Show the products of the following acetylide alkylation reactions. [Make sure your product has the correct number of carbons.]
(b)

검증된 단계별 안내

Step 1: Recognize that the reaction involves acetylide alkylation. The starting material is acetylene (H-C≡C-H), which will undergo deprotonation to form an acetylide ion.

Step 2: The first reagent, NaNH₂ (2 equivalents), is a strong base that will deprotonate both hydrogens on the acetylene molecule, forming the acetylide ion (C≡C²⁻). This ion is highly nucleophilic.

Step 3: The second reagent, bromocyclopentane (2 equivalents), is an alkyl halide. The acetylide ion will attack the carbon attached to the bromine in an SN2 reaction, displacing the bromine and forming a new carbon-carbon bond.

Step 4: Since 2 equivalents of bromocyclopentane are used, the acetylide ion will react twice, adding two cyclopentyl groups to the acetylene molecule. This results in a product with two cyclopentyl groups attached to the original triple bond.

Step 5: Verify the final product structure by ensuring the correct number of carbons and connectivity. The product will have a total of 12 carbons: 2 from the acetylene and 10 from the two cyclopentyl groups.

비슷한 문제에 대한 검증된 영상 답변:

이 영상 해법은 위 문제에 도움이 된다고 튜터들이 추천한 것입니다.

주요 개념

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

Acetylide Ion Formation

Acetylide ions are formed by deprotonating terminal alkynes using strong bases like sodium amide (NaNH2). This reaction generates a nucleophilic acetylide ion, which can then participate in nucleophilic substitution reactions with alkyl halides, allowing for the formation of longer carbon chains.

Nucleophilic Substitution Reactions

Nucleophilic substitution reactions involve the replacement of a leaving group (like bromine in the provided reaction) by a nucleophile (the acetylide ion). The mechanism can follow either an SN2 pathway, where the nucleophile attacks the electrophile directly, or an SN1 pathway, which involves the formation of a carbocation intermediate. The choice of mechanism depends on the structure of the substrate and the conditions of the reaction.

Carbon Count in Organic Synthesis

In organic synthesis, it is crucial to account for the number of carbon atoms in the products. The reaction of an acetylide ion with an alkyl halide adds the carbon chain of the halide to the acetylide, thus increasing the total carbon count. Ensuring the correct number of carbons in the final product is essential for maintaining the integrity of the molecular structure and for further synthetic applications.

Show the products of the following acetylide alkylation reactions. [Make sure your product has the correct number of carbons.](b)