What does the term "vinyl" describe in organic chemistry?

The term "vinyl" in organic chemistry refers specifically to the functional group or substituent characterized by the structure CH₂=CH-. This indicates a two-carbon unit with a double bond between the two carbon atoms. The vinyl group is derived from ethylene (ethene) and is commonly encountered in various organic compounds, particularly in the context of polymer chemistry, where it can contribute to the formation of larger structures like polyvinyl chloride (PVC).

Other choices represent different groups or structures: CH₃- corresponds to a methyl group, CH₃-CH₂- depicts an ethyl group, and CH₃-CH= shows a different type of substituent where there is no clear vinyl character since the double bond is not properly positioned to exhibit the vinyl characteristics. Thus, the correct identification of the vinyl group is crucial for understanding the reactivity and properties of molecules that contain this functional unit.