Process intensification of the ionoSolv pretreatment: effects of biomass loading, particle size and scale-up from 10 mL to 1 L.

The ionoSolv process is one of the most promising technologies for biomass pretreatment in a biorefinery context. In order to evaluate the transition of the ionoSolv pretreatment of biomass from bench-scale experiments to commercial scale, there is a need to get better insight in process intensification. In this work, the effects of biomass loading, particle size, pulp washing protocols and 100-fold scale up for the pretreatment of the grassy biomass Miscanthus giganteus with the IL triethylammonium hydrogen sulfate, [TEA][HSO4], are presented as a necessary step in that direction. At the bench scale, increasing biomass loading from 10 to 50 wt% reduced glucose yields from 68 to 23% due to re-precipitation of lignin onto the pulp surface. Omitting the pulp air-drying step maintained saccharification yields at 66% at 50 wt% loading due to reduced fiber hornification. 100-fold scale-up (from 10 mL to 1 L) improved the efficacy of ionoSolv pretreatment and increasing loadings from 10 to 20 wt% reduced lignin reprecipitation and led to higher glucose yields due to the improved heat and mass transfer caused by efficient slurry mixing in the reactor. Pretreatment of particle sizes of 1-3 mm was more effective than fine powders (0.18-0.85 mm) giving higher glucose yields due to reduced surface area available for lignin re-precipitation while reducing grinding energy needs. Stirred ionoSolv pretreatment showed great potential for industrialization and further process intensification after optimization of the pretreatment conditions (temperature, residence time, stirring speed), particle size and biomass loading. Pulp washing protocols need further improvement to reduce the incidence of lignin precipitation and the water requirements of lignin washing.

Fused Ring Molecular Scaffold with 3D Architecture for Constrained Peptidomimetics: Polymer-Supported Stereoselective Synthesis of Tetrahydrobenzo[e]pyrazino[2,1-c][1,2,4]thiadiazinone 6,6-dioxide via N-Acyl Iminiums.

3,4,4a,5-Tetrahydrobenzo[e]pyrazino[2,1-c][1,2,4]thiadiazin-1(2H)-one 6,6-dioxides, molecular scaffolds with 3D architecture, were synthesized on solid supports via tandem N-acyl iminium ion cyclization followed by nucleophilic addition. The modular synthesis proceeded under mild conditions using commercially available building blocks and provided crude products with respectable purity. The synthesized compounds are applicable as fused nitrogenous heterocyclic compounds in drug discovery and as constrained peptidomimetics incorporated into a peptide backbone.

Knoevenagel reaction in [MMIm][MSO4]: synthesis of coumarins.

The ionic liquid 1,3-dimethylimidazolium methyl sulfate, [MMIm][MSO4], together with a small amount of water (the amount taken up by the ionic liquid upon exposure to air), acts efficiently as both solvent and catalyst of the Knoevenagel condensation reactions of malononitrile with 4-substituted benzaldehydes, without the need for any other solvent or promoter, affording yields of 92%-99% within 2-7 min at room temperature. When L-proline is used as an additional promoter to obtain coumarins from o-hydroxybenzaldehydes, the reaction also proceeds in high yields. Work-up is very simple and the ionic liquid can be reused several times. Some of the coumarins obtained are described for the first time.