Revisiting the Hitherto Elusive Cyclohexanehexone Molecule: Bulk Synthesis, Mass Spectrometry, and Theoretical Studies.

The cyclohexanehexone (C6O6) octahydrate molecule was claimed to be synthesized as early as 1862. However, the chemical in the 1862 study and the chemicals used in most of the existing studies and sold by most chemical vendors are actually dodecahydroxycyclohexane dihydrate (C6(OH)12·2H2O). Here we revisit our bulk synthesis method of C6O6 by the dehydration of the C6(OH)12·2H2O material, and report the mass spectrum of C6O6 that has been highly challenging to obtain owing to its high sensitivity toward ambient conditions. A new home-built electrospray ionization mass spectrometry setup in a glovebox is utilized to detect C6O6 in the form of C6O6H-. Tandem mass spectrometry MSn (n = 2-4) presents consecutive losses of CO molecules, further confirming the structure of C6O6. Theoretical calculations are performed to recover the chemical bonding of C6O6 and to rationalize the synthetic method. This work provides a benchmark understanding of the historically elusive C6O6.