Telechelic oligomers, 4. Synthesis of telechelic oligobutadienes by rh‐catalysis

Abstract

Polymerisation of butadiene using different Rh‐compounds, specially Rh(NO3)3, in allyl alcohol results in oligobutadienes with carbonyl functionality of 1 and hydroxyl functionality between 0—1. Under proper conditions telechelics are formed. Catalysis by Rh(NO3)3 can be accelerated by the addition of alcoholate or phosphine. The oligomers have exclusively 1,4‐trans‐structure. The combined use of alcoholate and triphenylphosphine results in oligobutadienes with 40% 1,4‐cis‐, 35% 1,4‐trans‐ and 25% 1,2 structure. Determination of the structure of isolated oligomers shows that both functional groups are incorporated by insertion of a complete allyl alcohol unit. According to the frequently found endgroup CH2C(CH2OH) … the incorporation of the hydroxyl group in the termination reaction by β‐hydride transfer is most likely. The carbonyl functionality is formed in the initiation step by hydride transfer from allyl alcohol to Rh. Analogous use of allyl chloride or allyl bromide results in telechelic oligobutadienes containing two halogens per molecule. but the structure of isolated oligomers shows that only one allyl halogenide unit is incorporated. The second terminal halogen is fixed to a butadiene unit. Again the characteristic group CH2C(CH2Cl)—… is found, suggesting a termination by β‐hydride transfer.

Polymerization of a Phosphonium Diene Amphiphile in the Regular Hexagonal Phase with Retention of Mesostructure

“…To obtain more information on the structure and connectivity of 1b homopolymerized in the H I phase, the sample was examined by FT-IR spectroscopy. The sample exhibited a strong stretch at 983 cm -1 , characteristic of trans -1,4-polymerization, and showed no evidence of peaks at 735 or 910 cm -1 resulting from cis -1,4- and 1,2-polymerization, respectively . The IR spectra of a control sample of 1b photopolymerized in an isotropic aqueous phase (1 wt % amphiphile) with the same ratio of initiator also showed features indicative of solely trans -1,4-polymerization.…”