Cellulose Dissolution and Biomass Pretreatment Using Quaternary Ammonium Ionic Liquids Prepared from H-, G-, and S-Type Lignin-Derived Benzaldehydes and Dimethyl Carbonate

Abstract

The synthesis of novel benzyl alkylammonium ionic liquids (IL) from starting materials derived from grass, softwood, and hardwood lignin was performed using batch reactor systems followed by facile methyl carbonate ion exchange chemistry. Approximately 90% yields of the ILs were achieved over three synthetic steps, and all novel materials were fully characterized by 1 H and 13 C nuclear magnetic resonance spectroscopy and high-resolution mass spectrometry. The structure−activity relationships of the lignin-derived ILs were evaluated for their ability to dissolve microcrystalline cellulose and convert switchgrass to fermentable sugars (glucose and xylose). All ILs tested, including a 1:1:1 mixture of ILs prepared from vanillin, syringaldehyde, and panisaldehyde yielded 52−71% of the glucose and 50−71% of the xylose from the total amount of glucan and xylan available in the raw feedstock. These data compared well to the yields obtained from switchgrass pretreatment with the IL, 1-ethyl-3methyl imidazolium acetate, which gave 71% of the glucose and 63% of the xylose from the total glucan and xylan in the raw feedstock, respectively.

Synthesis, Antibiotic Structure-Activity-Relationships, and Cellulose Dissolution Studies of New Room-Temperature Ionic Liquids Derived from Lignin

“…3. For compound 8, cellulose precipitation was observed at 4 wt% at 120 o C, which is in good agreement with previous studies compound 8 at 100 o C [38]. Cellulose dissolution was readily observed in compounds 9 and 10 at 2 wt% at 100 o C. To further examine cellulose solubility, washed samples of cellulose precipitated from ILs 8-10 (2 wt%) were centrifuged and analyzed by FTIR.…”

“…Compounds 2 and 4 were prepared from compounds and 5, respectively, using ion exchange. Compounds 6-8 were prepared using CBILS™ methyl carbonate chemistry as reported elsewhere [38].…”

“…Quaternary ammonium ILs have diverse engineering applications [35], and have been listed as suitable COVID-19 disinfectants for hard, non-porous surfaces [36]. Our research focuses on biomass applications using benzylammonium ionic liquids and deep eutectic solvents derived from lignin [37][38][39], and we have recently demonstrated isolation techniques for aminophenol IL precursors from oxidized kraft lignin [40].…”

“…Diez et al prepared a series of trimethyl benzylammonium acetate ILs (6-8) from 4-methoxy benzaldehyde, syringaldehyde, and vanillin, respectively representing major oxidative depolymerization products from H-, S-and G-type lignin [38]. Though these compounds remained solid at room temperature, cellulose dissolution, switchgrass pretreatment, mass balances, and sacchari cation yields for 6-8 were comparable to 1.…”

Synthesis, antibiotic structure–activity relationships, and cellulose dissolution studies of new room-temperature ionic liquids derived from lignin

“…Our research focuses on biomass applications using benzylammonium ionic liquids and deep eutectic solvents synthesized from lignin depolymerization products, such as benzaldehydes [ 38 – 40 ], and we have recently demonstrated isolation techniques for aminophenol IL precursors from oxidized kraft lignin [ 41 ]. Diez et al prepared a series of trimethyl benzylammonium acetate ILs ( 6 – 8 ) from 4-methoxy benzaldehyde, syringaldehyde, and vanillin, respectively, representing major oxidative depolymerization products from H-, S- and G-type lignin [ 39 ]. Though compounds 6 – 8 remained solid at room temperature, their utility as solvents for switchgrass pretreatment were comparable to 1 .…”