Highly fluorinated liquid crystals with unprecedented polarity were obtained by introducing a tetrahydropyran moiety into their mesogenic core structure. The new materials exhibit an unusually favourable combination of mesophase properties, excellent solubility and low rotational viscosity,

Max-Plank-lnstitut fur Strahlenchemie, Stiftstrasse 34-36, 0-4330 Mulheim a.d. Ruhr 7, Federal Republic of Germany U.V. irradiation (medium-pressure Hg lamp) induces reaction of TsiSiPh,l (1 a) [Tsi = (Me,Si),C]with methanol to give both the unrearranged and rearranged methoxides TsiSiPh,OMe and ( Me,Si),C-(SiPh,Me) (SiMe20Me) ; in the presence of LiN0, some (Me3Si),C(SiPh2Me) ( SiMe20N02) is also formed. The analogous solvolysis in PhNH2 gives the rearranged anilide ( Me3Si),C(SiPh2Me) (SiMe2-NHPh). These reactions are thought t o involve the intermediate formation of a silico-cation. On the other hand the exclusive formation of the unrearranged chloride TsiSiPh,CI upon irradiation in CCI4 appears t o involve a free-radical process. The photoinduced rearrangement of (1 a) to ( Me3Si),C(SiPh2Me) (SiMe,l) in n-&HI,, n-C6H,,, Et,O, and PhOMe may involve a cationic intermediate, but a free radical rearrangement cannot be ruled out; the subsequent formation of a disilaindane derivative (6) in PhOMe probably involves cyclization of a free radical. The iodide TsiSiPhMel also undergoes rearrangement to (Me,Si),-C(SiPhMe,) (SiMe,l) upon irradiation in n-C5H1 , . The methanolysis of TsiSiMe,l is also photo-catalysed, though less effectively than that of (la).

No abstract

Durch Belichtung des Silyliodids (I) in Methanol erhält man ein Gemisch der Silylmethylether (II) und (III).

Die Bestrahlung der Organosiliciumverbindung (I) in MeOH liefert sowohl unumgelagertes als auch umgelagertes Methoxid (II) bzw. (III) und in Gegenwart von LiNOa auch (IV).