Carnitine Chloride → DL-Carnitine

Participants

Reaction Steps

A solution of DL-carnitine hydrochloride (1.0 g, 5.05 mmol) and sodium hydroxide (0.303 g, 7.58 mmol) in ethanol (15 ml) was stirred at room temperature for 2 h. The formed white precipitate (NaCl) was removed by filtration, and the solvent was evaporated under reduced pressure to give a white solid, carnitine inner salt. A suspension of the carnitine inner salt and 1-iodooctadecane (2.31 g, 6.06 mmol) in DMF-dioxane (3:5, 40 ml) was heated with an oil-bath at 120° C. under argon for 4 h. The solvent was removed under reduced pressure, and the residue was purified by a silica gel column using CH3OH—CH3Cl (v/v, 0-10%) as eluent to give the stearyl carnitine ester as a white solid. A solution of a fresh prepared stearic anhydride (1.94 g, 3.52 mmol), stearyl carnitine ester (0.953 g, 1.76 mmol) and 4-dimethylaminopyridine (0.429 g, 3.52 mmol) in CH3Cl (dry, 15 ml) was stirred at room temperature under argon for four days. The solvent was removed under reduced pressure, and the residue washed twice by cold diethyl ether. The solid was chromatographied on a silica gel column using MeOH—CHCl3 (v/v, 1:5) as eluent to give the stearyl stearoyl carnitine ester iodide. The iodide was exchanged by chloride with an anion exchange column to give the stearyl stearoyl carnitine ester chloride as a white solid. 1H NMR (300 MHz, CDCl3) δ 5.67 (q, 1H), 4.32 (d, 1H), 4.07 (m, 3H), 3.51 (s, 9H), 2.82 (t, 2H), 2.33 (t, 2 H), 1.59 (broad m, 4H), 1.25 (broad s, 58H), 0.88 (t, 6H). LSIMS (NBA): m/e 680.6 for M+ (C43H86NO4). Anal. Calcd for C43H86ClNO4.H2O: C, 70.30; H, 12.07; N, 1.91. Found: C, 70.08; H, 12.24; N, 1.75.

Provenance & Evidence