Question
Question: Fluorination of an aromatic ring is easily accomplished by treating a diazonium salt with \[HB{{F}_{...
Fluorination of an aromatic ring is easily accomplished by treating a diazonium salt with HBF4. Which of the following conditions is correct about this reaction?
A. NaF/Cu
B. Cu2O/H2O
C. Only Heat
D. NaNO2/Cu
Solution
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 HBF4 rather than PPHF as the HF source.
HBF4 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∘C, though the fluorodediazoniation of the confined diazonium salts continues in 1–7 min at 140∘−200∘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.