Feasibility of nanocrystalline cellulose production by endoglucanase treatment of natural bast fibers

Whereas straw management presents a continuing challenge among farmers, tremendous opportunities may exist within the natural fibers in terms of value- added products or chemicals. This research provides the first assessment and demonstration of feasibility of an enzyme-assisted production of nanocrystalline cellulose (NCC) from hemp and flax fibers. A newly cloned endoglucanase (AoEG), derived from Aspergillus oryzae and characterized to be a thermostable enzyme with a half-life of 50. h at 50. \ub0C was used for the hydrolysis. Atomic force microscopy (AFM) imaging of NCC produced from acid swollen cellulose and flax fibers indicated that they form aggregated network, showing rod-like nanofibrils of about 10. nm in height, and 200. nm in length. The yield of NCC using physical pretreatment only or combined physical-chemical pretreatment was compared. The highest yield of NCC was obtained under the conditions of 300. mg of flax fiber treated by 100. IU enzyme at 50. \ub0C for 24. h after pretreatment of the fibers by sonication-microwave in 2% NaOH solution.Peer reviewed: YesNRC publication: Ye

Novel tocopherol derivatives. Part 32: On the bromination of pyrano[3,2-f]chromenes related to γ-tocopherol

While bromination of γ-tocopherol (2) with elemental bromine affords 5-bromo-γ-tocopherol quantitatively (3), the analogous reaction of its truncated model compound, 2,2,7,8-tetramethylchromanol (2a) is known to be accompanied by side reactions and to produce hitherto unknown byproducts. These compounds originate from pyrano[3,2-f]chromene (6), a byproduct in the synthesis of model compound 2a, which affords bromochromene 7 as the major product. The reaction mechanism was shown to proceed via chromene 8 and its 1,2-dibromo addition compound 9, which eliminates HBr in an E1 process to finally afford 7. Analytical data including crystal structures of both 6 and 7 are reported