The following reaction method [figure] is not suitable for the preparation of the corresponding haloarene products, due to high reactivity of halogen, when X is :
- F
- I
- Cl
- Br
Answer
(1) F
Solution
Fluorine is so reactive that its reaction with arenes is violent and cannot be controlled, so aryl fluorides are not prepared by direct halogenation (they are made from diazonium salts by the Balz–Schiemann reaction).
(Iodination is reversible and needs an oxidising agent such as HNO3 or HIO4, but that is due to the low reactivity of iodine.)
Answer: (1)