Oxides of Carbon - New Oxides

New Oxides

Many new stable or metastable oxides have been synthesized since the 1960s, such as:

• C₁₀O₈, benzoquinonetetracarboxylic dianhydride (Hammond, 1963).
• C₆O₆, ethylenetetracarboxylic dianhydride, a stable isomer of cyclohexanehexone (Sauer and others, 1967).
• C₁₂O₁₂ or C₆(C₂O₄)₃, hexahydroxybenzene trisoxalate (Verter and Dominic, 1967); stable as a tetrahydrofuran solvate.
• C₁₀O₁₀ or C₆O₂(C₂O₄)₂, tetrahydroxy-1,4-benzoquinone bisoxalate (Verter and others, 1968); stable as a tetrahydrofuran solvate.
• C₈O₈ or C₆O₂(CO₃)₂, tetrahydroxy-1,4-benzoquinone biscarbonate (Nallaiah, 1984); decomposes at about 45–53 °C.
• C₉O₉ or C₆(CO₃)₃, hexahydroxybenzene triscarbonate (Nallaiah, 1984); decomposes at about 45–53 °C.
• C₂₄O₆, a cyclic trimer of the biradical 3,4-dialkynyl-3-cyclobutene1,2-dione -C≡C-(C₄O₂)-C≡C- (Rubin and others, 1990);
• C₃₂O₈, a tetramer of 3,4-dialkynyl-3-cyclobutene1,2-dione (Rubin and others, 1990);
• C₄O₆, dioxane tetraketone or dimeric oxalic anhydride (Strazzolini and others, 1998); stable in Et₂O at −30 °C, decomposes at 0 °C.
• C₁₂O₆, hexaoxotricyclobutabenzene (Hamura and others, 2006)

Many relatives of these oxides have been investigated theoretically, and some are expected to be stable, such as other carbonate and oxalate esters of tetrahydroxy-1,2-benzoquinone and of the rhodizonic, croconic, squaric, and deltic acids.