In contrast to the reaction (i), reaction (ii) predicts the formation of a thioether. Explain this phenomenon.

Determine the products of the following reactions.

a. CH₃Br + CH₃CH₂N(CH₃)₂

b. CH₃Br + CH₃CH₂S⁻

Allyl chloride is an important industrial compound. Large quantities of allyl chloride are used to produce epichlorohydrin, a precursor to many epoxy resins. Allyl chloride reacts with many nucleophiles to give nucleophilic substitution reactions. An alkyl halide that is similar in structure to allyl chloride is propyl chloride. If both of these compounds react with sodium methoxide, which is less likely to be consumed first?

For which of these reactions would the rate of formation of the carbocation be higher?

Which of the following structures has a better leaving group? Justify your answer.

For the two pairs of anions given below, state which one in each pair is a better leaving group.

a. ⁻NH₂ and F⁻

b. Br⁻ and Cl⁻

The synthesis of 2,3-dihydrobenzo[b][1,4]dioxine-2,3-dicarboxylic acid is illustrated here:

(a) Illustrate the mechanism by which A is converted to B. 

(b) Which is formed faster between A and B?

Consider the following pair of compounds: 

(i) 1-bromo-2-methylpropane or 3-bromopentane

(ii) 2-chloropentane or 1-chloro-3-methylbutane

(iii) 1-fluoro-2-methylbutane or 2-fluoro-3-methylbutane

Identify the better S_N2 substrate.

Consider the S_N2 reaction of 1-chloro-3-methylpentane with a large excess of ammonia (NH₃). Draw the reactants, the transition states, and the products.

Arrange the following compounds in decreasing order of their reactivity towards S _N1 reactions.

Benzyl iodide can either react via S_N2 or S_N1 substitution mechanism. Since Benzyl iodide is a 1* alkyl halide it is expected to react via S_N2 and not S_N1.

Draw the mechanism for the S_N1 substitution reaction and determine how this primary halide undergoes S_N1 reactions.

Consider the following S_N1 reaction:

(i) Provide the reaction mechanism. 

(ii) Identify the role (acid/base/nucleophile/electrophile) of 1-propanol in the reaction. 

(iii) Identify the functional group formed in the product.

Which of the substitution reactions below occurs at a faster rate? Why?

Explain why, regardless of the base utilized, the following alkyl halide does not undergo a substitution reaction. 

Consider the following reaction: 

1-chloro-1,3,4-trimethylcyclopentane + propan-1-ol →

Is its mechanism predominantly first order (S_N1) or second order (S_N2)? What is the expected substitution product? (Recall: The strength of the nucleophile (or base) usually dictates the order of the reaction. Weak nucleophiles often react by unimolecular first-order pathways, while strong nucleophiles promote bimolecular second-order reactions. Also, S_N1 is unlikely with 1° halides unless they are resonance-stabilized, while S_N2 is unlikely with 3° halides.)