Question

Fluorination of an aromatic ring is easily accomplished by treating a diazonium salt with \[HB{{F}_{4}}\]. Which of the following conditions is correct about this reaction?
A. \[NaF/Cu\]
B. \[C{{u}_{2}}O/{{H}_{2}}O\]
C. Only Heat
D. \[NaN{{O}_{2}}/Cu\]

Answer 1

Hint: Electrophilic fluorination is the cycle by which fluoride is conveyed to an electron‐donating reactant, for example, an alkene, fragrant ring or carbanion, by a formal 'positive‐fluorine' reagent to frame a carbon–fluorine covalent bond.

Step by step answer: The Balz–Schiemann reaction, which includes diazotization of the essential fragrant amines followed by fluorinative dediazoniation, could be accomplished in preparative scale via conveying the response in, \[PPHF\] in which case the segregation of the generally hazardous middle person diazonium salts isn't needed. This response has been accomplished on a modern scale in a nonstop stream reactor, utilizing \[HB{{F}_{4}}\] rather than \[PPHF\] as the \[HF\] source.
\[HB{{F}_{4}}\] is a moderately more secure reagent because of its simplicity of activity and operational wellbeing. Utilizing this technique, huge amounts of ortho-difluorobenzene could be set up from the reaction of ortho-fluoro aniline and sodium nitrite, in 90% yield; the reaction time for the diazotization went from 4 to 15 s at \[10-{{25}^{\circ }}C\], though the fluorodediazoniation of the confined diazonium salts continues in 1–7 min at \[{{140}^{\circ }}-{{200}^{\circ }}C\].

Hence, the correct option is C. Only Heat.

Additional Information: Fluoroboric acid is corrosive and attacks the skin. It is available commercially as a solution in water and other solvents such as diethyl ether. It is a strong acid with a weakly coordinating, non-oxidizing conjugate base. It is structurally similar to perchloric acid, but lacks the hazards associated with oxidants.

Note: Selective introduction of fluorine into an aromatic ring is often achieved by thermal decomposition of diazonium fluoroborate, which is called the Balz–Schiemann reaction.