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. 2018 Oct 23;8(63):36025–36033. doi: 10.1039/c8ra07733a

Enzymatic ROP of l-lactide and ε-caprolactone under different reaction conditionsa.

Trial Substrate Solvent (water content) T (°C) Reaction time (days) Conversion (%) Yield (%) M w b (Da) PDI
1 l-Lactide No solvent 130 7 85.3 36 12 400 1.14
2 l-Lactide Dimethylacetamide (0.01 wt%) 130 7 95.2 46 11 500 1.54
3 l-Lactide [BMIM][PF6] (0.01 wt%) 130 7 92.4 24 11 900 2.15
4 l-Lactide [BMIM][Tf2N] (0.01 wt%) 130 7 94.5 6 13 000 1.48
5 l-Lactide [CH3OCH2CH2-PEt3][Tf2N] (0.01 wt%) 130 7 84.9 12 21 100 1.89
6 l-Lactide [CH3OCH2CH2-PBu3][Tf2N] (0.01 wt%) 130 7 86.3 34 17 600 2.13
7 l-Lactide [CH3OCH2CH2-PBu3][Tf2N] (1.7 wt%) 130 7 96.5 28 12 600 2.38
8 l-Lactide [CH3OCH2CH2-PBu3][Tf2N] (0.01 wt%, 0.5 mL) 130 7 75.5 10 12 200 1.84
9 l-Lactide [CH3OCH2CH2-PBu3][Tf2N] (0.01 wt%, 1.0 mL) 130 7 79.2 6 6800 1.84
10 l-Lactide [CH3OCH2CH2-PBu3][beti] (0.02 wt%) 130 7 69.2 32 14 500 2.19
11 l-Lactide [CH3(OCH2CH2)2-PBu3][Tf2N] (0.02 wt%) 130 7 74.5 12 15 400 1.38
12 l-Lactide [CH3(OCH2CH2)3-PBu3][Tf2N] (0.02 wt%) 130 7 87.2 14 13 400 1.38
13 l-Lactide [CH3(OCH2CH2)4-PBu3][Tf2N] (0.01 wt%) 130 7 87.5 4 14 000 1.71
14 l-Lactide [CH3(OCH2CH2)4-PBu3][Tf2N] (0.04 wt%) 130 7 80.0 20 13 200 1.97
15 l-Lactide [MeOCH2CH2-Et-Im][Tf2N] (0.03 wt%) 130 7 90.0 10 23 000 1.55
16 l-Lactide [MeOCH2CH2-Py][Tf2N] (0.03 wt%) 130 7 78.6 14 17 300 1.29
17 l-Lactide [MeOCH2CH2-Et3N][Tf2N] (0.03 wt%) 130 7 92.5 20 19 000 1.58
18 l-Lactide [MeOCH2CH2-Me-Pip][Tf2N] (0.03 wt%) 130 7 88.0 16 11 300 1.76
19 ε-Caprolactone No solvent 70 2 96.8 37 13 800 1.71
20 ε-Caprolactone [BMIM][PF6] (0.01 wt%) 70 2 87.8 55 18 500 1.94
21 ε-Caprolactone [CH3OCH2CH2-PBu3][Tf2N] (0.02 wt%) 70 2 96.9 48 18 900 1.59
22 ε-Caprolactone [CH3OCH2CH2-PBu3][beti] (0.02 wt%) 70 2 52.1 15 9100 1.19
23 ε-Caprolactone [CH3(OCH2CH2)2-PBu3][Tf2N] (0.02 wt%) 70 2 70.1 30 14 300 1.35
24 ε-Caprolactone [MeOCH2CH2-Et-Im][Tf2N] (0.03 wt%) 70 2 95.7 42 12 300 1.60
25 ε-Caprolactone [MeOCH2CH2-Py][Tf2N] (0.03 wt%) 70 2 94.3 32 16 200 1.34
26 ε-Caprolactone [MeOCH2CH2-Et3N][Tf2N] (0.03 wt%) 70 2 96.4 11 17 300 1.39
27 ε-Caprolactone [MeOCH2CH2-Me-Pip][Tf2N] (0.03 wt%) 70 2 96.1 11 18 100 1.69
a

General reaction conditions (unless otherwise noted): 0.5 g of l-lactide or ε-caprolactone, 0.25 mL of solvent, 100 mg of Novozym 435, gentle stirring (210 rpm) at 130 or 70 °C for 7 or 2 days. GPC-derived Mw values were based on results calibrated using polystyrene standards.

b

Based on GPC analysis.