IIT JEE , AIEEE Forum - Chemistry , Organic Chemistry - Why only HBr shows peroxide effect and why not other halogen acids?

ashishchawla90

Why only HBr shows peroxide effect and why not other halogen acids?

paddy.dude

i think the answer lies in the mechanism involved ie peroxide addition is a free radical mechanism.........

sriram.a

HF,HCl,HI cannot be used in the peroxide effect.Since HF&HCl have high bond dissociation when compared to ROOR.The free radical cannot break HF,HCl bonds.In case of HI it is a powerfull reducing agent it destroys the oxidising power of ROOR.
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5timelucky

Coz HBr due its lesser difference in electronegativity, breaks homolytically and gives radicals which others dont and is imp feature of Kharash effect!!

shashankparewar

it is a very detailed topic but i am discussig in brief hf has a strong bond energy so it doesnt break homolytcaly whereas in case of HI the I free radical formedinstead of attacking the substrate combines in itself to form I2.

ashish040191

this reaction proceeds as a free radical mechanism. HBr breaks as H & Br radical. peroxide molecule split into 2 molecule (radical). and peroxide get attached to Hradical.change in G during this combined process is -ve.

in other haloacids one of the process is highly endothermic and hence kharash effect is seen only in HBr

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