Synthesis of lignin-based thermoplastic copolyesters
Sebacoyl dichloride was synthesized by reacting sebacic acid
(8.92 g, 44.2 mmol) with thionyl chloride (20 mL). Evaporation
of the excess thionyl chloride yielded the sebacoyl dichloride
(Erdmann and Uhrich, 2000). 22.1 mL of 2 mol/L sebacoyl dichloride
solution in dry DMF was added dropwise into a three-necked flask
containing a solution of triethylamine (13.82 g), PEG (5.00 g) and
lignin (5.00 g) in anhydrous DMF (60 mL) over 0.5 h at room temperature under a nitrogen atmosphere. The mixture was allowed
to react for various time at specified temperatures before quenching with deionized water. The solid precipitation was collected
by vacuum filtration and washed with boiling deionized water
(400 mL × 5). The products were collected and dried under vacuum at 60 ◦C for 24 h. In order to reduce the cost of disposes major
wastes generated by the system, we propose following approaches.
Excess thionyl chloride could be recycled by reduced pressure distillation. Since sebacic acid reacted with thionyl chloride under