L-Menthol CAS 2216-51-5

The route of Germany’s Dezhixin Firm is received Plan 4, which is currently the world’s biggest menthol synthesis method. The advantage of this path is that the synthesis steps are reasonably simple, however the disadvantage is that the splitting up and recuperation process is difficult. First, m-cresol and propylene are utilized in Lewis Thymol 9 was acquired in 63% return under acid catalysis [16], and afterwards the benzene ring was hydrogenated under the catalysis of a nickel/iron/chromium/ aluminum alloy to acquire various stereoisomer mixes of menthol 6. This action The return is 99.5%, which has 60.3% of the mixture of L-Menthol (1R, 3R, 4S)-6 and d-menthol (1ST, SIX, 4R)-6, and 39.2% of other stereoisomers. (1R, Mixtures of 3R,4 S)-6 and (1ST,3 S,4 R)-6 and various other stereoisomers can be divided by distillation. (1R,3 R,4 S)-6 and (1S,3 S,4 R)-6 After esterification with benzoic acid, (1R,3 R,4 S)-10 and (1S,3 S,4 R)-10 were acquired specifically, and afterwards optically pure menthyl benzoate was utilized for seeding and crystallization, and after that the high-purity (1R, 3R,4 S)-10 and (1ST,3 S,4 R)-10. Finally, the separated esters are just hydrolyzed to obtain high-purity L-menthol and D-menthol. Except for the product L-menthol, all other After recouping the configured menthol, it can be catalytically dehydrogenated once more to acquire thymol 9, and after that hydrogenated and separated. The total return of this route can surpass 90%. For the splitting up action, Dezhixin Business in 2002 Lipase splitting up modern technology was created. As an example, using lipase drawn out from Yeast for splitting up, the acquired L-Menthol ee value can be virtually 100%, however the cost is too high and has not been industrialized.