Q8(a). Assignment of four C=O stretching bands
An ethanolic solution of compound I on irradiation gives compounds II, III and IV. The resulting reaction mixture exhibits bands at 1787, 1740, 1715 and 1685 cm⁻¹ for νC=O. Assign these C=O stretching frequencies to the corresponding compounds, giving reasons. [structures of I to IV given in the paper]
Answer in brief
1787 cm⁻¹: II; 1740 cm⁻¹: IV; 1715 cm⁻¹: III; 1685 cm⁻¹: I (unchanged starting ketone).
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CoversIR carbonyl stretchingring strainconjugationcyclobutanoneverbenone photochemistryNorrish type I
All parts of Question 8
- 8(a) Assignment of four C=O stretching bands15 marks
- 8(b)(i) Ring opening of 2,2-dimethylcyclopropanone by methoxide10 marks
- 8(b)(ii) Order of J(Ha–Hb)5 marks
- 8(c)(i) Two alkenes from 2-chloro-2,3-dimethylbutane10 marks
- 8(c)(ii) Fragmentation of diethyl ether5 marks
- 8(c)(iii) Bond length of HCl from its moment of inertia5 marks