The Preparation of L-menthol by Organic Synthesis has a Promising Prospect
Menthol, the scientific name is 5-methyl-2-isopropylcyclohexanol. It is an important cooling compound. Menthol has 3 hand centers and a total of 8 stereoisomers. Among them, L-menthol has a light and sweet pungent odor and has a strong cooling effect; D-menthol has a pungent odor and has almost no cooling effect.
The mechanism of cooling effect of L-menthol is to stimulate the cold receptors on the skin without causing actual temperature changes. Due to its high application value, most of the are L-menthol on the market. It is widely used in cigarettes, cosmetics, toothpaste, chewing gum, sweet drinks, and medicine industry. At the same time, menthol derivatives, such as menthol lactate, menthol amides and menthol glyceraldehyde, have been widely used as substrates for the synthesis of menthol. This is because these derivatives have a stronger, longer lasting cooling effect than Menthol and are used in small amounts. So the use of L-menthol is increasing year by year. L-menthol is generally extracted from plants, and its yield is greatly affected by season, weather, planting area and so on, resulting in very large price fluctuations. Nevertheless, synthetic menthol is more and more recognized by downstream customers, especially in the synthetic field because of its stable quality, low price and stability. The development of synthetic menthol industry has a good economic prospect. The key to industrialization lies in the availability and low price of raw materials as well as breakthroughs in chiral synthesis. At present, L-menthol synthesis has been applied on a large scale in the market, but it is also worth exploring a better route and meeting the actual domestic production.
At present in China, there are few synthetic menthol enterprises with large output and advanced technology, and domestic synthetic menthol is imported from foreign companies. Therefore, the domestic synthetic menthol industry has a huge market. At the same time, there is no large-scale natural menthol cultivation base in China, so the research and development of synthetic menthol technology is more important.
