Ethyl-phenol production mechanism

Fig. 8.11. Enzyme mechanism for the production of ethyl-phenols by Brettanomyces sp.

Reactions of anthocyanins and flavanols take place much faster in the presence of acetaldehyde that is present in wine as a result of yeast metabolism and can also be produced through ethanol oxidation, especially in the presence of phenolic compounds, or introduced by addition of spirit in Port wine technology. The third mechanism proposed involves nucleophilic addition of the flavanol onto protonated acetaldehyde, followed by protonation and dehydration of the resulting adduct and nucleophilic addition of a second flavonoid onto the carbocation thus formed. The resulting products are anthocyanin flavanol adducts in which the flavonoid units are linked in C6 or C8 position through a methyl-methine bond, often incorrectly called ethyl-link in the literature. 

With few exceptions (c.g., DES), a causal relationship between exposure to a specific environmental agent and an adverse effect on human health operating via an endocrine disruption mechanism has not been established. Short-term screening studies could be developed and validated in an effort to elucidate the mechanism. Through controlled dose-response studies, it appears that these compounds (e.g., alkyl phenol ethylates and their degradation products, chlorinated dibenzodioxins and difurans, and polychlorinated biphenyls) can induce irreversible induction of male sex characteristics on females (impo-sex), which can lead to sterility and reduced reproductive performance. 

Ethyl (E) and (Z)-3-iodoacrylates form aryloxy- or amino-substituted (E)- and (Z)-ethylacrylates, respectively, in a DABCO(l,4-Diazabicyclo[2.2.2]octane)-mediated reaction with a wide variety of phenols and V-heterocycles in DMF. The reactions are stereospecific and give the product in good to excellent yields (75-98%). Several possible mechanisms are suggested for these reactions. 

---