A reagent composed of sodium iodide dissolved in acetone is useful in classifying alkyl halides according to their reactivity in an S N 2 reaction. Iodide is an excellent nucleophile, and acetone is an aprotic solvent. Sodium iodide is soluble in acetone, but the corresponding bromides and chlorides are not soluble. Consequently, as bromide ion or chloride ion is produced, the ion precipitates from solution. A reagent composed of silver nitrate dissolved in ethanol is useful in classifying alkyl halides according to their reactivity in an S N 1 reaction.
Nitrate ion is a poor nucleophile and ethanol is a moderately powerful ionizing solvent.
The silver ion, because of its ability to coordinate the leaving halide ion to form a silver halide precipitate, greatly assists the ionization of the alkyl halide. Some compounds used in this experiment, particularly crotyl chloride and benzyl chloride, are powerful lachrymators. Lachrymators cause eye irritation and the formation of tears. The test with these compounds should be preformed in the hood. Required reading Before beginning this experiment, review the chapters dealing with nucleophilic substitution in your lecture textbook.