Protonation of Diarylcarbenes by Alcohols: The Importance of Ion Pair Dynamics

Article abstract of DOI:10.1021/j100099a025

Picosecond laser excitation of either di(p-chlorophenyl)- or di(p-methoxyphenyl)diazomethane generates a transient which we ascribe to the singlet states of di(p-chlorophenyl)- and di(p-methoxyphenyl)carbenes, 1a and 1b, respectively.Picosecond absorption spectroscopy is used to determine their kinetic behavior in various solvents.In the presence of alcohols, these carbenes are protonated, forming contact-ion pairs.These ion pairs partition between collapse to ether products and separation to free carbenium ions, 2a and 2b, which are readily observed.The dynamics of these ion pairs is discussed.Protonation of carbenes can provide an alternative method for the preparation of ion pairs and the investigation of their dynamics.