Solvent-free polymerisation of rac-lactide at 180 °C using Zn(4, 5, 7, 8, 9)2. [LA]/[Zn]/[BnOH] = 10 000 : 1 : 30a.
| Init. | Time/min | Conv.b% | P m c | M n e | M n calc.d | Đ e | TOF/h−1h |
|---|---|---|---|---|---|---|---|
| Zn(4)2 | 3 | 74 | 0.57 | 28 100 | 35 750 | 1.62 | 148 000 |
| Zn(5)2 | 2 | 83 | 0.57 | 31 350 | 40 050 | 1.53 | 249 000 |
| Zn(5)2f | 4 | 74 | 0.00g | 32 050 | 35 750 | 1.16 | 111 000 |
| Zn(7)2 | 6 | 67 | 0.58 | 26 850 | 32 350 | 1.45 | 67 000 |
| Zn(7)2f | 6 | 56 | 0.00g | 28 050 | 27 050 | 1.15 | 56 000 |
| Zn(8)2 | 3 | 69 | 0.58 | 27 150 | 33 300 | 1.60 | 138 000 |
| Zn(9)2 | 12 | 65 | 0.62 | 24 400 | 31 400 | 1.68 | 32 500 |
a
Conditions: rac-LA (3 g), [LA]/[Zn]/[BnOH] = 10 000 : 1 : 30, solvent free.
b
Determined by 1H NMR spectroscopy.
c
Probability of racemic enchainment, determined by 1H{1H} NMR spectroscopy.
d
Theoretical molecular weight calculated from conversion (rounded to the nearest 50): {(conversion × 3 × Mn [LA]) + Mn [BnOH]}.
e
Determined from GPC (in tetrahydrofuran) referenced against polystyrene standards × 0.58.
f
l-Lactide used.
g
One peak present in 1H{1H} NMR spectrum.
h
TOF = [LA]t/([Zn] × t).