Katsuhiko Kishi

Synthesis and photochemical properties of insoluble poly(styrene) beads containing pendant norbornadiene moieties

Abstract Insoluble polymer beads bearing pendant norbornadiene (NBD) moieties were synthesized by the substitution reaction of insoluble chloromethylated poly(styrene) beads with potassium salts of certain NBD derivatives having carboxylic acid or phenol groups using a phase transfer catalyst. The reaction proceeded smoothly in high conversions in DMF at 90°C for 72 h to give the corresponding insoluble polymer beads bearing NBD moieties. Rates of photochemical reaction of the obtained insoluble polymer beads were measured by IR spectrometry using KBr disk plates. The photochemical valence isomerization from 3-phehyl-2,5-NBD-2-carboxylate (PNCA) moiety to the corresponding quadricyclane (QC) group and catalytic reversion from QC to the NBD moiety were also examined in dichloromethane, and it was found that the photochemical valence isomerization and the catalytic reversion in insoluble polymer beads can be recycled in high conversions at last for 10 runs.

Development and application of latent hydrosilylation catalysts [2]—Control of catalytic activity of platinum catalyst by polystyrene derivatives having propargyl moieties

A new thermal latent hydrosilylation catalyst on the basis of H2PtCl6 and polystyrene derivatives having propargyl moieties is described. The polystyrene derivatives having various propargyl moieties were obtained by the reaction of propargyl alcohols with poly(p-chloromethylstyrene) or its copolymer with styrene. The polymer-supported platinum catalysts were prepared by aging H2PtCl6 with these polymers in tetrahydrofuran at 30 °C for 12 h. In the presence of the polymers, the hydrosilylation activity of H2PtCl6 was found to be controlled thermally in the model reaction of trimethylsilane and triethylvinylsilane. Effective control of the crosslinking reaction of silicone resin was also achieved by using these latent catalyst systems.

Development and application of a latent hydrosilylation catalyst. IX. Control of the catalytic activity of a platinum catalyst by polymers bearing amine moieties

A new thermal-latent hydrosilylation catalyst consisting of H 2 PtCl 6 and polymers bearing amine moieties is described. In the presence of aminated polymers, the catalytic activity of H 2 PtCl 6 was suppressed remarkably in the model reaction of triethylsilane with trimethylvinylsilane, whose effect was remarkably higher in comparison with monomeric amines. On heating, however, sufficient catalytic activity was attained where the activation temperature was dependent on the amine content in the polymer and polymer structure. Furthermore, this catalyst system was applied to the curing process of silicone resin to confirm the thermal-latent character of the catalyst.

Development and application of latent hydrosilylation catalyst [6]: control of activity of platinum catalyst by isocyanide derivatives on the crosslinking of silicone resin via hydrosilylation

Abstract Quite effective nature of isocyanides to control the curing reaction of silicone resin via the Pt-catalyzed hydrosilylation process is described. In the presence of the isocuanides, the curing reaction of the silicone resin by H2PtCl6 did not occur at ambient temperature, while the lack of the isocyanide systems conducts the smooth curing, indicating that the present systems serve as a thermal latent catalyst for silicone resin. The curing temperature was controllable by the character and the concentration of the isocyanides employed.

Development and application of latent hydrosilylation catalysts.: 3. Control of activity of platinum catalysts by poly(vinyl ether) having propargyl moieties

Abstract A flexible polymer having propargyl moieties ( 2 ) was prepared by the cationic polymerization of vinyl monomer ( 1 ) derived from 4-hydroxybutyl vinyl ether and propargyl bromide. In the presence of the polymer, the catalytic activity of H 2 PtCl 6 towards the hydrosilylation of triethylsilane and trimethylvinylsilane was found to be retarded effectively at ambient temperature, but not on heating. Compared to the monomeric propargyl derivatives, the polymeric system was quite effective in controlling the catalytic activity. Under the same concentration of acetylene moieties and H 2 PtCl 6 , the initiating temperature of the present system was ca. 50°C higher than for the catalyst composed of the monomeric propargyl derivatives, but was ca. 20°C lower than for that consisting of the propargylated polystyrene derivative that the authors have reported recently. Effective control of the crosslinking reaction of silicone resin was also achieved using the present latent system.