Nucleophilic Substitution Reactions of Alkyl Halides

Purpose:

Experiment will investigate the ease with which the different alkyl halides leave in one of the substitution reactions by exploring leaving groups from each reaction. The results of this technique will be determined if the reaction is biomolecular and unimolecular.

SN2

occur in a one step reaction, depend on the concentration of both the nucleophile and the halide. Occur with inversion of configuration to give a product of the opposite chirality from the starting material. Iodide is hte best leaving group as well as the best Nu.

3<2<1

SN1

occur in a two step reaction, which is slow step, depends only on the concentration of the halide.

3>2>1>CH3>Vinyl

It is favored in low concentration

High polarity favors SN1

Carbocation

a carbocation is often formed a reactive intermediate in these reactions.

Temperature

as the temp increases the kinetic energy of the molecules increases, causing a greater rate of reaction.

Silver Nitrate Solution

This weakens the bond of carbon-halogen, because and insoluble silver halide has formed, promoting an SN1 Rx of the alkyl halide.

Sodium Iodide

Iodide is a great Nu and promotes and SN2 Rxm and its nonpolar.

What would be the effect of carrying out the sodium iodide in acetone reaction with the alkyl halides using iodide solution half as concentrated

If iodide solution is half concentrated then the rate will also be halved

The addition of sodium or potassium iodide catalyzes many SN2 rx of the alkyl chlorides or bromides. Explain

The reason sodium or potassium iodide help this rx is because positively charged sodium and potassium will aid in the leaving process of the LG this making it easie for the Nu to attack and replace LG.