Q2(d). Aromatic character of sydnones
Write a short note on aromatic character of sydnones.
Answer in brief
Sydnones are mesoionic aromatic compounds : a planar 6π ring carrying a delocalised positive charge, with the negative charge on the exocyclic oxygen. Stability, large dipole moment and electrophilic substitution at C-4 show aromatic character; 1,3-dipolar cycloaddition shows that it is only moderate.
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CoversmesoionicSix π electronsLarge dipole momentElectrophilic substitutionpyrazoles
All parts of Question 2
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- 2(c)(i) Bromolactonisation of endo-norbornene-carboxylic acid5 marks
- 2(c)(ii) Octalin to the tertiary and the secondary decalol5 marks
- 2(d) Aromatic character of sydnones10 marks