Menthone

[3] Menthone is structurally related to menthol, which has a secondary alcohol (>C-OH) in place of the carbon-oxygen double bond (carbonyl group) projecting from the cyclohexane ring.

[citation needed] The structure 2-isopropyl-5-methylcyclohexanone has two asymmetric carbon centers, one at each attachment point of the two alkyl group substituents, the isopropyl in the 2-position and the methyl in the 5-position of the cyclohexane framework.

[9][better source needed] The spatial arrangement of atoms—the absolute configuration—at these two points are designated by the descriptors R (Latin, rectus, right) or S (L., sinister, left) based on the Cahn–Ingold–Prelog priority rules.

[dubious – discuss][8][verification needed] Menthone can easily be converted to isomenthone and vice versa via a reversible epimerization reaction via an enol intermediate, which changes the direction of optical rotation, so that l-menthone becomes d-isomenthone, and d-menthone becomes l-isomenthone.

][9] Menthone was one of the original substrates reported in the discovery of the still widely used synthetic organic chemistry transformation, the Baeyer-Villiger (B-V) oxidation,[13] as reported by Adolf Von Baeyer and Victor Villiger in 1899; Baeyer and Villiger noted that menthone reacted with monopersulfuric acid to produce the corresponding oxacycloheptane (oxepane-type) lactone, with an oxygen atom inserted between the carbonyl carbon and the ring carbon attached to the isopropyl substituent.

[15][non-primary source needed] Beckmann's inferences from his results situated menthone as a crucial player in a great mechanistic discovery in organic chemistry.

[citation needed] He postulated that this occurred through an intermediate enol—a tautomer of the ketone—such that the original absolute configuration of that carbon atom changed as its geometry went from terahedral to trigonal planar.

l-Menthone
l -Menthone