Question 1

Why is the thionyl chloride method preferred for preparing alkyl chloride from alcohols?

Accepted Answer

Because the reaction produces only alkyl chloride and two gases (SO$$_2$$ and HCl) that escape, leaving pure alkyl chloride.

Question 2

Which of the following best explains why o-nitrophenol is more steam volatile than p-nitrophenol?

Accepted Answer

o-Nitrophenol forms intramolecular hydrogen bonds, reducing its boiling point.

Question 3

When t-butyl chloride is heated with sodium methoxide, why does it give 2-methylpropene instead of t-butyl methyl ether?

Accepted Answer

Because the t-butyl carbocation is stabilized, favoring elimination (E2) over substitution (SN2).

Question 4

Why is the boiling point of ethanol higher than that of methoxymethane?

Accepted Answer

Ethanol forms strong intermolecular hydrogen bonds, while methoxymethane is held by dipole-dipole interactions.

Question 5

In the reaction of (CH$$_3$$)$$_3$$COC$$_2H$_5$$ with HI, why is CH$$_3I $$the main product instead of C$$_2H$_5I$$?

Accepted Answer

Because the SN1 mechanism is favored and the tertiary carbocation is more stable.

Question 6

Why are lower alcohols water soluble while higher alcohols are water insoluble?

Accepted Answer

Lower alcohols can form hydrogen bonds with water, but in higher alcohols, the large hydrocarbon part makes hydrogen bonding insufficient.

Question 7

Why does phenol not give protonation reactions readily?

Accepted Answer

The lone pair of electrons on the oxygen atom is delocalized over the benzene ring due to resonance, making it less available for protonation.

Question 8

Which is more acidic: 2-chloroethanol or ethanol, and why?

Accepted Answer

2-chloroethanol, because the electron-withdrawing effect of Cl decreases electron density on O-H, increasing acidity.

Question 9

Why is the C-O-H bond angle in alcohols slightly less than the tetrahedral angle (109.5$$^\circ$$)?

Accepted Answer

Due to repulsion between the unshared electron pairs of oxygen.

Question 10

In Kolbe's reaction, why is phenoxide ion used instead of phenol when reacting with CO$$_2$$?

Accepted Answer

Phenoxide is more reactive than phenol towards electrophilic aromatic substitution, allowing reaction with weak electrophile CO$$_2.$$

Question 11

Why are aldehydes more reactive than ketones towards nucleophilic reagents?

Accepted Answer

Ketones have two bulky alkyl groups that hinder nucleophile approach and decrease the positive charge on the carbonyl carbon.

Question 12

A patient is exposed to methoxymethane and ethanol vapors. Which compound is expected to have a higher boiling point and why?

Accepted Answer

Ethanol, because it forms strong intermolecular hydrogen bonds.

Question 13

Which of the following statements best explains the increased acidity of 2-chloroethanol compared to ethanol?

Accepted Answer

The electron-withdrawing chlorine atom stabilizes the conjugate base by decreasing electron density on the O-H bond.

Question 14

Which of the following is a correct reason why phenol does not undergo protonation easily?

Accepted Answer

The lone pair on oxygen is delocalized into the benzene ring, reducing its availability for protonation.

Question 15

A chemist wants to prepare pure alkyl chloride from an alcohol. Which method should they use and why?

Accepted Answer

Thionyl chloride method, because the by-products are gases that escape, leaving pure alkyl chloride.

Question 16

Which of the following best explains why t-butyl chloride reacts with sodium methoxide to give 2-methylpropene?

Accepted Answer

The reaction proceeds via elimination (E2) due to the stability of the tertiary carbocation.

Question 17

Which of the following is a reason why aldehydes are more reactive than ketones towards nucleophilic addition?

Accepted Answer

Ketones have two electron-releasing alkyl groups that decrease the positive charge on the carbonyl carbon.

Organic Chemistry Reasoning Questions: Halogen Compounds, Alcohols, Phenols, Aldehydes, Ketones, and Carboxylic Acids

Study Guide - Practice Questions