Abstract: Disclosed herein are systems and methods of depolymerizing a lignin component of a lignin-containing material. The method comprising contacting the lignin-containing material with a solvent and optionally a catalyst at a temperature in the range of 180-300° C. and at a maximum operating pressure of less than 10 barG during the depolymerization of the lignin component of the material and collecting at least one volatile stream comprising one or more depolymerized lignin products. In an embodiment, the step of contacting is carried out in a reactive distillation reactor, and the step of collecting comprises concurrently collecting at least one volatile stream via distillation apparatus connected to the reactive distillation reactor, at least one of the one or more depolymerized lignin products comprises a substituted phenol having the following general formula: (I) wherein R1 is H, methyl, ethyl, n-propyl, propenyl, or allyl, and R2 and R3 are independently selected from H or methoxy group.