method for producing salts of l-ascorbic acid - 2 - sulfats, corresponding salts of sodium and calcium, and on the basis of poultry feed

摘要

For the preparation of mono- or di-alkali metal salts or alkaline earth metal salts of L-ascorbic acid-2-sulphate, L-ascorbic acid is first protected with a ketone or an aldehyde in the 5- and 6-positions. The resulting product is then sulphated in dimethylformamide using a sulphating agent. The sulphating agent used is either sulphur trioxide, alkali metal chlorosulphonate or sulphuryl chloride, or chlorosulphonic acid in the presence of pyridine or urea. The reaction mixture is then neutralised with an alkali metal hydroxide or an alkaline earth metal hydroxide and the protective group is removed. High yields are achieved in this procedure. The mono- or di-alkali metal salts and alkaline earth metal salts of L-ascorbic acid-2-sulphate can be used as a poultry feed additive. They lead to an improvement in the strength and thickness of the eggshells.