Q6(j). NMR assignment of 4-methylpent-1-yne
Compound A exhibits the following spectral data: ¹H NMR (400 MHz, CDCl₃): δ 2.5 (s, 1H); 2.0 (d, 2H); 1.7 (m, 1H); 1.0 (d, 6H). ¹³C NMR (CDCl₃): δ 80, 70, 40, 30, 20. Assign the peaks of protons and carbon in compound A and justify your answer. [structure of A given in the paper]
Answer in brief
¹H: 2.5 ≡C–H; 2.0 CH₂; 1.7 CH; 1.0 two CH₃. ¹³C: 80 C-2; 70 C-1; 40 CH₂; 30 CH; 20 two CH₃.
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Covers1H NMR13C NMRterminal alkynediamagnetic anisotropy4-methylpent-1-yne
All parts of Question 6
- 6(a) Singlet and triplet carbenes; fluorenylidene with cis-but-2-ene4 marks
- 6(b) Bromine addition: styrene reacts faster than propene4 marks
- 6(c) Addition of HCl to an α,β-unsaturated acid4 marks
- 6(d) Michael addition of a cyclic 1,3-dione to cyclohex-2-enone4 marks
- 6(e) Hydroboration–oxidation of 1-methylcyclohexene4 marks
- 6(f) Cope rearrangement of a 1,5-diene4 marks
- 6(g) Diels–Alder reaction: product and reactants4 marks
- 6(h) IR distinction: hydrogen bonding and ring strain4 marks
- 6(i) McLafferty rearrangement: 2-pentanone and 3-pentanone4 marks
- 6(j) NMR assignment of 4-methylpent-1-yne4 marks