The 1H NMR spectrum of fluorene has signals at δ 3.8 and δ 7.2-7.7 in a 1:4 ratio. After h...

The 1H NMR spectrum of fluorene has signals at δ 3.8 and δ 7.2-7.7 in a 1:4 ratio. After heating with NaOCH3 in CH3OD at reflux for 15 minutes the signals at δ 7.2-7.7 remained, but the one at δ 3.8 had disappeared. Suggest an explanation and write a mechanism for this observation.

Fluorene