For each reaction, decide whether substitution or elimination (or both) is possible, and predict the products you expect. Label the major products.
c. chlorocyclohexane+NaOCH₃ in CH₃OH
d. chlorocyclohexane + NaOC(CH₃)₃ in (CH₃)₃COH

Verified step by step guidance

1. Step 1: Analyze the substrate (chlorocyclohexane) in both reactions. Chlorocyclohexane is a secondary alkyl halide, which can undergo both substitution (SN1 or SN2) and elimination (E1 or E2) reactions depending on the reaction conditions.
2. Step 2: For reaction (c) with NaOCH3 in CH3OH, identify the base/nucleophile and solvent. NaOCH3 is a strong nucleophile and a strong base, while CH3OH is a polar protic solvent. This setup favors both SN2 and E2 mechanisms. Predict the products: (1) For SN2, substitution of the chlorine atom with -OCH3 will occur. (2) For E2, elimination will lead to the formation of a cyclohexene product. The major product will depend on the reaction conditions, but E2 is often favored with strong bases.
3. Step 3: For reaction (d) with NaOC(CH3)3 in (CH3)3COH, identify the base/nucleophile and solvent. NaOC(CH3)3 is a bulky, strong base, and (CH3)3COH is a polar protic solvent. Bulky bases favor elimination (E2) over substitution due to steric hindrance. Predict the product: elimination will lead to the formation of cyclohexene as the major product.
4. Step 4: Consider the regioselectivity of the elimination reactions. In both cases, the elimination will follow Zaitsev's rule, where the more substituted alkene is the major product. For cyclohexane derivatives, this typically results in a single product (cyclohexene) due to the symmetry of the ring.
5. Step 5: Summarize the major products for each reaction. For reaction (c), both substitution (SN2) and elimination (E2) products are possible, with the major product depending on the reaction conditions. For reaction (d), elimination (E2) is the dominant pathway, and cyclohexene is the major product.

Key Concepts

Nucleophilic Substitution Reactions

Nucleophilic substitution reactions involve the replacement of a leaving group (like a halide) by a nucleophile. In this context, the nucleophile is the alkoxide ion (NaOCH3 or NaOC(CH3)3). Understanding the mechanism (SN1 or SN2) is crucial, as it influences the reaction pathway and the structure of the products formed.

Elimination Reactions

Elimination reactions involve the removal of a leaving group and a hydrogen atom, resulting in the formation of a double bond. The two main types are E1 and E2 mechanisms. The choice between substitution and elimination often depends on factors such as the strength of the base, the structure of the substrate, and the reaction conditions.

Reaction Conditions and Solvent Effects

The solvent and reaction conditions significantly influence whether substitution or elimination occurs. Polar protic solvents favor SN1 and E1 mechanisms, while polar aprotic solvents favor SN2 and E2 mechanisms. In the given reactions, the choice of methanol and tert-butanol as solvents will affect the reactivity and the predominant pathway taken by the nucleophile.