Editing Cyclopentadiene (section)

===Deprotonation===
{{main|Cyclopentadienyl anion}}
The compound is unusually [[acid]]ic (p''K''<sub>a</sub>&nbsp;= 16) for a [[hydrocarbon]], a fact explained by the high stability of the [[aromatic]] cyclopentadienyl anion, {{chem|C|5|H|5|−}}. [[Deprotonation]] can be achieved with a variety of bases, typically [[sodium hydride]], sodium metal, and [[butyl lithium]]. Salts of this anion are commercially available, including [[sodium cyclopentadienide]] and [[lithium cyclopentadienide]]. They are used to prepare [[cyclopentadienyl complex]]es.