Q7(c). Ring opening of 2,2-dimethylcyclopropanone: structure from spectra
2,2-Dimethylcyclopropanone undergoes ring opening when attacked by methoxide ion; the product obtained possesses the following spectral properties: IR (ν cm⁻¹): 1740, 1160; ¹H NMR (δ): 3.6 (3H, s), 1.2 (9H, s); Mass (m/z): 116, 85, 59, 31. Deduce the structure of the product and explain its formation. Also write the structure of the other possible product.
Answer in brief
The product is methyl 2,2-dimethylpropanoate (methyl pivalate), (CH₃)₃C–COOCH₃; the other possible product is methyl 3-methylbutanoate, (CH₃)₂CH–CH₂–COOCH₃.
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Coverscyclopropanone ring openingFavorskii rearrangementmethyl pivalatestructure from spectra
All parts of Question 7
- 7(a) Phenol to salicylaldehyde to a coumarin ester10 marks
- 7(b) Maleic anhydride with anthracene, furan and pyrrole12 marks
- 7(c) Ring opening of 2,2-dimethylcyclopropanone: structure from spectra8 marks