Question

Answer the question on the basis of the passage given below:
Alcohols and phenol are formed when a hydrogen atom in a hydrocarbon, aliphatic and aromatic respectively, is replaced by \(-OH\). The substitution of a hydrogen atom in a hydrocarbon by an alkoxy or aryloxy group forms ethers.
Alcohols and phenol consist of two parts, an alkyl/aryl group and a hydroxyl group. The properties of alcohols and phenols are primarily due to the hydroxyl group. The nature of alkyl and aryl groups simply modify these properties. Alcohol react both as nucleophiles and electrophiles whereas in phenols, the reactions that take place on the aromatic ring are electrophilic substitution reactions.
Few compounds are given below (A to D). Arrange them in the increasing order of their boiling points.
(A) Pentan-1-ol
(B) n-Butane
(C) Pentan-1-al
(D) Ethoxyethane
Choose the correct answer from the options given below:

• A. (D)<(B)<(C)<(A)
• B. (B)<(C)<(A)<(D)
• C. (C)<(B)<(A)<(D)
• D. (D)<(B)<(A)<(C)

Hint:

The boiling point of a substance increases with the presence of hydrogen bonding or polar interactions. Alcohols, which can form hydrogen bonds, generally have higher boiling points than hydrocarbons with similar molecular weights.

Answer 1

The Correct Option is A

In this case, the compounds are arranged based on their boiling points. The order of boiling points generally depends on the intermolecular forces present in the compound: - n-Butane (B) has the lowest boiling point as it is a non-polar molecule, experiencing only London dispersion forces. - Ethoxyethane (D) has a higher boiling point due to dipole-dipole interactions and Van der Waals forces. - Pentan-1-al (C) has even higher boiling points due to hydrogen bonding and dipole-dipole interactions present in aldehydes. - Pentan-1-ol (A) has the highest boiling point because of hydrogen bonding between the hydroxyl group of the alcohol.
Thus, the correct increasing order of boiling points is: \[ \text{(D)<(B)<(C)<(A)} \]
Reactions:
In Pentan-1-ol, the reaction of an alcohol with an acid to form an ester is: \[ \text{R-OH} + \text{R'-COOH} \rightarrow \text{R-COOR'} + \text{H}_2\text{O} \quad \text{(Esterification)} \] For Pentan-1-al, an oxidation reaction occurs, as shown: \[ \text{R-CHO} + \text{[O]} \rightarrow \text{R-COOH} \quad \text{(Oxidation of Aldehyde to Carboxylic Acid)} \]