Zur Herstellung von „wasserfreier”︁ 1‐Dehydroascorbinsäure

Abstract

Die Herstellung von ,,wasserfreier" 1-Dehydroascorbinsaure (DAS) bereitete anfangs insofern Schwierigkeiten, als nach der Oxydation der Ascorbinsaure (AS) z. B. rnit Kupfer(I1)-acetatl) oder rnit p-Chinon2) beim Einengen der erhaltenen waBrigen DAS-Losungen sirupahnliche bzw. glasartige hygroskopische Maewn zuruckblieben, die sich mit Schwefelwasserstoff n u teilweise zu etwa 20-300/0 wieder in AS iiberfuhren lieBen. Es diirfte sich bei diesen wasserloslichen Produkten um ein mehr oder minder konzentriertes Hydrat der DAS gehandelt haben.Spatere Untersuchungen ergaben, da0 kristallisierte DAS aus waoriger Losung nicht darstellbar i~t~)~) , Auf Grund des hohen Schmelzpunktes und der Schwerlodichkeit in kaltem Wasser nehmen Eistert') bzw. w. Euler und Eistert5) fur die kristalline DAS im

Red pigment produced by the oxidation of L-scorbamic acid

“…The phenomenon was first reported by Koppanyi et al '(1945), who heated L-ascorbic acid (ASA) with a-amino acid in the presence of HzOz. Since then, though considerable works (Nakabayashi and Shibata, 1967;Pecherer, 1951;Ranganna and Setty, 1968;Wurtz and North, 1963) have been done on this red pigment, its exact structure and formation mechanism are still unknown.It was pointed out previously that L-scorbamic acid (SCA) might be a precursor of the red pigment (Kurata and Sakurai, 1966;Kurata et al, 1971). SCA was first prepared by Micheel and Mittag (1937) as amorphous powder which produced a red pigment on oxidation, and two possible structures, namely a chain structure and a pyrazine ring structure, were proposed for the pigment.…”

“…The phenomenon was first reported by Koppanyi et al '(1945), who heated L-ascorbic acid (ASA) with a-amino acid in the presence of HzOz. Since then, though considerable works (Nakabayashi and Shibata, 1967;Pecherer, 1951;Ranganna and Setty, 1968;Wurtz and North, 1963) have been done on this red pigment, its exact structure and formation mechanism are still unknown.…”

“…ethyl acetate: mp 165-166°( lit. 167-170°)' (El Khadem and El Ashry, 1970;Pohloudek-Fabini and Fürtig, 1959;von Euler and Hasselquist, 1952), yield ca. 38 g. Anal. Caled for C12H12N2O5: C, 54.54; H, 4.58; N, 10.60.…”

“…As the yield of SCA by the synthetic route through 2-deoxy-L-ascorbic acid (Micheel and Mittag, 1937) was not sufficient for our needs, SCA preparation through DHA mono(phenylhydrazone) produced directly from DHA was attempted. It is well known that DHA treated with phenylhydrazine hydrochloride readily produces DHA mono(phenylhydrazone), together with DHA bis(phenylhydrazone) (von Euler and Hasselquist, 1952;Pohloudek-Fabini and Fürtig, 1959), but no conclusive evidence has been given for the assignment of the position of the hydrazono group in DHA mono(phenylhydrazone). Though the most probable site is expected to be the C-2 atom, located between two carbonyl groups and susceptible to nucleophiles, the C-3 position is not completely excluded.…”

Pharmaceuticals and Related Drugs

“…A method has been developed for the determination of eyanocobalamin in amounts of 5 to 50 µg. (383). In this method the eyanocobalamin is irradiated with a mercury vapor lamp, and the liberated HCN is distilled and determined photometrically following the addition of a guaiac-copper sulfate reagent.…”