Nickel dioctanoate → Nickel

Participants

Reaction Steps

Hydrogenation of the epoxy-terminated polyisoprene having a theoretical average number molecular weight of about 2000 was accomplished as follows: In a flame dried flask, 7.15 grams of the oxirane functional polyisoprene was dissolved in 80 ml of cyclohexane and transferred to a dry Parr reactor under nitrogen. A nickel octanoate solution prepared by dissolving 3.0 grams of nickel octanoate in 300 ml of dry cyclohexane, 7.2 ml, (0.2 mole percent based on the number of double bonds to be hydrogenated) was charged to a separate flame dried bottle. The nickel octanoate solution was green. A 1.0 M triisobutylaluminum solution in toluene, 0.63 mls, (0.6 mole percent based on the number of double bonds to be hydrogenated) was added. Immediately, the green solution of nickel octanoate turned brown and colloidal nickel formed. The colloidal nickel was aged at about 25° C. for 15 minutes, and then transferred to the reactor containing the epoxy-terminated polyisoprene. The nitrogen was displaced by hydrogen at 50 psi of pressure and the reactor temperature was increased to 65°-70° C. with agitation. Disappearance of the double bonds was monitored by NMR, after 36 hours another catalyst addition containing 0.1 mole percent nickel was made. The reaction was allowed to proceed for another 8 hours under the same conditions, and then a final catalyst addition containing 0.1 mole percent nickel was made and the reaction was allowed to proceed for a final 8 hour time period. The epoxy-terminated hydrogenated polyisoprene product was isolated by precipitating the polymer into methanol and drying in a vacuum oven. Proton NMR analysis indicated that 97% of the double bonds were saturated without significant degradation of the epoxy groups.

Provenance & Evidence