Final answer:
Ethanol is the compound that is NOT a phenolic among the options provided (lignin, tannin, ethanol, vanillin), as it lacks the characteristic benzene ring bonded to an -OH group that defines phenolic compounds.
Step-by-step explanation:
The student asked which of the following is NOT a phenolic compound out of lignin, tannin, ethanol, and vanillin. Phenolic compounds are characterized by bearing a phenol group, which consists of a benzene ring with an -OH group attached to it. This group is present in natural products and plays various roles ranging from plant defense mechanisms to contributing to the flavor and aroma of certain foods.
Examining the options given: