Arrange the following compounds in increasing order of C – OH bond length:
Question:

Arrange the following compounds in increasing order of $\mathrm{C}$ – OH bond length: methanol, phenol, $p$-ethoxyphenol

1. methanol $<p$-ethoxyphenol $<$ phenol

2. phenol $<$ methanol $<p$-ethoxyphenol

3. phenol $<p$-ethoxyphenol $<$ methanol

4. methanol $<$ phenol $<p$-ethoxyphenol

Correct Option:

Solution:

Resonance is a deciding factor to determine the order of bond length in given compounds. Phenol exhibits least $\mathrm{C}-\mathrm{OH}$ bond length due to resonance whereas methanol will show maximum bond length due to lack of resonance and $p$-ethoxyphenol will have some intermediate value of bond length.