Research ArticleORGANIC CHEMISTRY

Heteroatom-assisted olefin polymerization by rare-earth metal catalysts

See allHide authors and affiliations

Science Advances  21 Jul 2017:
Vol. 3, no. 7, e1701011
DOI: 10.1126/sciadv.1701011
  • Fig. 1 Possible influences of a heteroatom in the transition metal–catalyzed copolymerization of ethylene with an FG-containing α-olefin.

    (A) A heteroatom (FG) acts as a poison to deactivate the catalyst and hamper the polymerization. [M], transition metal. (B) FG acts as a spectator that is compatible with the catalyst. (C) FG acts as a promoter to enhance the polymerization activity of the α-olefin monomer and facilitate its incorporation into polyethylene through the heteroatom-assisted catalyst-olefin interaction. This HOP could serve as a useful strategy for polar-nonpolar olefin copolymerization, as demonstrated in this work.

  • Fig. 2 Catalysts and monomers investigated in this study.

    (A) Rare-earth complexes used as precatalysts in this work. (B) Heteroatom-containing α-olefins examined in this work.

  • Fig. 3 Computational analysis of the polymerization of 1i by the cationic species Cat generated in the reaction of Sc-3 with [Ph3C][B(C6F5)4].

    (A) DFT-calculated energy profile of the polymerization of 1i by Cat. (B) Structures of the stationary points shown in the energy profile. The less favored pathway is pale-colored. R = CH2C6H4NMe2-o; TS, transition state; ΔGsol, relative Gibbs free energy in solution.

  • Table 1 Polymerization of heteroatom-containing α-olefins.

    Conditions: [M] (0.03 mmol), [Ph3C][B(C6F5)4] (0.03 mmol), 1 (1.5 M), toluene, room temperature (rt), 24 hours (unless otherwise noted). n.o., not observed; n.d., not determined.


    Embedded Image
    EntryMonomer 1[M]1/[M]Polymer 2Yield (%)*Mn (×103)Mw/Mnrrrr (%)Tg (°C)§
    11aSc-1100/12a0ǁ
    21bSc-1200/12b9833.61.77>959
    31bSc-2200/12b0
    41bSc-3200/12b10029.81.33>955
    51bSc-3500/12b7859.81.78>954
    61cSc-3100/12c0
    71dSc-3500/12d9380.42.06>95−32
    81eSc-3500/12e7183.61.96>95−31
    91fSc-3500/12f8974.51.76>95n.o.
    101gSc-3500/12g9580.41.85>9598
    111hSc-3100/12hTrace
    121hSc-4100/12h9930.21.16>95n.o.
    131iSc-3200/12i10057.02.23>950
    141iSc-31000/12i100103.22.29>950
    151iSc-32000/12i100133.12.20>95−1
    161iSc-35000/12i63189.02.03>950
    17#1iSc-3200/12i100304.91.65>950
    18#1iSc-32000/12i93585.51.57>951
    191jSc-31000/12j10083.42.36>95−1
    201kSc-31000/12k97103.52.02>9512
    211lSc-31000/12l99132.92.52>95−5
    221mSc-31000/12m100118.42.87>952
    231nSc-31000/12n9920.72.68>9529
    24**1nSc-31000/12n9960.22.45>9524
    251oSc-31000/12o100102.01.80>95n.o.
    261pSc-31000/12p100123.81.84>95−8
    271qSc-3500/12q10058.92.5592−7
    281rSc-3500/12r104.11.56n.d.−2
    291rSc-1500/12r10014.61.77n.d.27
    301sSc-3100/12s371.51.39n.d.2
    311sSc-1100/12s391.21.46n.d.22
    321sSc-4100/12s643.11.53n.d.36
    331tSc-1100/12tTrace
    341tY-1100/12t236.81.5788−5
    351uSc-3200/12u4011.31.9989−21
    361uSc-1200/12u808.92.1690−23
    371uSc-4200/12u8823.52.36>95−22

    *Weight of polymer obtained/weight of monomer used.

    †Determined by gel permeation chromatography (GPC) in tetrahydrofuran (THF) at room temperature against polystyrene standard.

    ‡Determined by 13C nuclear magnetic resonance (NMR) analysis.

    §Determined by differential scanning calorimetry.

    ǁFormation of 1-phenoxy-1-propene (an isomerization product of 1a) was observed.

    ¶Determined by high-temperature GPC in 1,2-dichlorobenzene at 145°C against polystyrene standard.

    #−40°C.

    **0°C.

    • Table 2 Copolymerization of heteroatom-containing α-olefins with ethylene.

      Conditions: [Sc] (0.03 mmol), [Ph3C][B(C6F5)4] (0.03 mmol), monomer 1, ethylene (1 atm), toluene (50 ml) at 20°C for t hours (unless otherwise stated).


      Embedded Image
      Entry1[Sc]1/[Sc]t (hour)3Yield
      (g)
      Activity*Mn
      (×103)
      Mw/Mni.r.
      (%)
      Tg
      (°C)§
      Tm
      (°C)§
      11i, FG = SPhSc-3100/11.53i0.122.714.71.7673.5−8n.o.
      21iSc-5100/123i0.6410.620.61.3929.0−36125
      31iSc-5500/1203i1.953.357.71.9244.9−16128
      41iSc-6100/153i1.117.482.41.692.6−18124
      51iSc-6500/1203i3.485.831.71.9615.7−19119
      61iSc-61000/1203i4.397.317.02.3838.9−14110
      71r, FG = PPh2Sc-5100/10.333r1.03103.254.02.209.52133
      81rSc-5500/11.53r2.9064.4ǁǁ32.510124
      91b, FG = OPhSc-5100/153b0
      101t, FG = CH2OPhSc-5100/10.53t1.3690.4124.92.298.7-40127
      111tSc-5500/153t3.0720.589.61.9524.8−39114
      121tSc-6100/153t1.7811.8154.22.713.3−31124
      131tSc-6500/1203t1.222.083.02.2311.8−36119

      *103 g of copolymer per mole of Sc per hour per standard pressure of ethylene.

      †Determined by GPC in 1,2-dichlorobenzene at 145°C against polystyrene standard.

      ‡Incorporation ratio of 1, determined by 1H NMR analysis.

      §Determined by differential scanning calorimetry.

      ǁNo GPC signal was observed in 1,2-dichlorobenzene at 145°C probably because of oxidation (or other reaction) of the phosphine components at high temperatures inside the GPC columns.

      Supplementary Materials

      • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/3/7/e1701011/DC1

        Supplementary Materials and Methods

        fig. S1. Fineman-Ross plot for the copolymerization of ethylene and monomer 1i with Sc-5/[Ph3C][B(C6F5)4] at 20°C.

        fig. S2. Sulfur and vinyl coordination complexes and their relative free energies (in kilocalories per mole).

        fig. S3. Chain initiation and chain propagation processes of the polymerization of 1i with relative free energies (in kilocalories per mole) shown under the structures.

        fig. S4. Coordination site analysis for the incoming monomer.

        fig. S5. Schematic representations of the transition states showing steric hindrance influences.

        table S1. Homopolymerization of oxygen-containing α-olefin 1b by different rare-earth catalysts.

        table S2. Homopolymerization of sulfur-containing α-olefin 1i by different rare-earth catalysts.

        table S3. Data for Fineman-Ross plot.

        table S4. Energy decomposition analyses of transition states (energy in kilocalories per mole).

        table S5. Gas-phase zero-point correction [ΔΔEgas (in atomic units)] and gas-phase thermal correction to enthalpy [ΔΔHgas (in atomic units)] and to Gibbs free energy [ΔΔGgas (in atomic units)], single-point energy [Esp (in atomic units)] in solution, and relative free energy [ΔG (in kilocalories per mole)].

        References (3561)

      • Supplementary Materials

        This PDF file includes:

        • Supplementary Materials and Methods
        • fig. S1. Fineman-Ross plot for the copolymerization of ethylene and monomer 1i with Sc-5/[Ph3C][B(C6F5)4] at 20°C.
        • fig. S2. Sulfur and vinyl coordination complexes and their relative free energies (in kilocalories per mole).
        • fig. S3. Chain initiation and chain propagation processes of the polymerization of 1i with relative free energies (in kilocalories per mole) shown under the structures.
        • fig. S4. Coordination site analysis for the incoming monomer.
        • fig. S5. Schematic representations of the transition states showing steric hindrance influences.
        • table S1. Homopolymerization of oxygen-containing α-olefin 1b by different rare-earth catalysts.
        • table S2. Homopolymerization of sulfur-containing α-olefin 1i by different rare-earth catalysts.
        • table S3. Data for Fineman-Ross plot.
        • table S4. Energy decomposition analyses of transition states (energy in kilocalories per mole).
        • table S5. Gas-phase zero-point correction [ΔΔEgas (in atomic units)] and gas-phase thermal correction to enthalpy [ΔΔHgas (in atomic units)] and to Gibbs free energy [ΔΔGgas (in atomic units)], single-point energy [Esp (in atomic units)] in solution, and relative free energy [ΔG (in kilocalories per mole)].
        • References (3561)

        [Download PDF]

        Files in this Data Supplement:

      Stay Connected to Science Advances

      Navigate This Article