distinct
peppermint odor.
Production
Piperitone can be synthesized from isopropyl acetoacetate and 3-buten-2-one.
The primary source of D/L-piperitone is from Eucalyptus dives, produced mainly in South Africa.[Boland, D.J., Brophy, J.J., and A.P.N. House, Eucalyptus Leaf Oils, 1991, ]
Reactions
Piperitone is used as the principal raw material for the production of synthetic
menthol and
thymol.
The reduction to menthol is achieved using hydrogen and a
nickel catalyst. Oxidation to thymol is accomplished with iron(III) chloride and
acetic acid. It also forms adducts with
benzaldehyde and
hydroxylamine (an
oxime), which were historically useful for compound identification by the melting points of the derivatives.
Under light exposure, piperitone undergoes photodimerization, forming a polycyclic compound with a
cyclobutane ring.
