Chapter 14, Problem 34P

The $\text{H}\text{ NMR}$ spectrum of fluorene has signals at $\text{δ 3}\text{.8}$ and $\text{δ }7.2–7.7$ in a $1:4$ ratio. After heating with ${\text{NaOCH}}_{\text{3}}$ in ${\text{CH}}_{\text{3}}\text{OD}$ at reflux for $15$ minutes the signals at $\text{δ }7.2–7.7$ remained, but the one at $\delta 3.8$ had disappeared. Suggest an explanation and write a mechanism for this observation.