The selective hydrosilylation of norbornadiene-2,5 by monohydrosiloxanes

A simple one-step approach for the selective synthesis of exo-norbornenes with organosilicon substituents is suggested through the direct hydrosilylation of norbornadiene-2,5 with chlorine-free silanes. Using the example of norbornadiene-2,5 hydrosilylation with pentamethyldisiloxane and 1,1,1,3,5,5,5-heptamethyltrisiloxane, the possibility of obtaining exo-isomers of norbornenes with 100 exo-/endo-selectivity is shown. The investigation of Pt-, Rh-, and Pd-complexes in combination with various ligands as catalysts was performed. The hydrosilylation of norbornadiene-2,5 in the presence of Pt- or Rh-catalysts was not selective and led to a mixture consisting of three isomers (exo-/endo-norbornenes and substituted nortricyclane). In the case of the Pd-salt/ligand catalytic system, the formation of an endo-isomer was not observed at all and only two isomers were formed (exo-norbornene and nortricyclane). The selectivity of exo-norbornene/nortricyclane formation strongly depended on the nature of the ligand in the Pd-catalyst. The best selectivity was revealed when R-MOP was the ligand, while the highest catalytic activity was reached with a dioxalane-containing ligand.

Microporous Materials Based on Norbornadiene-Based Cross-Linked Polymers

New microporous homopolymers were readily prepared from norbornadiene-2,5, its dimer and trimer by addition (vinyl) polymerization of the corresponding monomers with 60–98% yields. As a catalyst Pd-N-heterocyclic carbene complex or Ni(II) 2-ethylhexanoate activated with Na⁺[B(3,5-(CF₃)₂C₆H₃)₄]⁻ or methylaluminoxane was used. The synthesized polynorbornenes are cross-linked and insoluble. They are glassy and amorphous polymers. Depending on the nature of the catalyst applied, BET surface areas were in the range of 420–970 m²/g. The polymers with the highest surface area were obtained in the presence of Pd-catalysts from the trimer of norbornadiene-2,5. The total pore volume of the polymers varies from 0.39 to 0.79 cm³/g, while the true volume of micropores was 0.14–0.16 cm³/g according to t-plot. These polymers gave CO₂ uptake from 1.2 to 1.9 mmol/g at 273 K and 1 atm. The porous structure of new polymers was also studied by means of wide-angle X-ray diffraction and positron annihilation lifetime spectroscopy.

Extrathermodynamic parameters of sorption of light hydrocarbons on stationary phases prepared from tricyclononene polymers

Enthalpy and entropy of adsorption of polar and non-polar solutes were measured by chromatographic technique for new stationary phases prepared from membrane polymers based on tricyclonones. Data obtained within temperature interval from 40 to 150 °C were used to create extrathermodynamic dependences (compensation plots, dependences of enthalpy and entropy changes on solute carbon number). Compensation plots were very similar for all the stationary phases indicating similar adsorption mechanisms. The difference between the stationary phases was elucidated using dependences of enthalpy and entropy changes on solute carbon number. Higher retentivity of the stationary phase based on polymer 1 was explained by higher both enthalpy and entropy of solute adsorption on the stationary phase.