Methods for forming rosin-derived cationic compounds are provided. The method can include attaching a cationic group to a conjugated diene on a hydrophenathrene-based ring of a resin acid (e.g., levopimaric acid, abietic acid, dehydroabietic acid, or a mixture thereof) to form a rosin-derived cationic compound. Attaching the cationic group to the conjugated diene on the hydrophenathrene-based ring of the resin acid can be achieved via a Diels-Alder reaction of a dienophile with the hydrophenathrene-based ring of the resin acid. Rosin-derived cationic compounds are also provided. The rosin-derived cationic compound can include a cationic group attached to a conjugated diene on a hydrophenathrene-based ring of a resin acid, wherein the rosin-derived cationic compound further comprises a carboxylic acid group.