Process for the preparation of riboflavin
AssigneeMerck Patent GmbH
InventorsRudolf Wolf, Fritz Reiff, Rolf Wittmann, Jurgen Butzke
Life of this patent
Estimating the term…
Abstract
A process is provided for preparing riboflavin from D-glucose in good yield and under efficient conditions.
Claims27
A process for preparing riboflavin from D-glucose, comprising the steps of:
- (a) oxidizing D-glucose to D-gluconic acid or an alkali metal gluconate;
- (b) oxidizing the resultant D-gluconic acid or gluconate to D-arabinose with hypochlorite;
- (c) epimerizing the resultant D-arabinose to obtain substantially an equilibrium epimer mixture containing D-ribose, and coarsely separating at least 80% of the D-arabinose therefrom;
- (d) directly catalytically hydrogenating the resultant D-ribose-rich epimer mixture in the presence of 4-nitro-1,2-xylene or 3,4-xylidine, and directly crystallizing substantially pure N-D-ribityl-3,4-xylidine from the resultant hydrogenation mixture;
- (e) coupling the resultant N-D-ribityl-3,4-xylidene with a benzenediazonium salt to form 1-D-ribitylamino-3,4-dimethyl-6-phenylazobenzene;
- and
- (f) reacting the resultant 1-D-ribitylamino-3,4-dimethyl-6-phenylazobenzene with barbituric acid to form riboflavin.
A process for oxidizing D-gluconic acid to D-arabinose, comprising the step of rapidly adding to a 10-40% by weight aqueous solution of D-gluconic acid at pH 4-6, at a temperature of 30.degree.-90.degree. C., an approximately 10 to 20% by weight hypochlorite solution.
A process for the preparation of N-D-ribityl-3,4-xylidine, wherein D-arabinose is epimerized with a molybdenum (VI) compound to give an epimer mixture containing D-ribose and D-arabinose, at least 80% of the D-arabinose is then separated from the epimer mixture and recovered, the remaining epimer mixture is directly catalytically hydrogenated in the presence of 4-nitro-1,2-xylene or 3,4-xylidine, and the resultant N-D-ribityl-3,4-xylidine is directly recovered by crystallization.
Dependencies are inferred from the claim text.