An amine R₂NH is typically more than 20 pK_a units more acidic than the hydrogens of the carbon analog, R₂CH₂ (the element effect; Sec. 3.6A). However, the acidities of 1,3-cyclopentadiene and pyrrole are an exception.

Use the theory of aromaticity to explain this exception.

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H H 1,3-cyclopentadiene pK₂ = 15 -Z: H pyrrole pk₂ = 17