N-Acetylserotonin → Melatonin

Beteiligte Stoffe

Reaktionsschritte

To the aqueous alcoholic solution containing N-acetyl serotonine prepared in Example 2, there were added slowly and simultaneously 36 g of dimethyl sulphate and 20 g of 30% sodium hydroxide so that the pH was maintained at 12.5, while ensuring that the temperature did not exceed 40° C. During this operation, a part of the melatonine formed crystallised and this was filtered after neutralisation. The mother-liquor of crystallisation was decolourised with activated carbon, concentrated to eliminate the ethanol, then extracted with dichloromethane. After separation of the aqueous phase, the organic phase was concentrated to dryness which allowed the recuperation of a further 28 g of crude melatonine. The two fractions, which totalled 42 g, were mixed and purified by recrystallisation in a mixture containing water and ethanol in a 75:25 ratio. 30 g of white crystals of melatonine were obtained having a purity of 98.6%.

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