L-Menthone 70

Synthesis route :

Synthetic L-Menthone 70 is produced by a dehydrogenation of L-Menthol, with the presence of catalytic copper and chromium. A hydrogenation of Thymol, catalysed by palladium, also allows to obtain a racemic mixture of Menthone® isomers.

Synthesis precursor :

Menthone® is a precursor to the synthesis of Menthol by catalytic hydrogenation, forming NeoMenthol and Menthol.

Isomerism :

Menthone® is a mixture of two pairs of dextrorotatory and laevorotatory isomers: Menthone® and Isomenthone. Isomenthone has a more moldy smell than Menthone®. These two enantiomers have a strong tendency to interchange, making it difficult to separate them from synthetic Menthone® or from an essential oil. In the synthesis of Menthone®, the isomers of the molecules can be selected by changing the synthesis conditions or the starting reagent (for example, dehydrogenated or oxidized L-Menthol gives a mixture of L-Menthone® and D-isomenthone). Linalool, Nerol, Geraniol and Terpineol are some of the constitutional isomers of Menthone®. Nevertheless, they have a much more floral or terpenic smell, far from the frosty mint note of Menthone®.