Which carbon of (a)-(d) of hex-3-en-2-one shows the largest (most downfield) chemical shift in the NMR spectrum?a)C1b)C2c)C4d)C6Correct answer is option 'B'. Can you explain this answer?

Question

Answer

C1 and C6 are the methyl carbons while C2 is a carbonyl and C4 is a vinylic carbon. The carbonyl carbon shows the largest (most downfield) shift of the four, as summarized.

Answer

Chemical Shift in NMR Spectrum of Hex-3-en-2-one
Hex-3-en-2-one is a compound with a carbon-carbon double bond and a carbonyl group. The chemical shift in the NMR spectrum of this compound can be analyzed to determine which carbon atom experiences the largest (most downfield) shift.

Explanation:
- C1: Carbon 1 is directly attached to the carbonyl group, which causes it to experience a deshielding effect, leading to a downfield shift in the NMR spectrum.
- C2: Carbon 2 is part of the carbon-carbon double bond, which also experiences deshielding due to the presence of pi electrons. This results in a significant downfield shift in the NMR spectrum.
- C4: Carbon 4 is further away from the functional groups and is not as affected by deshielding effects, resulting in a smaller chemical shift compared to C1 and C2.
- C6: Carbon 6 is also not directly involved in any functional groups and experiences the least deshielding effect, leading to the smallest chemical shift in the NMR spectrum.
Therefore, in the NMR spectrum of hex-3-en-2-one, carbon 2 (C2) shows the largest (most downfield) chemical shift due to its proximity to the carbon-carbon double bond, which causes significant deshielding effects.

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