Studies on the liquid-phase ammoximation of cyclohexanone over a titanium silicate sieve using on-line ATR–FTIR spectroscopy

The liquid-phase ammoximation of cyclohexanone over a titanium silicate sieve is followed in real time using on-line ATR–FTIR spectroscopy. We have discovered the formation and the vanishment of an intermediate during the reaction with the aid of on-line ATR–FTIR spectroscopy. A new possible reaction mechanism is proposed according to the experimental results. Hydrogen peroxide is firstly adsorbed on titanium silicate sieves, forming a complex peroxidic species of titanium, which can react with cyclohexanone to form an intermediate. Then the intermediate reacts with ammonia to give cyclohexanone oxime. The infrared spectra indicate that the intermediate has strong absorption of C–O bond.