7. Substitution Reactions

Using the given starting material, any necessary inorganic reagents and catalysts, and any carbon-containing compounds with no more than three carbons, indicate how each of the following compounds can be prepared:

a.

Suggest a reagent to carry out each of the following conversions to an alcohol.

(a)

Suggest a mechanism for the following substitution reactions.

(a)

Predict the product for the following substitution reactions. Indicate whether each reaction likely proceeds by an S_N1 or S_N2 mechanism.

(a)

When (R)-(1-bromoethyl)benzene is treated with sodium cyanide, a single enantiomer is produced. However, upon treatment of the same molecule with water, a mixture of two enantiomers is obtained.

(a) Explain these results.

(b) Why is only partial racemization sometimes observed?

The following reaction takes place under second-order conditions (strong nucleophile), yet the structure of the product shows rearrangement. Also, the rate of this reaction is several thousand times faster than the rate of substitution of ­hydroxide ion on 2-chlorobutane under similar conditions. Propose a mechanism to explain the enhanced rate and ­rearrangement observed in this unusual reaction. (“Et” is the abbreviation for ethyl.)

Suggest a reagent to carry out each of the following conversions to an alcohol.

(c)

Suggest a mechanism for the following substitution reactions.

(c)

Draw the substitution products for each of the following reactions; if the products can exist as stereoisomers, show what stereoisomers are obtained:

c. benzyl chloride + CH₃CH₂OH

d. allyl chloride + CH₃OH

Which of the following reactions take place more rapidly when the concentration of the nucleophile is increased?

Alkylbenzyldimethyl ammonium chloride is a leave-on skin antiseptic used to treat such things as cuts and cold sores. It is also the antiseptic in many hand sanitizers. It is actually a mixture of compounds that differ in the number of carbons (any even number between 8 and 18) in the alkyl group. Show three different sets of reagents (each set composed of an alkyl chloride and an amine) that can be used to synthesize the alkylbenzyldimethyl ammonium chloride shown here.

Propose a mechanism for the following reaction:

What nucleophiles would form the following compounds as a result of reacting with 1-iodobutane?

a.

b.

What is the major product of each of the following reactions?

b.

Draw the substitution and elimination products.

a.

b.