Fermentation converts pyruvate into ethanol through the intermediate acetaldehyde. Pyruvate decarboxylase starts this process by converting pyruvate into acetaldehyde and carbon dioxide. First, acrolein is formed in a Knoevenagel condensation from the acetaldehyde and formaldehyde. Alcohol metabolism generates genotoxic acetaldehyde and reactive oxygen species. Ethylene undergoes oxidation by palladium to give acetaldehyde. It is produced industrially by the reaction of formaldehyde, acetaldehyde, and ammonia. Smaller aldehydes are more soluble in water, formaldehyde and acetaldehyde completely so. Many disulfiram-like drugs act as inhibitors of acetaldehyde dehydrogenase similarly to disulfiram. Ethylene oxide is isomeric with acetaldehyde and with vinyl alcohol. ALDH2 plays a crucial role in maintaining low blood levels of acetaldehyde during alcohol oxidation. Adh2 catalyzes the reverse reaction, consuming ethanol and converting it to acetaldehyde. These convert the ethanol into acetaldehyde (an intermediate more toxic than ethanol). Adh1 is the major enzyme responsible for catalyzing the fermentation step from acetaldehyde to ethanol. Glyoxal may be synthesized in the laboratory by oxidation of acetaldehyde with selenious acid. The method is used in the production of ethyl acetate from acetaldehyde.