article reviews our work on the living polymerization of olefins using dMMAO
combined with certain dimethyltitanium complexes.
2 Living Polymerization of Propene with a Chelating
Diamidodimethyltitanium
2.1 Activation with dMMAO
McConville et al. demonstrated that living polymerization of 1-alkene proceeded
with a chelating diamidodimethyltitanium (1) activated by B(C 6 F 5 ) 3 at 23
C in bulk
or CH 2 Cl 2 solution [10]. The addition of toluene significantly retarded the activity
because the active species formed a stable complex with toluene. They reported that
the active species was deactivated in the absence of 1-alkene via the reaction shown
in Scheme 1 [11]. These results prompted us to investigate propene polymerization
with 1 activated by dMMAO, which was prepared from MMAO by repetitions of
vacuum drying and successive re-dissolving in heptane [9].
Figure 1 displays the
1 H NMR spectra of MMAO and dMMAO in tetrahydrofuran-d 8 . The contents of each Al species were calculated from the relative intensities
of the
1 H NMR spectrum, which indicates that the treatment decreased the
i Bu 3 Al
Scheme 1 Deactivation of 1-B(C 6 F 5 ) 3 [11]
Fig. 1
1
H NMR spectra of MMAO (a) and dMMAO (b) in THF-d 8 [13]
Trialkylaluminum-Free Modified Methylaluminoxane as a Cocatalyst for Living. . .
145
combined with certain dimethyltitanium complexes.
2 Living Polymerization of Propene with a Chelating
Diamidodimethyltitanium
2.1 Activation with dMMAO
McConville et al. demonstrated that living polymerization of 1-alkene proceeded
with a chelating diamidodimethyltitanium (1) activated by B(C 6 F 5 ) 3 at 23
C in bulk
or CH 2 Cl 2 solution [10]. The addition of toluene significantly retarded the activity
because the active species formed a stable complex with toluene. They reported that
the active species was deactivated in the absence of 1-alkene via the reaction shown
in Scheme 1 [11]. These results prompted us to investigate propene polymerization
with 1 activated by dMMAO, which was prepared from MMAO by repetitions of
vacuum drying and successive re-dissolving in heptane [9].
Figure 1 displays the
1 H NMR spectra of MMAO and dMMAO in tetrahydrofuran-d 8 . The contents of each Al species were calculated from the relative intensities
of the
1 H NMR spectrum, which indicates that the treatment decreased the
i Bu 3 Al
Scheme 1 Deactivation of 1-B(C 6 F 5 ) 3 [11]
Fig. 1
1
H NMR spectra of MMAO (a) and dMMAO (b) in THF-d 8 [13]
Trialkylaluminum-Free Modified Methylaluminoxane as a Cocatalyst for Living. . .
145