# Reaction rate of Mg with aryl halides

I have been thinking of the rate of reaction of aryl bromide and aryl chloride with $$\ce{Mg}$$ to form Grignard.

When considering the electronegativities the carbon in aryl chloride is more positively polarized. But when considering the bond energies carbon chlorine bond is stronger.

I want to know which factor is more significant when we consider the reaction rates of aryl chloride and aryl bromide with $$\ce{Mg}$$ to form Grignard.

• Bond energy is key. Magnesium is easily electropositive enough to barrel its way in unless facing a high activatiin energy. – Oscar Lanzi Jun 25 at 15:57
• So that means aryl bromide forms grignard faster than aryl chloride right? – AfiJaabb Jun 26 at 7:46
• On target. In fact bromides generally react faster than chlorides. – Oscar Lanzi Jun 26 at 9:30