Fig. 4: Reaction diagram showing all discussed reactions and detected compounds under different pH conditions.

Background color and shapes indicate the pH conditions the compounds were detected at. The different panels show suggested formation pathways for the different compounds. Conversion of acetylene to unsaturated carboxylic acids via Reppe chemistry (a), conversion of acetylene into formic acid via an unkown pathway (b), condensation of acetaldehyde (c + e), dispropotionation of acetaldehyde leading to acetic acid and ethanol (d), Strecker reaction (f + g), michael addition followed by oxidation resulting in sulfonic acid (h), lactic acid formation (i).