NMR spectroscopyEdexcel International A Level Chemistry: Flashcards

What these 13 flashcards ask

What is TMS and why is it used as a standard?
What does the number of peaks in a ¹³C NMR spectrum tell you?
How many ¹³C peaks does 2-methylpropan-2-ol give?
Approximate ¹³C chemical shift range for C=O in ketones and aldehydes?
What does the number of peaks in ¹H NMR tell you?
What does the area under a ¹H NMR peak show?
What causes deshielding of a proton?
State the n + 1 rule.
What splitting pattern does an ethyl group show?
What splitting does the CH₃ of an isopropyl group, –CH(CH₃)₂, show?
What are the area ratios for ethanol?
Why is a solvent with no hydrogen atoms used in ¹H NMR?
Name the peak types for n = 0, 1, 2, 3, 4, 5, 6.

Exam questions on NMR spectroscopy

Three structural isomers of formula C₄H₁₀O are examined by ¹³C NMR spectroscopy: butan-1-ol, butan-2-ol and 2-methylpropan-2-ol.
Explain why the ¹³C NMR spectrum of 2-methylpropan-2-ol, (CH₃)₃COH, has only two peaks even though the molecule has four carbon atoms.2 marks
The ¹H NMR spectrum of ethyl ethanoate, CH₃COOCH₂CH₃, is recorded in a solvent that contains no hydrogen atoms, using tetramethylsilane (TMS) as a reference standard.
Deduce the splitting patterns of the signals from the CH₂ group and from the CH₃ of the ethyl group in ethyl ethanoate, explaining your answers.2 marks
Compound Z has the molecular formula C₄H₈O₂ and is an ester. Its ¹H NMR spectrum has three peaks: δ 3.7 (singlet, relative peak area 3), δ 2.3 (quartet, relative peak area 2) and δ 1.1 (triplet, relative peak area 3). Its ¹³C NMR spectrum has four peaks.
Use the ¹H NMR data to deduce the structure of compound Z. Explain the singlet, the quartet and the triplet.3 marks

Written by the Exaim team, led by Shaun Daswani (Head of Upper Secondary, Improve ME Institute; MSc Financial Mathematics, Imperial College London; BSc, UCL) and Jason Daswani (operational lead, Improve ME Institute; LSE).