As described above, one of the most sought-after applications of the Kolbe reaction involves upgrading biomassderived carboxylic acids to high-value products, an aspiration yet to be realized. The practical conditions and broad reaction generality achieved by rAP-Kolbe reaction can finally address this longstanding challenge even on scale. Figure exemplifies the realization by enlisting biomass-derived acids 1 and 30 to produce 1,19eicosadiene 4 and 2,7-octadione 12 on 200 and 300 mmol scale, respectively. No precaution to air and moisture was necessary when performing large-scale reactions. For the first time, 4 can now be considered a biomass-derived material that can potentially be accessible in bulk quantities. The terminal olefins can be readily converted into a variety of functional groups by using well-established reactions, providing additional new building blocks 33-39 with potential use for polymer additives or constructing degradable alternative of commodity polymers (Figure ). Degradable polymers are becoming increasingly more important to realize closed-loop recycling. Accessing such polymers from biomass-derived building blocks is attracting strong interest, as evidenced in the recent disclosure of biomass-derived polyesters and polycarbonates. As a proof of concept for this possibility, a new polymer 40 was synthesized from monomers 13 and 38 derived from rAP-Kolbe reaction by connecting them through a ketal linkage under anhydrous conditions (cat. CSA, toluene) -an underutilized motif in degradable polymers (Figure ). Polymer 40 can be subsequently degraded under aqueous acidic conditions, an orthogonal degradation to polyesters or polycarbonates that require basic conditions. Furthermore, the highly practical conditions can be easily adapted to access to unnatural amino acid 22 on scale, demonstrating potential adoption of this reaction to the fine-chemical industry (Figure ). Figure outlines a series of experiments that provide a qualitative mechanistic rationale for the rAP-Kolbe reaction. The net transformations are oxidative decarboxylation balanced by acetone reduction (Figure ). Not surprisingly, oxidative decarboxylation invariably generates free radicals as evidenced by cyclization of the 5hexenyl radical derived from acid 41 as well as the Giese-type adduct 46 produced from the decarboxylation of 45 in the presence of methyl acrylate. Acetone reduction was confirmed by the detection of 0.5 equiv. of isopropanol in crude 1 H NMR, indicating that acetone is used as sacrificial electron-and proton-acceptor (Fig. ). How does the rAP-Kolbe reaction achieve strikingly different levels of chemoselectivity relative to the classic Kolbe reaction? Surprisingly, this fundamental reactivity difference may stem, in a large part, from the local acidity at the electrode surface. In general, DC electrolysis creates local areas of enhanced acidity surrounding the anode at the microscopic level (regardless of stirring rate) through oxidation of solvent, water, or the substrate itself, known as electrogenerated acid. Counterintuitive to the fact that the reaction solution is partially neutralized, this phenomenon leads to protonation of carboxylate at the anode. As the direct oxidation of a carboxylic acid is not favored, electrode passivation or oxidation of other functional groups outcompetes decarboxylative processes (that require a carboxylate). In contrast, rAP skirts this issue via fast polarity switching such that an anodic phase does not last long enough to create a persistent acidic electrode surface (due to rapid oscillation). As a result, oxidation of the deprotonated form (carboxylate) readily takes place in preference to other functional groups. To support this hypothesis, a compound sensitive to acidic deprotection (48) was added in both DC-and rAP-Kolbe reactions (Figure ). DC electrolysis generated the parent alcohol 50 in 52% yield with the formation of Kolbe dimer 49 in 37% yield, whereas the probe 48 was almost intact under rAP conditions with much higher yield of 49. In addition to these experiments, a pH indicator (bromophenol blue) was added to the reaction solution to visualize the pH. As expected, a low pH was detected around the anode during DC electrolysis, whereas no visible pH difference was observed under rAP. Finally, a cyclic voltammogram of 2 was recorded with or without base to understand the correlation between pH and the functional groups to be oxidized (Figure ). An oxidation peak appeared above 2V without addition of a base (left graph), which is in good agreement with the arene oxidation potential reported in the literature. Upon addition of 1 equiv. of Me4N•OH, a new peak appeared around 1.3 V (right graph), which is the typical oxidation potential of alkyl carboxylates. Taken together, these observations explain the intriguing reactivity switch illustrated in Table : 2 is oxidized in its neutral form under DC electrolysis due to the locally acidic anode environment, resulting in arene oxidation. In contrast, 2 is oxidized as its deprotonated form under rAP, leading to selective decarboxylation without oxidizing the arene. The modulation of electrode pH is an overlooked phenomenon in synthetic organic electrochemistry that further illustrates the profound effect that altered waveforms can have on the course of a reaction.