Acetyl L-carnitine salt with a dicarboxylic organic acid and process for preparing same

A process for preparing a solid, crystalline, non-hygroscopic substance having melting point of 105° C.-110° C. which is acetyl L-carnitine acid fumarate, which comprises the following steps:

• (a) preparing a crystallization seed consisting essentially of acetyl L-carnitine acid fumarate by
• (a.1) adding equimolar amounts of acetyl L-carnitine inner salt and fumaric acid to a lower alkanol, heating and stirring the resulting reaction mixture till complete dissolution of the reagents, thus obtaining a solution;
• (a.2) cooling the solution to room temperature and adding thereto a precipitating agent in the minimum amount needed to obtain the formation of a precipitate of acetyl L-carnitine acid fumarate;
• (a.3) filtering off and drying the precipitate to be used as crystallization seed in step (c);
• (b) preparing a solution of equimolar amounts of acetyl L-carnitine inner salt and fumaric acid in a lower alkanol, heating and stirring the resulting reaction mixture till complete dissolution of the reagents and then cooling the solution to room temperature;
• (c) seeding the solution of step (b) with the minimum amount of the crystallization seed of step (a) needed to obtain a precipitate;
• (d) isolating the precipitate of step (c) by filtering it off and drying it in an oven under vacuum thus obtaining a solid, crystalline, non-hygroscopic substance comprised of acetyl L-carnitine acid fumarate, having melting point of 105° C.-110° C.

A process for preparing a solid, crystalline, non-hygroscopic substance having melting point of 105° C.-110° C. which is acetyl L-carnitine acid fumarate, which comprises the following steps:

• (i) preparing a solution of equimolar amounts of acetyl L-carnitine inner salt and fumaric acid in a lower alkanol, heating and stirring the resulting reaction mixture till complete dissolution of the reagents and then cooling the solution to room temperature;
• (ii) seeding the solution of step (i) with the minimum amount of a crystallization seed consisting essentially of acetyl L-carnitine acid fumarate needed to obtain a precipitate;
• and
• (iii) isolating the precipitate of step (ii) by filtering it off and drying it in an oven under vacuum thus obtaining a solid, crystalline, non-hygroscopic substance comprised of acetyl L-carnitine acid fumarate, having melting point of 105° C.-110° C.