Acidity of Methoxybenzene and Methyl Benzene
Methoxybenzene and methyl benzene are both aromatic compounds. However, the presence of a methoxy group (-OCH3) in methoxybenzene and the absence of such a group in methyl benzene affects their acidity.
Electron-Withdrawing Nature of Methoxy Group
The methoxy group in methoxybenzene is an electron-withdrawing group, meaning it can withdraw electrons from the benzene ring. This is due to the electronegativity of oxygen, which is higher than that of carbon. The presence of the methoxy group results in a decrease in electron density in the ring, making it less basic and more acidic.
Effect on Resonance Stabilization
The methoxy group in methoxybenzene is also a meta-directing group, meaning it directs incoming groups to the meta-position. This affects the resonance stabilization of the benzene ring. The resonance structures that result from the methoxy group being in the meta-position cause a greater degree of delocalization of electrons. This leads to a more stable intermediate, which makes the hydrogens on the ring more acidic.
Comparison of Acidity
Since the methoxy group in methoxybenzene is an electron-withdrawing group and a meta-directing group, it makes the compound more acidic than methyl benzene. As a result, methoxybenzene has a lower pKa value than methyl benzene.
Conclusion
In conclusion, the presence of a methoxy group in methoxybenzene makes it more acidic than methyl benzene. The methoxy group's electron-withdrawing and meta-directing nature decreases electron density and increases resonance stabilization, respectively, leading to a more acidic compound.