객관식
Which of the following best describes the expected number of distinct proton environments (signals) in the compound butyl acetate in its NMR spectrum?
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15. Analytical Techniques:IR, NMR, Mass Spect
NMR Spectroscopy
객관식
Which of the following best describes the expected NMR spectrum of acetophenone () in terms of the number of distinct proton signals?
A
Four distinct signals: one for the methyl group, two for the aromatic protons (due to symmetry), and one for the solvent
B
Two distinct signals: one for all protons in the molecule and one for the solvent
C
Three distinct signals: one for the aromatic protons, one for the methyl group, and one for the methylene group
D
Three distinct signals: one for the methyl group, two for the aromatic protons (due to symmetry)
검증된 단계별 안내1
Identify the different types of protons present in acetophenone (C\_6H\_5COCH\_3). There are aromatic protons on the benzene ring and methyl protons attached to the carbonyl group.
Analyze the symmetry of the aromatic ring. Because the carbonyl group is attached to the ring, the aromatic protons are not all equivalent, but due to symmetry, some sets of protons are equivalent, leading to fewer distinct signals.
Count the number of distinct proton environments: the methyl group protons (CH\_3) form one environment, and the aromatic protons split into two distinct environments due to their positions relative to the carbonyl substituent.
Consider the solvent peak separately, as it is not part of the molecule but often appears in the NMR spectrum and can be identified distinctly.
Conclude that the expected \( ^1H \) NMR spectrum of acetophenone will show three distinct signals corresponding to the methyl protons and two sets of aromatic protons, excluding the solvent peak.
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