DL-CARNITINE

Originator

Flatistine,Sauba,France,1978

Uses

antihyperlipoproteinemic, gastric/ pancreatic secretion stimulant

Definition

ChEBI: Carnitine is an amino-acid betaine that is butanoate substituted with a hydroxy group at position C-3 and a trimethylammonium group at C-4. It has a role as a human metabolite and a mouse metabolite. It is functionally related to a butyrate. It is a conjugate base of a carnitinium.

Manufacturing Process

9.3 g of epichlorohydrin was added at a temperature of 40°-50°C under stirring to 9.6 g of trimethylamine hydrochloride dissolved in 10 cc of water. Continuing the reaction for an hour at the above temperature, the reaction product was concentrated under reduced pressure to obtain the crystals of 3- chloro-2-oxypropyl trimethyl ammonium chloride which were recrystallized with 25 cc of ethanol. The crystals obtained by concentrating the mother liquor were also recrystallized. The yield was 17.4 g (MP 190°C, yield 91.5%). This substance occurs as white, somewhat hygroscopic crystals and is readily soluble in water or alcohol, but insoluble in benzene, toluene, ether, acetone or chloroform.
The result of analysis assuming (C6H15C10N)+Cl--calculated value: N, 7.45%; total Cl, 37.7%; Cl-, 18.88%. Observed value: N, 7.36%; total Cl, 37.54%; Cl-, 18.98%.
18.8 g of 3-chloro-2-oxypropyl trimethyl ammonium chloride was dissolved in a mixed solvent composed of 19 cc of methanol and 1 cc of water. 5.1 g of sodium cyanide dissolved in 8 cc of water was dropped into the solution at 50°C under stirring. After dropping, the mixture was held at this temperature for 30 minutes under stirring. The reaction product was then neutralized with 6 N hydrochloric acid toward pH 5, and, after cooling, sodium chloride separated out and was filtered. The filtrate was concentrated to dryness under reduced pressure, and the residue was washed with small quantity of ethanol. Drying the residue, dissolving in hot methanol, filtering off insoluble matters, and cooling mother liquor, the crystals of 3-cyano-2-axypropyl trimethyl ammonium chloride which deposited out were filtered and dried. Yield 16.7 g [MP (decomposition) 220°-223°C, yield 93.4%].
12.5 cc of concentrated hydrochloric acid was added to 17.9 g of 3-cyano-2- oxypropyl trimethyl ammonium chloride. Gradually heating the mixture on a water bath under stirring, so bringing the temperature up to 98°C at the end of about 3 hours, 9 cc of water was added. After cooling, free hydrochloric acid was neutralized with 3 cc of 6 N sodium hydroxide, and then by adding 1 g of active charcoal, the reaction product was decolorized and filtered. The filtrate was concentrated to almost dryness under reduced pressure. Then, this concentrate was, after washing with 10 cc of ethanol, dried. Yield 24.7 g.
The dried product was dissolved in 46.5 cc of glacial acetic acid by heating on a boiling water bath. The insoluble matter is removed by filtering hot, and on cooling the mother liquor, crystals of carnitine hydrochloride separated out. The crystals were filtered, washed with 10 cc of ethanol, and dried. Recrystallizing 19.7 g of the crude carnitine with methanol, 17 g of the refined carnitine was obtained [MP 195°-198°C (decomposing point), yield 86%], The overall yield of the refined carnitine through whole steps was about 74%. Carnitine thus prepared was an odorless, white, crystalline powder, having a strong acid taste.

Therapeutic Function

Gastric stimulator, Pancreatic stimulator

Purification Methods

The S(L) isomer is levocarnitine, Vitamin B7. The R or S isomers crystallise from EtOH/Me2CO (hygroscopic). The R or S hydrochlorides crystallise from hot EtOH or EtOH/Et2O and have m 142o(dec). The RS-isomer crystallises from hot EtOH (hygroscopic). The RS hydrochloride crystallises in needles from hot EtOH and has m 196o(dec). [(±) Mazzetti & Lemmon J Org Chem 22 228 1957, Beilstein 4 H 513, 4 I 548, 4 II 937-8, 4 III 1632-5, 4 IV 3185.]