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.