Classification of Matter A.2 Classification of Organic Compounds (id: dd9965026)

本题目来源于试卷: Classification of Matter A.2 Classification of Organic Compounds，类别为 IB化学

[单选题]
A carboxylic acid has the following structural formu+/+ikcj:8olj wghvl;la. 8 z1j.xjn7o6kpd,n r m +70qwl+vover



The $^1H NMR$ NMR spectrum of the carboxylic acid is measured. Which of the following correctly describes the pattern of signals in the $NMR$ spectrum?

A. Four signals with integrals in the ratio 3:1:1:1
B. Three signals with integrals in the ratio 6:1:1
C. Three signals with integrals in the ratio 3:3:1
D. Two signals with integrals in the ratio 6:1


参考答案:  B


本题详细解析:
Explanation:

The methyl groups are equivalent so produce one signal with integral 6, while the other protons both produce signals with integrals 1.

The student must recognise that all protons are detectable by NMR, including those attached to O atoms, and know how to count proton environments (COOH protons are sometimes too broad to detect due to proton exchange and/or hydrogen bonding, but this point is not covered at IB level).

The question is categorised as hard as several features of the NMR spectrum must be predicted.

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