In SituFT-IR Study on the Blocking Reaction of Isocyanate with Naphthol

The blocking reactions of phenyl isocyanate with 1-naphthol and 2-naphthol were investigated with in situ FT-IR. The reaction kinetics was studied and the reaction rates were described by a second-order equation. It was found that there was a remarkable induction period in the reaction. The induction period shortened with increase of temperature, and the induction period of 1-naphthol was obviously longer than that of 2-naphthol. Activation energies and Eyring parameters were also determined for the blocking reaction with 1-naphthol (E a  = 55.3 kJ · mol−1, ΔH = 56.9 kJ · mol−1, ΔS = −120.8 J · mol−1 · K−1) and 2-naphthol (E a  = 74.2 kJ · mol−1, ΔH = 69.8 kJ · mol−1, ΔS = −79.8 J · mol−1 · K−1), respectively.