NMR spectroscopyEdexcel International A Level Chemistry: Mind map

Exam questions on NMR spectroscopy

1. 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
2. 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
3. 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