Question

Given below are two statements:

Statement - I: Boiling points of alcohols and phenols are higher in comparison to hydrocarbons, ethers, haloalkanes and haloarenes of comparable molecular masses.

Statement - II: Anisole on reaction with ethanoyl chloride in presence of anhydrous $AlCl_3$ gives 2-methoxyacetophenone as a major product.

In the light of the above statements choose the correct answer from the options given below:

• A. Both Statement I and II are true
• B. Both Statement I and II are false
• C. Statement I is true, but Statement II is false
• D. Statement I is false, but Statement II is true

Answer 1

Answer: (C)

Statement I is true, but Statement II is false

Answer 2

Statement - I Analysis:

Alcohols (R-OH) and phenols (Ar-OH) contain a hydroxyl group. The hydrogen atom in the hydroxyl group is directly bonded to a highly electronegative oxygen atom, which allows for the formation of strong intermolecular hydrogen bonds.

In contrast, hydrocarbons are non-polar and exhibit only weak London dispersion forces. Ethers (R-O-R'), haloalkanes (R-X), and haloarenes (Ar-X) are polar but lack a hydrogen atom directly bonded to a highly electronegative atom (like O or N) to form strong intermolecular hydrogen bonds with themselves. They primarily exhibit dipole-dipole interactions and London dispersion forces.

Since hydrogen bonding is a much stronger intermolecular force than dipole-dipole interactions or London dispersion forces, more energy is required to overcome these forces to cause boiling. Consequently, alcohols and phenols have significantly higher boiling points compared to hydrocarbons, ethers, haloalkanes, and haloarenes of comparable molecular masses.

Thus, Statement I is True.

Statement - II Analysis:

The reaction described is a Friedel-Crafts acylation of anisole with ethanoyl chloride in the presence of anhydrous $AlCl_3$.

Anisole (methoxybenzene) has a methoxy group (-OCH$_3$) attached to the benzene ring. The methoxy group is a strong activating group and an ortho-para director due to the +M (mesomeric) effect of the oxygen's lone pair.

The electrophile generated from ethanoyl chloride and anhydrous $AlCl_3$ is the acylium ion (CH$_3$CO$^+$).

When an electrophile attacks an activated benzene ring with an ortho-para directing group, both ortho and para products are formed. However, due to steric hindrance, the para product is generally the major product, especially when the attacking electrophile is somewhat bulky or the directing group itself has some bulk.

For anisole, the ortho product would be 2-methoxyacetophenone, and the para product would be 4-methoxyacetophenone.

Due to steric hindrance at the ortho position by the methoxy group, 4-methoxyacetophenone is formed as the major product, while 2-methoxyacetophenone is the minor product.

Therefore, stating that 2-methoxyacetophenone is the major product is incorrect.

Thus, Statement II is False.

Conclusion:

Statement I is true, but Statement II is false.