An efficient and practical synthesis of methylene dioximes by combination of ultrasound and phase transfer catalyst.

The reaction of oximes with dichloromethane was carried out in 71-98% yields at 20-30 degrees C for 2-3.5h in the presence of sodium hydroxide by combination of benzyldimethyltetradecylammonium chloride and ultrasonication. The main advantage of the present procedure is that the reaction time is much shorter than classical methods.