Question

The alkyl halide is converted into an alcohol by

• A. addition
• B. substitution
• C. dehydrohalogenation
• D. elimination

Answer 1

The Correct Option is B

To understand how an alkyl halide is converted into an alcohol, we need to examine the nature of the reactions available in the options provided. The conversion of an alkyl halide to an alcohol involves a substitution reaction.

1. Substitution Reaction: In this type of reaction, a nucleophile (in this case, a hydroxyl ion, \text{OH}^-\)) replaces a leaving group (in this case, a halide ion) on the alkyl group. The general reaction can be depicted as:

\[\text{R-X} + \text{OH}^- \rightarrow \text{R-OH} + \text{X}^-\]

Where:

• \text{R-X} is the alkyl halide.
• \text{OH}^-\) is the hydroxide ion.
• \text{R-OH} is the resulting alcohol.

This process is known as nucleophilic substitution or often simply substitution, such as in the case of the S_N1 or S_N2 mechanisms.

Now, let's briefly discuss why other options are incorrect:

• Addition: Typically involves the addition of atoms or groups to a molecule without displacing any existing atoms, not suitable for converting alkyl halides to alcohols.
• Dehydrohalogenation: This is an elimination reaction where a hydrogen halide is removed from a molecule, leading to the formation of alkenes, not alcohols.
• Elimination: Generally involves the removal of atoms leading to the formation of double or triple bonds, rather than substitution of a halide with an alcohol group.

Therefore, the correct answer is substitution, where the halide ion is replaced by a hydroxyl group to form an alcohol.