Alkylpotassium compounds

Alkylsodium and alkylpotassium compounds are highly reactive and are among the most powerful of bases => they react explosively with water and burst into flame when exposed to air. 

The alkylation of benzene by alkylpotassium compounds has been reported by Bryce-Smith (S9) and is probably due to the increased base strength of organopotassium compounds over organosodium compounds. The potassium hydride eliminated in the cyclization reaction may add to ethylene to form ethylpotassium, which then may react with the aromatic to yield ethane and a benzylic carbanion [Reactions (16) and (17)]. 

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