Starting from 2,4,6-triiodophenol, 2,3,5-triiodobenzoic acid and 3,5-bis(acetylamino)-2,4,6-triiodobenzoic acid, polymerizable methacrylates were synthesized and characterized by elemental analyses, IR, 'H-NMR and I3C-NMR spectroscopy. The iodine-containing methacrylates show a different radical polymerization behaviour. 2,4,6-Triiodophenyl methacrylate gives only oligomeric products in the presence of azoisobutyronitrile (AIBN), whereas 2-methacryloyloxyethyl 2,3,5-triiodobenzoate yields polymers. On the basis of mixtures of isomeric 1,3-dimethacryloyloxy-2-and 1,2-dimethacryloyloxy-3-(2,3,5-triiodobenzoyloxy)propane with usual crosslinking monomers, radiopaque materials were prepared. ZUSAMMENFASSUNG:Ausgehend von 2,4,6-Triiodphenol, 2,3,5-Triiodbenzoesaure und 3,5-Bis(acetylamino)-2,4,6-triiodbenzoesaure wurden polymerisationsfahige Methacrylsaurederivate synthetisiert und mittels IR-, IH-NMR und '3C-NMR-Spektroskopie sowie Elementaranalyse charakterisiert. Die iodhaltigen Methacrylate zeigen eine unterschiedliche radikalische Polymerisationsneigung. Wahrend 2,4,6-Triiodphenylmethacrylat in Gegenwart von AIBN nur oligomerisiert, werden aus 2-Methacryloyloxyethyl-2,3,5-triiodbenzoat Polyrnere erhalten. Auf der Basis von Mischungen eines Isomerengemisches aus 1,3-Dimethacryloyloxy-2-bzw. 1,2-Dimethacryloyloxy-3-(2,3,5-triiodben-zoy1oxy)-propan und gebrauchlichen Vernetzermonomeren wurden rdntgenopake Materialien hergestellt.

SummaryFrom treatment of D-labelled 1,2exo-, 1,2endo-and 2endo,6endo-trimethylenenorbornane (1, 2 and 3, resp.) with aluminum bromide in carbon disulfide, the evidence is gained that a degenerate rearrangement is involved in the adamantane rearrangement of both 1 and 2 to 3.

New multifunctional urethane methacrylates were synthesised by addition of methacrylates containing a hydroxy group, such as 2‐hydroxyethyl methacrylate, 2‐hydroxypropyl methacrylate or glycerol dimethacrylate, to α,α,α′,α′‐tetramethyl‐m‐xylylene diisocyanate. The structure of the new monomers was confirmed by IR, 1H NMR and 13C NMR spectroscopy. The photopolymerisation of the crosslinking monomers in bulk using camphorquinone as photoinitiator results in transparent, crosslinked polymers.

SUMMARY: New multifunctional urethane methacrylates were synthesised by addition of methacrylates containing a hydroxy group, such as 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate or glycerol dimethacrylate, to a,a,a9,a9-tetramethyl-m-xylylene diisocyanate. The structure of the new monomers was confirmed by IR, 1 H NMR and 13 C NMR spectroscopy. The photopolymerisation of the crosslinking monomers in bulk using camphorquinone as photoinitiator results in transparent, crosslinked polymers.ZUSAMMENFASSUNG: Neue multifunktionelle Urethanmethacrylate wurden durch Addition von hydroxygruppenhaltigen Methacrylaten, wie 2-Hydroxyethylmethacrylat, 2-Hydroxypropylmethacrylat oder Glycerindimethacrylat, an a,a,a9,a9-Tetramethyl-m-xylylendiisocyanat hergestellt. Die Struktur der neuen Monomeren konnte durch IR-, 1 H NMR-und 13 C NMR-Spektroskopie bestätigt werden. Die Photopolymerisation der Vernetzermonomeren in Substanz führte mit Campherchinon als Photoinitiator zu transparenten Polymernetzwerken.

Summary1,2endo-Trimethylenenorbornane (1) in the presence of aluminium bromide in carbon disulfide at -60" isomerizes at a much higher rate than its 2exo-isomer 2 to 2endo,6endo-trimethylenenorbornane (3) as the sole product. By consequence, the hydrocarbon 2 being the next intermediate in the sequence of the adamantane rearrangement of 1 seems to be very unlikely.In 1968 Whitlock & Siejlcen [l] described a map of interconversions of tricyclodecanes that contain all 10 carbon atoms within rings (no alkyl groups) and no three-and four-membered rings. Including stereoisomers, the 'adamantaneland' is composed of a set of 19 isomeric C10H16 hydrocarbons. On the basis of molecular mechanics (empirical force field calculations) on these tricyclodecanes and presumed cationic intermediates, Schleyer et al. [2] made predictions of the most likely pathways') leading from each isomer to adamantane. For the rearrangement of 1,2endo-trimethylenenorbornane (1)2) its stereoisomer 1,2exo-trimethylenenorbornane (2)3) was proposed as the next intermediate in the sequence.