Parameters affecting in vitro monolignol couplings during dehydrogenative polymerization in the presence of peroxidase and H2O2

Dehydrogenative polymers (DHP) were synthesized by end-wise coupling (Zutropfverfahren) with coniferyl alcohol in a mixture of organic solvents (isopropyl alcohol, dioxane, acetonitrile) and buffer with various ratios in the presence of horse radish peroxidase and H2O2. When the ratio of organic solvent to buffer increased, DHP yield decreased from 78.3% to 42.7% in dioxane/buffer and from 77.8% to 43.2% in acetonitrile/buffer, whereas DHP yield in isopropyl alcohol/buffer was almost constant from 78.4% to 74.0%. The effects of adding organic solvents to the buffer were also evaluated with GPC analysis of DHP and frequency of β-O-4 linkage in DHP by DFRC analysis.