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7946737 
Journal Article 
Characterization of 2-naphthylcarbene reactivity 
Chateauneuf, JE; Horn, KA 
1999 
1 
Research on Chemical Intermediates
ISSN: 0922-6168
EISSN: 1568-5675 
25 
9 
925-949 
English 
WOS:000083743400007 
Laser flash photolysis (LFP) and product analysis have been used to characterize 2-naphthylcarbene (2-NC) reactivity in solution. Absolute kinetics of 2-NC have been obtained by monitoring the electronic absorption of 2-NC at 362 nm following LFP of 2-naphthyldiazomethane. In both cyclohexane and toluene 2-NC reacts via hydrogen atom abstraction to give the 2-naphthylmethyl radical (λmax = 378 nm). The Arrhenius activation parameters (Ea = 5.0 ± 0.6 kcal/mol, log (A) = 9.9 ± 0.5) and large primary kinetic isotope effect (kH/kD = 2.65 ± 0.36) observed in cyclohexane indicate predominantly triplet carbene reactivity. In toluene, addition to the aromatic π system predominates and hydrogen atom abstraction is a minor pathway. The measured Arrhenius activation parameters (Ea =4.1 ± 0.1 kcal/mol, log (A) = 9.1 ± 0.1) and small kinetic isotope effect (kH/kD = 1.24 ± 0.09) reflect the minor contribution of triplet hydrogen atom abstraction to the composite rate constant for this reaction. Reactivity of 2-NC with carbon tetrachloride (CCl4) was also investigated. 2-NC reacts with CCl4 to produce 2-naphthylchloromethyl radical (λmax = 390 nm). Direct kinetic measurements indicated two pathways for radical production, rapid formation of radical through a proposed chloronium ylide and slow formation through chlorine atom abstraction by triplet carbene. Additionally, ylide and ylide like intermediates have been observed from the reactions of 2-NC with acetonitrile, acetone and molecular oxygen.