The word formation process that yielded the word coon is called (fore-)clipping:
raccoon > coon
Other examples of fore-clipping include: bot (robot), chute (parachute), roach (cockroach), coon (raccoon), gator (alligator), phone (telephone), pike (turnpike), varsity (university), net (Internet).
For some of these examples, the clipping simply reverts a previous compounding: notably, it preserves existing word stems.
But not for raccoon, which comes from Algonquian arahkun: there does not seem to be anything to revert, and the word simply becomes one syllable shorter.
Similarly, bot does not preserve word stems: robot derives from robota (forced labor), which in turn (reportedly) derives from PIE *orbh-.
I wonder whether there is a driving force that helped establish these words as lexical units (such as, a strong preference for one-syllable words), and whether there is a pattern for how words such as these can be born, or whether they emerged and caught on by mere chance.