Method for preparing L-carnitine

L-carnitine is prepared by a synthesizing process starting from D-mannitol. The synthesis is started with the formation of a D-mannitol ketonide (more specifically D-mannitol acetonide from D-mannitol and acetone, whereafter the D-mannitol is split by oxydation to give glyceraldehyde acetonide, which is further reduced to glycerol acetonide. Then the free hydroxyl group is exchanged with a halogen atom (chlorine) with the formation of chlorodihydroxy propane, the primary alcoholic group of which is functionalized with the acid chloride of a sulfonic acid (tosylchloride). The reaction of the tosyl derivative with the salt of hydrogen cyanide leads to the formation of the corresponding nitrile which, when reacted with trimethylamine gives carnitinonitrile. The nitrile group is now hydrolyzed to give L-carnitine chloride. The formation of L-carnitine can then be obtained by exchanging the chloride ion with a hydroxyl ion.