Process for the preparation of betaines
Betaines of formula R 3 N + -Q-COO − (I), wherein R is C 1-4 alkyl and Q is C 1-4 alkanediyl, optionally substituted with hydroxy, are prepared in one step by adding an ω-halocarboxylate of formula X-Q-COOR′ (II), wherein Q is as defined above, R′ is Cl 1-4 alkyl and X is chlorine, bromine or iodine, to an aqueous solution containing a tertiary amine of formula R 3 N (III), Wherein R is as defined above and a base selected from alkali hydroxides and alkaline earth hydroxides. The process is particularly suited to the production of L-carnitine.
1. A process for the production of a betaine of formula
R 3 N + -Q-COO − (I),
wherein R is C 1-4 alkyl and Q is C 1-4 alkanediyl, optionally substituted with hydroxy, by reacting, in aqueous solution, an ω-halocarboxylate of formula
X-Q-COOR′ (II),
wherein Q is as defined above, R′ is C 1-4 alkyl and X is chlorine, bromine or iodine, with a tertiary amine of formula
R 3 N (III),
wherein R is as defined above and a base selected from alkali hydroxides and alkaline earth hydroxides, characterized in that the w-halocarboxylate (II) is added to an aqueous solution comprising the tertiary amine (III) and the base.
2. The process of claim 1 , wherein the reaction is conducted at a temperature between the freezing point of the reaction mixture and +25° C.
3. The process of claim 2 , wherein the reaction is conducted a temperature of no more than +10° C.
4. The process of claim 1 , wherein the tertiary amine (III) and the base are used in an amount of 1.0 to 3 equivalents each, based on the amount of ω-halocarboxylate.
5. The process of claim 1 , wherein R is methyl.
6. The process of claim 1 , wherein Q is 2-hydroxypropane-1,3-diyl and the betaine (I) is carnitine.
7. The process of claim 6 , wherein the betaine (I) is L-carnitine.
8. The process of claim 1 , wherein X is chlorine.
9. The process of claim 1 , wherein R′ is methyl or ethyl.
10. The process of claim 1 , wherein the base is sodium hydroxide or potassium hydroxide.
11. The process of claim 1 , wherein the betaine (I) is purified by electrodialysis.