The total number of possible isomers (both structural as well as stereoisomers)
of cyclic ethers of molecular formula $C_4H_8O$ is :
Explanation:
Hint: Calculate the degree of unsaturation to draw the structures.
(1) Five-membered ring
1. Tetrahydrofuran (THF)
- Type: Structural
- Achiral
Count = 1
(2) Four-membered ring (Oxetanes)
2–3. 2-Methyloxetane
- Type: Optical isomers
- (R) and (S) forms
Count = 2
4–5. 3-Methyloxetane
- Type: Optical isomers
- (R) and (S) forms
Count = 2
(3) Three-membered ring (Epoxides / Oxiranes)
6–7. 1,2-Epoxybutane (Butylene oxide)
- Type: Optical isomers
- (R) and (S) forms
Count = 2
8. 2,2-Dimethyloxirane
- Type: Structural
- Achiral
Count = 1
9–10. 2,3-Dimethyloxirane
- Type: Geometrical + optical
- cis (meso) = 1
- trans (enantiomeric pair) = 2
Count = 3
Final total:
Total = 10
#535175
Exam: NEET – 2025
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