The mechanochemical selectivity of PAO was determined by us before to 42-66%, depending on the sonication conditions and Mn. We hence ultrasonicated PMKO with Mn = 103 kDa (PMKO103) in solution using an immersion probe sonicator at 20 kHz (Figure ). Variations in solvent, amplitude, and mass concentration (Table ) consistently confirmed the mechanochemical generation of the ketone with selectivities of 44 to 57%, which was verified by the dedicated synthesis of a PMA-substituted ketone control compound. Identical experiments for PTKO92 yielded selectivities of 46 to 57% (Table ). Polar solvents, and in particular H2O, equally accelerated the mechanochemical bond scission for all carbamoyloximes, as would be expected due to stronger inertial cavitation. The product distributions and mechanochemical selectivities remained largely unaffected. and, entries 1-4) including a PMA-appended ketone control compound 23. (C) Comparative plot of the rate constants (calculated according to the initial rates method) against the starting molar mass Mn,start for every sonicated sample of PAO, PMKO, and PTKO. Mean values ± SD from the mean. N = 2 independent sonications.