Question

The conversion of ethyl bromide to ethyl iodide using sodium iodide and dry acetone, this reaction is known as:
A. Swarts reaction
B. Finkelstein reaction
C. Sandmeyer reaction
D. Stephen reaction

Answer 1

Hint: Swarts reaction is most often used to get alkyl fluorides in the presence of antimony salts, Finkelstein reaction is used to get alkyl iodide from another alkyl chloride or bromide, Sandmeyer reaction is used to produce aryl halides and Stephen reaction is used for the preparation of aldehydes. Ethyl group belongs to the alkyl group.

Complete Step by step answer:The conversion of ethyl bromide $\left( {{C_2}{H_5}Br} \right)$ to ethyl iodide $\left( {{C_2}{H_5}I} \right)$ using sodium iodide $\left( {NaI} \right)$ and dry acetone $\left( {{C_3}{H_8}O} \right)$ i.e., it is a kind of replacement reaction in which bromine is being replaced by iodine. This
Now, we’ll go according to the options:
Swarts reaction: This is a type of reaction in organic compounds in which one or more chlorine atoms are being replaced by the fluorine atoms through the action of antimony trifluoride $\left( {Sb{F_3}} \right)$ i.e.,it is generally used to get alkyl fluorides from alkyl chlorides or alkyl bromides.
Finkelstein reaction: This reaction is named after the German chemist Hans Finkelstein that involves the exchange of one halogen atom with another. It converts alkyl chloride or alkyl bromide to an alkyl iodide by treatment with a solution of sodium iodide in acetone.
Sandmeyer reaction: This is a chemical reaction which is used to synthesize aryl halides from aryl diazonium salts using copper salts as reagents or catalysts. Aryl halide is an aromatic compound in which one or more hydrogen atoms directly bonded to an aromatic ring is being replaced by a halide.
Stephen reaction: This reaction involves the preparation of aldehydes $\left( {R - CHO} \right)$ from nitriles$\left( {R - CN} \right)$ using tin $\left( {II} \right)$ chloride , hydrochloric acid and quenching the resulting salt with water. During this process, ammonium chloride is also formed and R represents the alkyl group.
Thus, it is clear from the above four definitions that the conversion given in the question in which ethyl iodide is obtained from ethyl bromide is known as Finkelstein reaction.

Therefore, option B is correct.

Note: Kindly remember or memorize properly all these four types of reaction which would give us the answer of the above question easily. Don’t get confused between Swarts and Finkelstein reaction as both involve the conversion of one alkyl halide to another.