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Two compounds A and B with same molecular formula (C3H6O) undergo Grignard's reaction with methylmagnesium bromide to give products C and D. products C and D show following chemical tests. Test | C | D Ceric ammonium nitrate Test | Positive | Positive Lucas Test | Turbidity obtained after five minutes | Turbidity obtained immediately Iodoform Test | Positive | Negative C and D respectively are:

1. C = H3C–C(CH3)2–OH; D = H3C–CH2–CH(OH)–CH3
2. C = H3C–CH2–CH2–CH2–OH; D = H3C–C(OH)(CH3)2
3. C = H3C–CH2–CH(OH)–CH3; D = H3C–C(CH3)2–OH
4. C = H3C–CH2–CH2–CH2–OH; D = H3C–CH2–CH(OH)–CH3

Correct answer: C = H3C–CH2–CH(OH)–CH3; D = H3C–C(CH3)2–OH

Solution

Propanal + CH3MgBr -> 2-butanol (CH3CH2CH(OH)CH3): secondary, Lucas in ~5 min, positive iodoform = C. Acetone + CH3MgBr -> tert-butanol (CH3C(CH3)2OH): tertiary, immediate Lucas, negative iodoform = D.

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