1,4-DIDEHYDRONAPHTHALIN

The energy profile of the Bergman equilibrium o-diethinyl-benzene (1) reversible arrow 1,4-didehydronaphthalene (2) has been established fro m the temperature and NO dependence of the trapping rate of the diradi cals 2 which leads to a heat of formation for 2 of Delta H-f degrees = 152.9 +/- 1.4 kcal . mol(-1). Activation parameters for the hydrogen abstraction of 2 and 1,4-didehydrobenzene (5) have been derived from t he rate of the naphthalene and benzene formation, when 1 and cis-3-hex ene-1,5-diyne (4) are heated in the presence of methanol, toluene, and 1,4-cyclohexadiene.