Why are haloalkanes more reactive towards nucleophilic substitution reactions than haloarenes and vinylic halides?

Question 22:Why are haloalkanes more reactive towards nucleophilic substitution reactions than haloarenes and vinylic halides?

The correct answer is – Haloalkanes (alkyl halides) are generally more reactive towards nucleophilic substitution reactions than haloarenes (aryl halides) and vinylic halides (alkenes with a halogen atom attached to a carbon-carbon double bond) due to several factors. Firstly, the carbon-halogen bond in haloalkanes is generally weaker than in haloarenes and vinylic halides, which makes it easier for the halogen atom to dissociate and leave as a halide ion. This makes the reaction more favorable since it involves the formation of a more stable anion (halide ion) compared to the neutral substrate. Secondly, haloalkanes have a larger and more polarizable carbon-halogen bond compared to haloarenes and vinylic halides. This makes the carbon atom in the haloalkane more electrophilic, meaning it has a greater tendency to attract nucleophiles. In contrast, the carbon-halogen bond in haloarenes and vinylic halides is more stable and less polarizable, resulting in a less electrophilic carbon atom. Lastly, haloarenes and vinylic halides have a more rigid and planar structure compared to haloalkanes, which makes it difficult for a nucleophile to approach the carbon atom and initiate a substitution reaction. The aromatic ring in haloarenes and the double bond in vinylic halides also provide a certain degree of stability that resists nucleophilic attack. Overall, the combination of weaker and more polarizable carbon-halogen bonds and a more flexible structure makes haloalkanes more reactive towards nucleophilic substitution reactions than haloarenes and vinylic halides.