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Consider a 1H NMR spectrum in which a quartet and a doublet appeared at 9.72 and 2.40 ppm, respectively. Which of the following compounds is the most probable one:
- a)CH3COCH3
- b)CH3CH2CHO
- c)CH3CHO
- d)CH3CH2CH2OH
Correct answer is option 'C'. Can you explain this answer?
Most Upvoted Answer
Consider a 1H NMR spectrum in which a quartet and a doublet appeared a...
Explanation:
The quartet at 9.72 ppm indicates the presence of a group of 3 equivalent protons, which are coupled to a proton in a neighboring carbon atom. The coupling constant, J, can be determined using the formula:
J = Δν / (n + 1)
where Δν is the distance between the peaks in the quartet (in Hz) and n is the number of neighboring protons (in this case, n = 1).
J = (9.72 - 9.60) / (1 + 1) = 0.06 Hz
The doublet at 2.40 ppm indicates the presence of a group of 3 equivalent protons, which are not coupled to any neighboring protons.
Reasoning:
Based on the NMR data, the most probable compound is CH3CHO (acetaldehyde). This is because the quartet at 9.72 ppm corresponds to the protons on the aldehyde carbon, which is directly attached to the methyl group. The doublet at 2.40 ppm corresponds to the methyl group itself. The chemical shift of the aldehyde carbon is consistent with that of other aldehydes, and the absence of a coupling between the aldehyde protons and any neighboring protons indicates that they are not in close proximity to any other protons in the molecule. This is consistent with the structure of acetaldehyde. The other compounds listed (acetone, propanal, and 1-propanol) do not have the same NMR data as CH3CHO and can be eliminated as possibilities.
The quartet at 9.72 ppm indicates the presence of a group of 3 equivalent protons, which are coupled to a proton in a neighboring carbon atom. The coupling constant, J, can be determined using the formula:
J = Δν / (n + 1)
where Δν is the distance between the peaks in the quartet (in Hz) and n is the number of neighboring protons (in this case, n = 1).
J = (9.72 - 9.60) / (1 + 1) = 0.06 Hz
The doublet at 2.40 ppm indicates the presence of a group of 3 equivalent protons, which are not coupled to any neighboring protons.
Reasoning:
Based on the NMR data, the most probable compound is CH3CHO (acetaldehyde). This is because the quartet at 9.72 ppm corresponds to the protons on the aldehyde carbon, which is directly attached to the methyl group. The doublet at 2.40 ppm corresponds to the methyl group itself. The chemical shift of the aldehyde carbon is consistent with that of other aldehydes, and the absence of a coupling between the aldehyde protons and any neighboring protons indicates that they are not in close proximity to any other protons in the molecule. This is consistent with the structure of acetaldehyde. The other compounds listed (acetone, propanal, and 1-propanol) do not have the same NMR data as CH3CHO and can be eliminated as possibilities.
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Consider a 1H NMR spectrum in which a quartet and a doublet appeared a...
3 hydrogen (example : ch3) gives quartet
1 hydrogen (example: cho) gives doublet
1 hydrogen (example: cho) gives doublet
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Consider a 1H NMR spectrum in which a quartet and a doublet appeared at 9.72 and 2.40 ppm, respectively. Which of the following compounds is the most probable one:a)CH3COCH3b)CH3CH2CHOc)CH3CHOd)CH3CH2CH2OHCorrect answer is option 'C'. Can you explain this answer? for Chemistry 2025 is part of Chemistry preparation. The Question and answers have been prepared according to the Chemistry exam syllabus. Information about Consider a 1H NMR spectrum in which a quartet and a doublet appeared at 9.72 and 2.40 ppm, respectively. Which of the following compounds is the most probable one:a)CH3COCH3b)CH3CH2CHOc)CH3CHOd)CH3CH2CH2OHCorrect answer is option 'C'. Can you explain this answer? covers all topics & solutions for Chemistry 2025 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for Consider a 1H NMR spectrum in which a quartet and a doublet appeared at 9.72 and 2.40 ppm, respectively. Which of the following compounds is the most probable one:a)CH3COCH3b)CH3CH2CHOc)CH3CHOd)CH3CH2CH2OHCorrect answer is option 'C'. Can you explain this answer?.
Consider a 1H NMR spectrum in which a quartet and a doublet appeared at 9.72 and 2.40 ppm, respectively. Which of the following compounds is the most probable one:a)CH3COCH3b)CH3CH2CHOc)CH3CHOd)CH3CH2CH2OHCorrect answer is option 'C'. Can you explain this answer? for Chemistry 2025 is part of Chemistry preparation. The Question and answers have been prepared according to the Chemistry exam syllabus. Information about Consider a 1H NMR spectrum in which a quartet and a doublet appeared at 9.72 and 2.40 ppm, respectively. Which of the following compounds is the most probable one:a)CH3COCH3b)CH3CH2CHOc)CH3CHOd)CH3CH2CH2OHCorrect answer is option 'C'. Can you explain this answer? covers all topics & solutions for Chemistry 2025 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for Consider a 1H NMR spectrum in which a quartet and a doublet appeared at 9.72 and 2.40 ppm, respectively. Which of the following compounds is the most probable one:a)CH3COCH3b)CH3CH2CHOc)CH3CHOd)CH3CH2CH2OHCorrect answer is option 'C'. Can you explain this answer?.
Solutions for Consider a 1H NMR spectrum in which a quartet and a doublet appeared at 9.72 and 2.40 ppm, respectively. Which of the following compounds is the most probable one:a)CH3COCH3b)CH3CH2CHOc)CH3CHOd)CH3CH2CH2OHCorrect answer is option 'C'. Can you explain this answer? in English & in Hindi are available as part of our courses for Chemistry.
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