Isomenthone

Synthesis route :

Isomenthone can be obtained synthetically from Menthol or Thymol. From Menthol, an oxidation reaction of the alcohol function is carried out to obtain a ketone function. The choice of the Menthol isomer (for example L-Menthol) is important to guide the nature of the final product. From Thymol, a hydrogenation in the presence of a palladium on carbon catalyst is necessary. In all cases, several isomers are obtained at the end of the reaction. These can be separated by a fractional distillation to collect the isomers of interest only.

Synthesis precursor :

Menthone® and Isomenthone are used to synthesize Menthol isomers by hydrogenation. The choice of the starting isomer is important. For example, using a laevorotatory Isomenthone leads to the formation of laevorotatory Neomenthol and dextrorotatory Menthol.

Isomerism :

Isomenthone is a diastereoisomer of Menthone®. Both also have a pair of enantiomers : Menthone® have a much colder and alimentary smell and Isomenthone are greener and more terpenic. These molecules are difficult to obtain with a high purity because the isomers have a tendency to interconvert. In perfumery, the most used Isomenthone is its enantiomers mixture. In addition, Isomenthone is a constitutional isomer of Borneol in particular. Both provide a refreshing effect in compositions, but Isomenthone is more suitable for mint reconstitutions.