In the presence of peroxide addition of ...

In the presence of peroxide addition of HBr to propene takes place according to anti Markownikoff's rule but peroxide effect is not seen in the case of HCl and HI. Explain.

Text Solution

Verified by Experts

In presence of peroxides, addition of HBr to propene takes place according to anti-markovnikov's rule. The reaction occurs by a free radical mechanism as shown below :

In case of HBr both these steps are exothermic and hence peroxide effect is observed. However, in case of HCl or HI, either first on the second step is endothermic and hence peroxide effect is not observed.

Topper's Solved these Questions

HYDROCARBONS
PRADEEP|Exercise ADDITIONAL QUESTIONS (VERY SHORT ANSWER TYPE QUESTIONS )|30 Videos
HYDROCARBONS
PRADEEP|Exercise ADDITIONAL QUESTIONS (SHORT ANSWER QUESTIONS)|62 Videos
HYDROCARBONS
PRADEEP|Exercise NCERT EXEMPLAR PROBLEMS WITH ANSWERS, HINTS AND SOLUTIONS (ASSERTION AND REASON TYPE QUESTIONS)|4 Videos
EQUILIBRIUM IN PHYSICAL AND CHEMICAL PROCESSES
PRADEEP|Exercise Competition Focus (Jee(Main and advanced)/Medical Entrance) VIII. ASSERTION - REASON TYPE QUESTIONS (TYPE - II)|10 Videos
HYDROGEN
PRADEEP|Exercise COMPETITION FOCUS (Assertion-Reason Type Questions) Type 2|15 Videos

The addition of HBr to propylene takes place opposite to Markownikoff's rule in presence of:

sunlight

hydrogen peroxide

platinum catalyst

none of these

Addition of HBr to propene in presence of peroxide (antiMarkownikoff's additon) occurs when:

`Br^(+)` first adds to propene

`Br^(-)` first adds to propene

`H^(+)` first adds to propene

`Br^.` first adds to propene

The addition of HCl in the presence of peroxide does not follow anti-Markownikoff's rule because

HCl bond is too strong to be broken homolytically

Cl atom is not reactive enough to add on the a double bond

Cl combines with H to give back HCl

HCl is reducing agent