H e r s t e l l u n g v o n 3,7-Dimethyl-octanon-(2) a u s 2 , 6 -D i m e t h y l -o n a n t hsiiure. 2,022 g 2,6-Dimethyl-onanthsiiure wurden mit 2 g Thionylchlorid in 20 om3 ab- It is shown that the isomeric alcohols euphol and lanosterol differ only in the configuration of carbon atoms 13, 14 and 17. In all further structural and steric details the two alcohols are identical.
δ‐MnO2 shows a fast isotope exchange reaction owing to its special structure. It consists of an irregular accumulation of thin MnO2‐layers. Surface determinations were carried out by the BET adsorption method. The isotherms were measured with nitrogen at the temperature of liquid nitrogen. The surface found for MNII‐Manganite samples was between 30 and 50 m2/g. For δ‐MnO2 samples the surface was about 300 m2/g. The calculated surface area for a monoatomic layer amounts to 720 m2/g. Therefore the thicknes of the “two‐dimensional” δ‐MnO2‐crystals lies between 2 to 3 atomic layers.
The spectrophotometric method is shown to be very effective in the examination of acid chlorite solutions, inasmuch as among the ionic and molecular species which come into consideration – ClO2, ClO2′, HClO2, ClO3′ and Cl′ – the first three demonstrate characteristic absorption spectra which are suitable to detect and quantitatively determine these compounds.
The log ε‐curves for ClO2, ClO2′, HClO2 and ClO3′ are communicated in the wave lenght region of 2200–4800 Å. ClO2, ClO2′ and HClO2 can be simultaneously determined by use of wave partners of equal extinction for ClO2.
The speed of formation of ClO2 in dilute chlorite solution is not a simple function of the pH. In the pH region from 2 to 4, the ratio of ClO2′ consumed to ClO2 formed to H· consumed was found to be equal to 2 : 1 : 1, corresponding to the reaction equation
At pH values less than 2, the amount of ClO2 formed is less in reference to the ClO2′ consumed.
The total solubility of amorphous FeIII‐hydroxide and α‐FeOOH in 3M NaClO4 has been determined using 59Fe as tracer. The solubility determination of the amorphous hydroxide extended over the pH‐range 3–14. At pH < 3.5 the results agree satisfactorily with the value calculated using the solubility‐product and the constants of hydrolysis. At pH 5–12 an average solubility of ∼ 10−7 M has been measured but the results show considerable fluctuations. Therefore a colloidal solubility has been assumed. In the alkaline range pH > 12 it could be shown that the equilibrium Fe(OH)3 + OH−⇆Fe(OH) 4− is established, the following pKS4 being found to be after 2 h ageing 4.50 ± 0.15 and after 96 h ageing 5.00 ± 0.15.
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