Isolation and properties of the ferrioxamines A, B, C, D1, D2, E and F, iron containing growth factors belonging to the group of the sideramines, are described.

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950HELVETICA CHIMICA ACTA.Ihre KH/KD-Werte liegen z. B. beim Benzaldehyd unterhalb p H 10 zwischen 6,4-7,l und oberhalb pH 11 zwischen 2,7 und 3,O.In The oxidation of formate (HCOO-and DCOO-) with permanganate in alcaline solution has been investigated at lo and 20° C. For the determination fltamm's procedure has been used, modified to a semimicromethod, suitable for the determination of 5 -100 pMols of formate.A comparison of the rate of oxidation rcvealed a considerable isotopic effect; the ratio of the rate constants KH/KD amounting to 6-10.I n mixtures of HCOO-and DCOO-there is an approximately linear relationship between DCOO-content and the relative amount of oxidized formate. This behaviour can be used for a rough estimate of the DCOO-content.Medizinisch-Chemisches Institut und Institut fiir anorg., analyt. und physikal.