Alkyl Halides - Result Question 20

20. The synthesis of alkyl fluorides is best accomplished by

(2015 Main)

(a) free radical fluorination

(b) Sandmeyer’s reaction

(c) Finkelstein reaction

(d) Swarts reaction

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Answer:

Correct Answer: 20. (d)

Solution:

  1. Alkyl fluorides can be prepared by action of mercurous fluoride or antimony trifluorides (inorganic fluorides) on corresponding alkyl halide. This reaction is known as Swarts reaction.

$ CH _3 Br+AgF \longrightarrow \underset{\text{Methyl fluoride}}{CH _3 F}+AgBr $

But, when aciton of $NaI /$ acetone takes place on alkyl chloride of bromide, alkyl iodide forms. This reaction is called ‘Finkelstein reaction’

$ C _2 H _5 Cl \xrightarrow[\text { acetone }]{NaI} C _2 H _5 I+NaCl $

Free redical fluorination is highly explosive reaction, so not preferred for the preparation of fluoride.