Understanding the Concept:
Sandmeyer's reaction utilizes copper(I) salts ($\text{CuCl}$, $\text{CuBr}$, $\text{CuCN}$) as radical catalysts to replace the diazonium group on an aromatic ring.
Fluorobenzene cannot be synthesized using a standard Sandmeyer procedure because copper(I) fluoride ($\text{CuF}$) is unstable and difficult to prepare, not due to endothermic constraints. Instead, fluorobenzene is synthesized via the Balz-Schiemann reaction by precipitating benzenediazonium fluoroborate ($\text{ArN}_2^+\text{BF}_4^-$) and thermally decomposing it.
Step 1: Evaluate Statement (B).
Statement (B) correctly notes that fluorobenzene cannot be prepared via a standard Sandmeyer reaction, but its explanation regarding highly endothermic constraints is incorrect. The limitation stems from the lack of a viable copper(I) catalyst pathway. Thus, statement (B) is incorrect, making it the targeted selection choice.
Step 2: Verify why the other options are correct statements.
Statement (A) is correct: Reducing acetoxime ($\text{(CH}_3)_2\text{C}=\text{NOH}$) with sodium and ethanol ($\text{Na/EtOH}$, Bouveault-Blanc reduction conditions) converts the oxime function into a primary amine, yielding propan-2-amine.
Statement (C) is correct: In an aqueous medium, aliphatic primary amines are more basic than aromatic tertiary or primary amines because resonance delocalizes the lone pair of the nitrogen atom into the benzene ring.
Statement (D) is correct: Gabriel Phthalimide synthesis relies on an $\text{S}_{\text{N}}2$ displacement of an alkyl halide by the phthalimide anion. Aryl halides do not undergo nucleophilic substitution under standard conditions, meaning aniline cannot be prepared via this pathway.