The reaction of sugar with oxygen is as follows:
C₁₂H₂₂O₁₁ + 12 O₂ → 12 CO₂ + 11 H₂O
When in the presence of pure oxygen, sucrose (table sugar) will not form caramel, in fact it will combust into carbon dioxide and water like any other carbohydrate.
Caramel is actually formed by slowly heating sucrose to high temperatures of around 170 °C resulting in thermal decomposition. This essentially removes molecules of water from the sucrose which results in the compound isomerizing and eventually polymerizing to form caramel. The chemical make up of caramel is the same as sucrose, so it will still be composed of carbon, hydrogen and oxygen.
