UPSC Combined Geo-Scientist, Mains · 2016 · Mains Paper III
Q7(f). Frontier orbital nodes
Question
Sketch the HOMO of 1,3-butadiene and the LUMO of the allyl cation, showing nodes.
Answer in brief
Butadiene HOMO is ψ₂ with one intercarbon node; allyl-cation LUMO is nonbonding ψ₂ with zero amplitude on the central carbon.
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CoversFrontier orbital nodesMolecular orbitals
All parts of Question 7
- 7(a) Acidity and hybridisation4 marks
- 7(b) Dichlorocarbene addition4 marks
- 7(c) Grignard addition to a keto ester4 marks
- 7(d) Dipole moment of cyclopropenone4 marks
- 7(e) Cannizzaro reaction4 marks
- 7(f) Frontier orbital nodes4 marks
- 7(g) Keto–enol claim: correction4 marks
- 7(h) Hofmann rearrangement and oxidation4 marks
- 7(i) Carbonyl stretching order4 marks
- 7(j) Carbon count from isotope peaks4 marks