Q.In an experiment, ethyl iodide in ether is allowed to stand over magnesium pieces. Magnesium dissolves and a product is formed. a) Name the product and write the equation for the reaction. b) Why should all the reagents used in the reaction be dry? Explain. c) How is acetone prepared from the product obtained in the experiment?

Step 1 (a). Ethyl iodide, C2H5I, dissolved in ether and left standing over magnesium metal reacts as the metal dissolves: C2H5I + Mg (dry ether) gives C2H5MgI, ethylmagnesium iodide -- the Grignard reagent.

Step 2 (b). Every reagent and every piece of glassware must be rigorously dry because RMgX is both a strong base and a strong nucleophile: any trace of water (or an alcohol, or an amine) instantly protonates it, converting the valuable Grignard reagent into the synthetically useless alkane (here, ethane) before it can be used for the intended synthesis -- exactly the 'Preparation of Alkanes' reaction from the reagent's own synthetic-uses list. …

For (a)/(b), apply the standard Grignard preparation and anhydrous-condition reasoning directly to ethyl iodide. For (c), apply the acid-chloride-to-ketone rule …

• For (c), using excess Grignard reagent with the acid chloride -- that gives a TERTIARY alcohol, not the ketone; isolating a ketone specifically requires limiting the Grignard reagent to one equivalent (or othe …