Menthol is a cyclic monoterpene alcohol which is an important ingredient in more than 100
essential oils. Its presence is best known in various plants that belong to the mint genus
(Mentha). Menthol is obtained primarily from essential peppermint oil by steam distillation.
At room temperature it is solid and in the form of white or colorless crystals.
Camphor tree belongs to the laurel family (Lauraceae) and it is widespread in East and South
Asia. It is one of the most important natural sources of camphor. Camphor is formed in cells
that are distributed throughout the entire tree. Natural camphor is obtained by steam
distillation of camphor wood, followed by crystallization or sublimation. It appears in the
form of colorless or white crystals with a strong and distinctive smell.
The aim of our thesis was to test the effect of minor changes in structures of menthol and
camphor on the smell of products of chemical reactions. In the experimental part, we first
successfully reduced camphor. Then using classical methods of organic chemistry, we
performed six syntheses, the products of which were volatile derivatives of reduced camphor
or menthol. Column adsorption chromatography was used to isolate and purify our desired
products. The success of the reactions and the identity of the products were verified by using
instrumental methods of analysis, in our case nuclear magnetic resonance spectroscopy and
infrared spectroscopy. We did not use the mass spectrometry devices at The Chair of
Pharmaceutical Chemistry at the Faculty of Pharmacy due to poor ionization of the products.
By odor analysis we have made olfactory evaluation of menthol, camphor, reduced camphor
and two of our synthesis products. The respondents had to evaluate the pleasantness and
strength of the samples. Finally, they had to write down the associations that came to their
mind for all individual samples. Most of the test subjects rated their smell as pleasant.
Respondents rated the smell of menthol as the most intense. In addition, we formed a
hydrogel which is a simple semi-solid cosmetic product. It contained camphor and menthol.
When applied to the skin, a cooling sensation appeared. After a few weeks, we detected an
overgrowth of microorganisms due to lack of preservative and consequent poor
antimicrobial protection.
|
