SPECTROSCOPIC CHARACTERIZATION OF 2-NAPHTHYLCARBENE

Article abstract of DOI:10.1016/S0040-4020(01)96387-2

The 308 nm excimer laser flash photolysis of 2-naphthyldiazomethane produces triplet 2-naphthylcarbene (λ_max=362 nm) which decays with the observed pseudo-first-order rate constants (k_exptl) of 5.54+/-0.03E6; 3.33+/-0.4E6; 1.64+/-0.02E7; and 3.05+/-0.4E6 s^-1 in n-pentane, 2,2,4-trimethylpentane (2,2,4-TMP), benzene and Freon 113 respectively.In hydrocarbon solvents the observed decay of triplet 2-naphthylcarbene is correlated with the pseudo-first-order growth of the 2-naphthylmethyl radical (λ_max=378 nm).Direct kinetic measurements of the reaction of triplet 2-naphthylcarbene in 2,2,4-TMP with cyclohexane, styrene, meth anol and carbon tetrachloride yielded bimolecular quenching rate constants of 1.48+/-0.04E6; 4.33+/-0.1E7; 7.25+/-0.5E6; and 3.35+/-0.07E6 M^-1s^-1.It is also found that 2-naphthylcarbene reacts with acetonitrile (k_q=5.28+/-0.1E5 M^-1s^-1) to form a nitrile ylide intermediate with a λ_max=372 nm.These results are interpreted in terms of a rapid singlet-triplet-2-naphthylcarbene equilibrium.