In which of the following organic conversions is the reaction initiated by the attack of an electrophile on the organic reactant?
CH3CH2CH2Br→CH3CH2CH2NH2\text{CH}_3\text{CH}_2\text{CH}_2\text{Br} \rightarrow \text{CH}_3\text{CH}_2\text{CH}_2\text{NH}_2CH3CH2CH2Br→CH3CH2CH2NH2
C6H10→C6H11Cl\text{C}_6\text{H}_{10} \rightarrow \text{C}_6\text{H}_{11}\text{Cl}C6H10→C6H11Cl
CH3COCH3→CH3C(OH)(CN)CH3\text{CH}_3\text{COCH}_3 \rightarrow \text{CH}_3\text{C(OH)(CN)CH}_3CH3COCH3→CH3C(OH)(CN)CH3
CH3CH2CH3→CH3CH(Cl)CH3\text{CH}_3\text{CH}_2\text{CH}_3 \rightarrow \text{CH}_3\text{CH(Cl)CH}_3CH3CH2CH3→CH3CH(Cl)CH3