I am fractionating poplar in 2-methyl tetrahydrofuran at 80°C with HCl as a catalyst, and then extracting the lignin by precipitating the solution with NaHCO3 and filtration. But the lignin that comes out is very dark in color, does not show signals in the 1H-13C 2D-HSQC NMR spectrum, and does not produce phenolic monomers. I particularly facing problems in precipitation of lignin from the 2-methyl tetrahydrofuran solution. I have to add way too much water and still, the filtered solution seems to have a lot of lignin-monomers lost in it!
What can I do to make the extraction conditions mild enough for lignin?
The addition of formaldehyde prevents lignin condensation reactions by forming 1,3-dioxane structures with –OH groups at the Cα and Cγ positions. The subsequent hydrogenolysis of structurally modified lignin results in near theoretical yields of monomers.
- Badges
- Science topic
- Similar topics
- Phytochemistry
- Extracts