Show how you would accomplish the following synthetic conversions. You may use any additional reagents and solvents you need.
(d)

검증된 단계별 안내

Step 1: Begin with the starting material, benzaldehyde (PhCHO). To introduce the alkyne functionality, perform a nucleophilic addition reaction using ethynylmagnesium bromide (C≡CHMgBr), a Grignard reagent. This will add the ethynyl group to the carbonyl carbon, forming an alcohol intermediate.

Step 2: After the addition of the ethynyl group, the intermediate will be a secondary alcohol with the structure PhCH(OH)C≡CH. This step involves hydrolysis of the Grignard addition product using water or dilute acid.

Step 3: To extend the alkyne chain, perform an alkylation reaction. Deprotonate the terminal alkyne (C≡CH) using a strong base such as sodium amide (NaNH2) to generate the acetylide anion (C≡C⁻). Then, react this anion with ethyl bromide (CH3CH2Br) to introduce the ethyl group, forming PhCH(OH)C≡CCH2CH3.

Step 4: Ensure stereochemical integrity and verify the product structure. The hydroxyl group remains intact, and the alkyne chain is extended as desired. Use spectroscopic techniques like NMR or IR to confirm the presence of the alcohol and alkyne functionalities.

Step 5: Purify the final product using appropriate methods such as column chromatography or recrystallization to isolate PhCH(OH)C≡CCH2CH3 in high yield and purity.

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주요 개념

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

Aldol Condensation

Aldol condensation is a key reaction in organic chemistry where aldehydes or ketones with alpha-hydrogens react in the presence of a base to form beta-hydroxy aldehydes or ketones. This reaction can lead to the formation of larger carbon skeletons through the formation of carbon-carbon bonds, which is essential for synthesizing complex molecules.

Alkyne Formation

The formation of alkynes typically involves the elimination of small molecules from alkenes or the dehydrohalogenation of alkyl halides. In this context, the conversion of a compound to an alkyne requires specific reagents, such as strong bases, to facilitate the removal of hydrogen or halogen atoms, resulting in the formation of a triple bond.

Reagent Selection

Choosing the appropriate reagents and solvents is crucial in organic synthesis to ensure the desired reaction occurs efficiently. For the conversion of PhCHO to the target compound, reagents such as sodium hydroxide for aldol condensation and strong bases like sodium amide for alkyne formation may be necessary to achieve the desired transformations while controlling reaction conditions.

Show how you would accomplish the following synthetic conversions. You may use any additional reagents and solvents you need.(d)