text: Electrical conductivity Pure crystalline naphthalene is a moderate insulator at room temperature, with resistivity of about 1012 Ω m. The resistivity drops more than a thousandfold on melting, to about 4 × 108 Ω m. Both in the liquid and in the solid, the resistivity depends on temperature as ρ = ρ0 exp(E/(k T)), where ρ0 (Ω m) and E (eV) are constant parameters, k is Boltzmann's constant (8.617×10−5 eV/K), and T is absolute temperature (K). The parameter E is 0.73 in the solid. However, the solid shows semiconducting character below 100 K.
  Chemical properties
  Reactions with electrophiles
  In electrophilic aromatic substitution reactions, naphthalene reacts more readily than benzene. For example, chlorination and bromination of naphthalene proceeds without a catalyst to give 1-chloronaphthalene and 1-bromonaphthalene, respectively. Likewise, whereas both benzene and naphthalene can be alkylated using Friedel–Crafts reaction conditions, naphthalene can also be easily alkylated by reaction with alkenes or alcohols, using sulfuric or phosphoric acid catalysts.
  In terms of regiochemistry, electrophiles attack at the alpha position. The selectivity for alpha over beta substitution can be rationalized in terms of the resonance structures of the intermediate: for the alpha substitution intermediate, seven resonance structures can be drawn, of which four preserve an aromatic ring. For beta substitution, the intermediate has only six resonance structures, and only two of these are aromatic. Sulfonation gives the "alpha" product naphthalene-1-sulfonic acid as the kinetic product but naphthalene-2-sulfonic acid as the thermodynamic product. The 1-isomer forms predominantly at 25 °C, and the 2-isomer at 160 °C.