Often when I am tagging organic-chemistry there seems to be a lack of tags beyond this very broad one. reaction-mechanism seems to be very popular at the moment and generates quite a lot of good questions but doesn't really help to narrow down questions very much. Since the most obvious way to order organic chemistry (and the way in which most textbooks do it) seems to be by functional group, I think we should start tagging organic chemistry questions in this way. As someone who is very interested in learning about organic chemistry, I am often looking for information on different functional groups, and being able to go to the appropriate tag and browse through questions about that group would be very useful.
Functional group tags that already exist: alcohols, aromatic-compounds, halides, carbonyl-compounds, thiols (rarely used), halocarbons (this should probably be merged with halides), carbohydrates, fats, cyclohexane (this seems too specific so we might want to be delete it or create an alkane tag and merge them).
Tags that I think should exist: carboxylic-acids (>200 search results), esters (>230 results), alkanes (>170 results), alkenes (>240), alkynes (>80), amines (>220), nitro-compounds (>80). There are probably some more that I've missed to feel free to add more suggestions.