My chemistry teacher told me that Bromine radical is a weak electrophile, and that it is more likely to join the more electron rich part of a molecule.

However I could not verify his statement from any book or Google.

Hence I am asking this question on this website: Is bromine radical electrophilic in nature or is there some other reason as to why bromine radical joins the more electron rich part of the molecule?

  • 1
    $\begingroup$ yes, Br• can be considered 'electrophilic', see e.g. Carey/Sundberg 5th ed, Part A, pg 1004, or also this Q&A on radical chlorination. Similar arguments apply to bromination. chemistry.stackexchange.com/q/49850/16683 Note, however, that because Br• is more stable than Cl•, typically the energy of the next radical that is formed plays a greater role in determining selectivity, rather than the energy of the transition state leading to that radical $\endgroup$ – orthocresol Jul 23 '18 at 11:20
  • $\begingroup$ The statement "Because Br radical is more stable than Cl radical, energy of next radical that is formed plays greater role in determining selectivity" brings up another question. If 1-(1-Bromoethyl)-4-methylbenzene reacts with 1 equivalent of NBS, on which carbon will the bromination occur? The benzylic carbon with three hydrogen or the benzylic carbon that has a bromine as well as a CH3 group attached to it (the CH3 group can stabilise the radical formed by hyperconjugation)? $\endgroup$ – Aumkaar Pranav Jul 23 '18 at 11:53
  • $\begingroup$ @orthocresol can you please answer the question I asked in my comment? :) $\endgroup$ – Aumkaar Pranav Jul 25 '18 at 3:43
  • $\begingroup$ It's not clear cut (to me, at least). Please don't ask full questions in comments - either add it into your existing question by editing the post (since it provides context for the original question), or ask a new one. $\endgroup$ – orthocresol Jul 25 '18 at 6:03

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