The compound shown reacts with two equivalents of potassium metal and each atom accepts one electron to form a planar dianion. How many pi electrons are in the ring of the dianion? Give your answer as an integer.

Numerical answer type, tolerance 0.5.

Answer: 10

The compound shown is cyclooctatetraene with 8 pi electrons. Accepting two electrons gives 10 pi electrons, which is 4n+2 (n = 2), so the planar dianion is aromatic. The answer is 10.

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