free radical halogenation

Question

Major monochlorination product of propane under radical conditions (excess Cl2, light) is:

RankGuru · Accepted Answer

1. **Radical Formation**: Under light (photolysis), Chlorine molecule cleaves into two Chlorine radicals ($Cl\cdot$).
2. **Hydrogen Abstraction**: The radicals can abstract a hydrogen from either a primary carbon ($CH_3$) or a secondary carbon ($CH_2$) of propane.
3. **Radical Stability**: A secondary propyl radical ($CH_3-\dot{C}H-CH_3$) is more stable than a primary propyl radical ($CH_3-CH_2-\dot{C}H_2$) due to greater hyperconjugation ($6$ versus $2$ alpha $H$-atoms).
4. **Statics vs. Stability**: Although there are $6$ primary hydrogens and only $2$ secondary hydrogens, the stability advantage of the secondary radical makes it the faster route.
5. **Major Product**: The stable secondary radical then reacts with $Cl_2$ to form **2-Chloropropane (Isopropyl chloride)**.

Rank Guru

free radical halogenation

Select the correct option: