between methylenation (i) with subsequent cyclopropanation (jj), to give the rotanes ( I ) with ii=ri1+4, or cyclopropylidenation (iii). in order to repeat the homologation sequence.Starting from 7-cyclopropylidenedispiro[2.0.2.I]heptane ( 2 ) , rii=O"l', we have not only devised a coni,enient preparation of the key compounds ( 5 ) . J H = O and m=I. for the known syntheses of [4]rotane ( I h)l'"l and [Slrotane ( I c )~'~! , but also accomplished the first preparation of [6]rotane ( I 1 1 ) Received: September 13. 1976 [Z 558 IE] German version: Angew. Chem. XX. 807 (1976) CAS Registry numbers: ( 1 J. 60788-82-I [l] J . Wuiss, Fortschr. Chem. Forsch. 5, 635 (1966); K . J . W~m r and W L. J d / x . Inorg. Chem. 6, 107 (lY67).
Polypyrrole is a promising positive electrode material for the application in secondary lithium cells. The elemental analysis performed on electrochemically prepared polypyrrole films indicates a specific capacity of 82 Ah/kg. This specific capacity can be cycled in half cell experiments for many hundred times. The rate of self discharge of such an electrode is about 1%/day. On the basis of these results it will be shown that a lithium polypyrrole cell of optimal design may arrive at an energy density of about 40 ‐ 60 Wh/kg. First results obtained with practical cells of technical design confirm this statement.
Orientation of molecular dipoles in poly(vinylidene fluoride) (PVF2) films under electric field has been measured by ir spectroscopy using ir transparent indium-tin-oxide electrodes. Significant changes in ir transmission with electric field have been observed at 512 and 446 cm−1, which demonstrate that crystalline dipoles in β-phase PVF2 orient along the electric field. As the field is cycled between positive and negative values, the dipole orientation exhibits a hysteresislike behavior, demonstrating that the polarization of β-phase PVF2 and its switching result directly from the orientation of crystalline dipoles. Time response of dipole orientation shows that the total orientation consists of an instantaneous part and a slowly developing part. Only the latter seems to contribute to the remnant polarization and its switching.
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