GB766178A - Novel betaine salts and method for producing same - Google Patents

Abstract

The invention comprises a betaine citrate, e.g. monobetaine citrate, and the preparation thereof by reacting betaine hydrate, or a betaine salt other than a citric acid salt, and citric acid, or a salt thereof other than a betaine salt, in a solvent wherein at least one of the reagents is soluble and wherein betaine citrate, when the sole salt reaction product, is either soluble or insoluble, or one of two reaction products, namely betaine citrate and a by-product salt, is insoluble while the other is soluble. The reagents may be used approximately in the ratio of molecular proportions present in the desired betaine citrate, e.g. in equimolecular proportions to form a monobetaine citrate. The betaine hydrate for use in the above process may be prepared by the reaction of a betaine salt of an inorganic acid, e.g. the chloride, bromide or sulphate salt, with a mineral base, e.g. sodium, potassium or barium hydroxide, in alcoholic solution, e.g. a lower alkyl alcohol such as methanol and ethanol. The above process may be modified in that the betaine citrate is prepared by double decomposition of a salt of betaine with an organic or inorganic acid (other than citric acid) and a mineral or organic base salt of citric acid (other than the betaine salt) in a solvent in which one of said salts and the betaine citrate produced are soluble and in which the by-product salt produced is insoluble, or in which the betaine citrate is insoluble and the by-product salt is soluble. Thus in the double decomposition process the betaine salt reactant may be betaine chloride, bromide, sulphate or phosphate and the citric salt reactant may be barium citrate. In a preferred process, betaine sulphate is reacted with barium citrate and the temperature of the reaction products is raised to that at which the barium sulphate formed precipitates quantitatively, e.g. in water, methanol, or dilute aqueous ethyl alcohol as the reaction solvent. After filtering off the precipitated by-product salt in the double decomposition process and concentrating, crystallization of the betaine citrate may be effected with the addition of another solvent for the betaine citrate or more of the same solvent, suitable solvents being ethyl alcohol or acetone. Two detailed examples are given.