Write a balanced equation for each reaction, showing the major product you expect.
(d)

검증된 단계별 안내

Step 1: Identify the type of reaction. The presence of NaOH and heat suggests an elimination reaction (E2 mechanism), where the alkyl halide undergoes dehydrohalogenation to form an alkene.

Step 2: Analyze the structure of the starting material, CH3CH(CH3)C(CH3)2Br. The bromine atom is attached to a tertiary carbon, which is highly favorable for elimination reactions due to steric hindrance.

Step 3: Determine the possible β-hydrogens available for elimination. The β-hydrogens are located on the carbons adjacent to the carbon bonded to the bromine atom. In this case, there are β-hydrogens on the methyl groups and the ethyl group.

Step 4: Apply Zaitsev's rule to predict the major product. Zaitsev's rule states that the most substituted alkene will be the major product. Elimination of a β-hydrogen from the ethyl group will result in the formation of the more substituted alkene.

Step 5: Write the balanced equation for the reaction. The bromine atom is removed, and a double bond is formed between the α-carbon (the carbon bonded to bromine) and the β-carbon (the carbon from which the hydrogen is eliminated). The major product is the more substituted alkene.

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주요 개념

질문에 올바르게 답하기 위해 반드시 이해해야 하는 핵심 개념들은 다음과 같습니다.

Nucleophilic Substitution Reactions

Nucleophilic substitution reactions involve the replacement of a leaving group (like Br) by a nucleophile (like OH- from NaOH). These reactions can proceed via two main mechanisms: SN1, which is unimolecular and involves a carbocation intermediate, and SN2, which is bimolecular and involves a direct attack by the nucleophile. The choice of mechanism depends on factors such as substrate structure and the strength of the nucleophile.

Carbocation Stability

Carbocation stability is crucial in determining the pathway of nucleophilic substitution reactions. Tertiary carbocations are more stable than secondary or primary due to hyperconjugation and inductive effects from surrounding alkyl groups. In the given reaction, the presence of multiple alkyl groups adjacent to the carbocation can favor the SN1 mechanism, leading to the formation of a more stable intermediate before the nucleophile attacks.

Reaction Conditions and Heat

The reaction conditions, including the use of heat, can influence the outcome of nucleophilic substitution reactions. Heating can favor elimination reactions or promote the formation of more stable products. In this case, heating the reaction with NaOH may enhance the likelihood of an SN1 pathway, allowing for the formation of a stable carbocation and subsequent product formation, rather than competing elimination reactions.

Write a balanced equation for each reaction, showing the major product you expect. (d)