Passivity of hypercrosslinked sorbents

We chose cyclohexanone (I) as a diagnostic probe. Oxidation of cyclohexanone yields easily 1,2-cyclohexanedione (II) and then adipic acid (III)  

Two commercially available neutral hypercrossHnked polystyrene resins, MN-200 and MN-250, as well as the industrially used activated carbon SKT-6A (Russia) were loaded with cyclohexanone by a prolonged exposure of the materials to its vapors in a dessicator at ambient temperature (mosdy, 25°C). The sorption capacity for both polymeric samples amounted to 400—500mg/g. Afterward, the cyclohexanone-loaded sorbents were incubated at 85°C. At random intervals as indicated in Table 10.3, portions of each sorbent were washed with acetone and then a small dose of the acetone extract was injected into a gas chromatograph. 

Results given in Table 10.3 show that MN-250 and MN-200 are inert materials even after 360 h of heating no traces of diketone II could be detected in the acetone extracts, which only contained cyclohexanone. Contrary to this, the activated carbon provoked an intensive transformation of cyclohexanone. After heating the preloaded carbon sample for 48 h at 85°C, the amount of diketone II formed was found to reach 9 mg/g. Naturally, on further heating of the sample, oxidation of the adsorbed cyclohexanone by the carbon becomes increasingly pronounced. 

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