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The mass spectrum of unknown compound A shows a molecular
Chapter 12, Problem 69SP(choose chapter or problem)
The mass spectrum of unknown compound A shows a molecular ion at 𝑚/𝑧 116 and prominent peaks at 𝑚/𝑧 87 and 𝑚/𝑧 101. Its UV spectrum shows no maximum above 200 nm. The IR and NMR spectra of A follow. When A is washed with dilute aqueous acid, extracted into dichloromethane, and the solvent evaporated, it gives a product B. B shows a strong carbonyl
signal at \(1715 \mathrm{~cm}^{-1}\) in the IR spectrum and a weak maximum at \(274 \mathrm{~mm}(\mathrm{E}=16)\) in the UV spectrum. The mass spectrum of B shows a molecular ion of 𝑚/𝑧 72. Determine the structures of A and B, and show the fragmentation to account for the peaks at 𝑚/𝑧 87 and 101.
Equation transcription:
Text transcription:
1715{~cm}^{-1}
274{~mm}({E}=16)
Questions & Answers
QUESTION:
The mass spectrum of unknown compound A shows a molecular ion at 𝑚/𝑧 116 and prominent peaks at 𝑚/𝑧 87 and 𝑚/𝑧 101. Its UV spectrum shows no maximum above 200 nm. The IR and NMR spectra of A follow. When A is washed with dilute aqueous acid, extracted into dichloromethane, and the solvent evaporated, it gives a product B. B shows a strong carbonyl
signal at \(1715 \mathrm{~cm}^{-1}\) in the IR spectrum and a weak maximum at \(274 \mathrm{~mm}(\mathrm{E}=16)\) in the UV spectrum. The mass spectrum of B shows a molecular ion of 𝑚/𝑧 72. Determine the structures of A and B, and show the fragmentation to account for the peaks at 𝑚/𝑧 87 and 101.
Equation transcription:
Text transcription:
1715{~cm}^{-1}
274{~mm}({E}=16)
ANSWER:Solution 69SP
(a) By6 observing the spectra given (I.R) the carbonyl group in A has been protected by the protecting group like ethylene glycol. The spectra (I.R) doesn’t show carbonyl absorption but the hydrolysis of compound A gives carbonyl compound B for that the compound A should contain carbonyl group.