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.