Quantitative analysis of the formation of monodisperse cello-oligomers obtained by phosphoric acid hydrolysis

Hydrolysis of cellulose in concentrated phosphoric acid is known to give two distinctive mono-disperse cello-oligomers: the degree of polymerization (DP) of 7 and 15. To understand the formation mechanism of monodisperse cello-oligomers, the transition of DP during phosphoric hydrolysis was monitored by size-exclusion chromatography combined with multiangle laser-light scattering analyses (SEC/MALLS). The obtained results suggested that not the hydrolysis at a specific length but random hydrolysis was likely. The rate of hydrolysis slowed down when the DP reached around 40, and the pool of cello-oligomers appeared at the incubation of 35 days. Then, the mono-disperse cello-oligomers were recovered from the pool of cello-oligomers by fractionation based on the solubility difference.

Automated summary

Hydrolysis of cellulose in concentrated phosphoric acid can produce two distinct monodisperse cello-oligomers, with degrees of polymerization (DP) of 7 and 15. By monitoring the DP transition during phosphoric hydrolysis using size-exclusion chromatography and multiangle laser-light scattering analyses, it was found that the hydrolysis process is likely to be random instead of specific length hydrolysis. The hydrolysis rate slows down when the DP reaches around 40, and a pool of cello-oligomers appears after 35 days. Monodisperse cello-oligomers are then recovered from this pool through fractionation based on solubility difference.