Preparation of aldoxime through direct ammoximation using titanium silicalite-1 catalyst

Abstract The liquid phase direct ammoximation of 5-isooctyl salicylaldehyde with ammonia and hydrogen peroxide was studied using titanium silicalite-1 (TS-1) catalyst. The effect of reaction parameters on the yield of the product was studied, which include reaction temperature, reaction time, molar ratio of ammonia to aldehyde as well as hydrogen peroxide to aldehyde. The influence of the amount of catalyst on the reaction results was also investigated. The maximum 5-isooctyl salicylaldoxime yield of 98.76% was achieved under the following optimal reaction conditions: the molar ratio of 5-isooctylaldehyde to hydrogen peroxide and ammonia was 1:1.4:1.6, the reaction temperature of 70 °C, the amount of TS-1 of 17.5 g·mol-1(5-isooctyl salicylaldehyde), and the feeding time of 2 h. This method has the mild reaction conditions and avoids the shortcomings of traditional methods. Moreover, useless inorganic salts by-products are avoided, and there is no environmental pollution.