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The preparation of Na4Mn14O27, 9H2O (hitherto named manganomanganite or δ‐MnO2) by oxidation of a fresh Mn(OH)2 suspension in aqueous NaOH by molecular oxygen, and its probable structure are described. It is a double layer manganate (IV) structure resembling other manganates such as chalcophanite. Orthorhombic unit cell parameters are, a0 = 8,54, b0 = 15,39, c0 = 14,26 Å. In diluted nitric acid topotactical transition to manganese (III) manganate (IV), Mn7O13.5H2O (unit cell: a0 = 2,84, c0 = 7,27 Å; primitively hexagonal), and by prolonged digestion to nsutite, γ‐MnO2, occurs.

Abstract

Sociktk suisse de chimie, Bile -Societk svizzera di chimica, Basilea Nachdruck verboten -Tous droits rkserv6s -Printed by Birlrhauser AG., Basel Summary. The preparation and probable structure of manganese (111)-manganate (IV)Mn,0,,,5H20 (a, = 2,84, co = 7,27 A) and manganous(I1)-manganate(1V) Mn70,,,6H,0 are described. Both consist of platelets. Digesting in diluted HNO, leads to y-MnO, (nsutite). Manganese (111)-manganate (IV) is much less stable than the sodiummanganese (11, 111)-manganate-(IV) described earlier and looses water easily when heated or in vacuo. Water loss results in breaking down of the double layer lattice, and the product is only two-dimensionally ordered, producing only prism reflections on the X ray diagramm. Heating results in a continuous transition to the two-dimensionally ordered phase, then to a finely divided and very disordered y-MnO,, and eventually to a finely divided and disordered B-MnO, (pyrolusite). The transition is topotactical so far, but further heating produces cr-Mn,O, without obvious topotactical relations to the earlier products. The so-called '6-Mn0,' (birnessite) appears to be a family of finely divided and very disordered varieties of such manganates(1V) with part of the Mn3+ substituted by Mn4+. Since such products usually contain remarkable amounts of alkali ions, they are rather varieties of the earlier described sodiummanganese (11, 111)-manganate (IV). A provisional explanation of the streaking in the electron diffractions of these manganates (IV) is given. With respect to these results the socalled ' 8-MnO,' can no longer be attributed t o the true manganese dioxides.

BRENET und Mitarbeiterl) haben wohl als erste darauf hingewiesen, dass bei der Entladung von LECLANCHk-Zelkn y-MnO, seine Struktur zunachst nicht andert und dass im ersten Stadium der elektrolytischen Reduktion nur eine Gitterdehnung eintritt ,).Wir haben festgestellt, dass auch bei der chemischen Reduktion von y-MnO,, z. B. mit Hydrazin, zunachst nur eine Dehnung des Gitters stattfindet. Bis jetzt haben wir nur die stark fehlgeordnete Varietat von y-MnO, untersucht, wie sie bei elektrolytischer3) Herstellung und nach der Vorschrift von GLEMSER 4, aus Mangansulfat, Salpetersaure und Ammoniumpersulfat entsteht.Diese Varietat von y-MnO, gibt ein RONTGEN-Diagramm mit nur 5 Reflexen, sehr ahnlich dem Diagramm von 6-FeOOH5). Zwischen dieser stark fehlgeordneten Varietat von y-MnO, und Ramsdell it, einem seltenen MnO,-Mineral, scheint eine

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.

The hydration of different forms of magnesium oxide by water vapour was studied at room temperature using gravimetric, X‐ray and electron microscopic methods. It takes place in four steps; formation of a layer of chemi‐ and physisorbed water, transition of magnesium and hydroxide ions in the layer of physisorbed water, nucleation of the hydroxide and growth of the hydroxide crystals.

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