Hydrocarbons

Which alkene on ozonolysis gives CH3CH2CHO and CH3COCH3?

1. [figure]
2. CH3CH2CH=CHCH2CH3
3. CH3CH2CH=CHCH3
4. [figure]

Answer

(1) [figure]

Solution

On ozonolysis the C=C bond breaks and each carbon of the double bond becomes a C=O carbon.

To find the alkene, join the two carbonyl carbons by a double bond (removing both O atoms):

CH3CH2CH=O + O=C(CH3)2 CH3CH2CH=C(CH3)2

The alkene is 2-methylpent-2-ene, CH3CH2CH=C(CH3)2.

(2) gives only CH3CH2CHO; (3) gives CH3CH2CHO and CH3CHO; (4) gives CH3COCH3 and CH3CHO.

Answer: (1)