An Addition-Metalation Reaction of Benzene with Phenylpotassium¹

Dual Roles for Potassium Hydride in Haloarene Reduction: CSNAr and Single Electron Transfer Reduction via Organic Electron Donors Formed in Benzene

“…In a manner reminiscent of other BHAS reactions, a strong organic electron donor could be formed if KH deprotonates benzene to form PhK 47 (Scheme ). Here, PhK would attack benzene to form phenylcyclohexadienyl potassium 35 . Whereas this anion might function as a mild electron donor, more likely it could be deprotonated again to form the disalt 48 , a biphenyl dianion and a known class of strong electron donors This could initiate electron transfer to haloarenes to trigger radical chemistry.…”

“…Alternatively, biphenyl could also be formed by expelling KH from anion 35 . Indeed, it is known that phenylpotassium attacks benzene to form biphenyl and an insoluble polybenzene . From our previous work on initiation of BHAS reactions, we know that the amount of initiator that needs to be present is vanishingly small, and that evidence of the electron donating initiator is generally not found in the products of these reactions.…”

“…Here, PhK would attack benzene to form phenylcyclohexadienyl potassium 35. 37 Whereas this anion might function as a mild electron donor, more likely it could be deprotonated again to form the disalt 48, a biphenyl dianion and a known class of strong electron donors 38 This could initiate electron transfer to haloarenes to trigger radical chemistry. Indeed, sequential transfer of two electrons would form biphenyl 12.…”

Alkyl and Aryl Derivatives of the Alkali Metals: Useful Synthetic Reagents as Strong Bases and Potent Nucleophiles. 1. Conversion of Organic Halides to Organoalkali-Metal Compounds

“…This procedure was reported to work well in the preparation of amylpotassium by reaction of amyl chloride with potassium sand, but the yield, as indicated by the yield of caproic acid after reaction with dry ice, was considerably lower . Others have reported the utility of this alkylpotassium synthesis claimed that the preparation of alkylpotassium compounds ( n -C 3 H 7 K, n -C 4 H 9 K, n -C 5 H 11 K) by the standard n -C 5 H 11 Na procedure was much more complex.…”

“…These RCl/Na reactions were sluggish, and the butyric and valeric acid yields obtained on carbonation were not high . Higher alkylsodium compounds also were prepared: n -C 8 H 17 Na and n -C 10 H 21 Na and n -C 12 H 25 Na and n -C 16 H 33 Na 76e. Also prepared was n -C 12 H 25 K 76e…”