TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Method: The method further involves after removing the biphasic mixture from the digestion unit, separating the aqueous phase from the organic phase; after separating the aqueous phase from the organic phase, separating the slurry catalyst from at least a portion of the aqueous phase; and after separating the slurry catalyst from at least a portion of the aqueous phase, returning a portion of the aqueous phase containing the slurry catalyst to the digestion unit. The method further involves exposing the alcoholic component or other water-soluble organic compound from the aqueous phase to a condensation catalyst, to form a condensation reaction product; prior to exposing the alcoholic component or other water-soluble organic compound from the aqueous phase to the condensation catalyst, separating the alcoholic component or other water-soluble organic compound from the aqueous phase; and returning at least a portion of the condensation reaction product to the digestion unit while heating the cellulosic biomass solids and the digestion medium. The method further involves after removing the biphasic mixture from the digestion unit, separating the aqueous phase from the organic phase; and performing a cross-flow filtration on the organic phase before returning the phenolic solvent to the digestion unit. The method further involves removing at least a portion of the alcoholic component from the digestion unit; exposing the alcoholic component to a condensation catalyst, to form a condensation reaction product; returning a portion of the condensation reaction product to the digestion unit while heating the cellulosic biomass solids and the digestion medium. In the method, at least a portion of the slurry catalyst accumulates in the aqueous phase of the biphasic mixture. The step of separating the slurry catalyst from at least a portion of the aqueous phase involves performing a cross-flow filtration on the aqueous phase. The aqueous phase and the slurry catalyst are returned to the digestion unit such that upwardly directed fluid flow is established in it. The portion of the aqueous phase separated from the slurry catalyst also contains at least a portion of the alcoholic component or other water-soluble organic compound in it. The step of separating the alcoholic component or other water-soluble organic compound from the aqueous phase involves performing an extraction of the aqueous phase with an organic extraction solvent. The organic extraction solvent comprises the condensation reaction product, which is recirculated to the aqueous phase following its formation. The condensation reaction product is returned to the digestion unit as an upwardly directed fluid flow. The organic phase of the biphasic mixture contains the lignin, the organic solvent, the phenolic solvent, and the remainder of the slurry catalyst. The lignin is converted into the phenolic solvent after separating the aqueous phase from the organic phase. The phenolic solvent is returned to the digestion unit such that upwardly directed fluid flow is established in it. The organic solvent comprises an alcohol or a ketone that is not fully miscible with water. The lignin is converted into the phenolic solvent external to the digestion unit. The lignin is converted into the phenolic solvent by thermally depolymerizing the lignin, and/or chemically hydrolyzing the lignin. The step of thermally depolymerizing the lignin involves heating the lignin to a temperature of at least 270 degrees C in the presence of molecular hydrogen and the slurry catalyst. The condensation reaction product is returned to the digestion unit as an upwardly directed fluid flow. The alcoholic component is formed by a catalytic reduction reaction of soluble carbohydrates, where the soluble carbohydrates are derived from the cellulosic biomass solids. Preferred Components: The organic solvent comprises at least one phenolic compound. The phenolic compounds are selected from eugenol, dihydroeugenol, propoxylated phenols, and/or methoxypropoxylated phenols. EXAMPLE - No suitable example is given.