One-step 2,6-lutidine synthesis from acetone, ammonia and methanol. Temperature-programmed desorption–reaction (TPDR)–mass spectrometry (MS) study

Abstract

The temperature-programmed desorption–reaction (TPDR)–mass spectrometry (MS) technique has been employed to study the behaviour and the reactivity of the title reactant mixture over a catalyst of amorphous silica–alumina impregnated with Sb₂O₃ and CuO. This catalyst exhibited acidic and redox properties, leading to oxidation, dehydration and alkylation reactions.

The formation of 2,6-lutidine takes place only at high temperature, requiring a high activation energy. The reaction mechanism involves alkylation of acetone by methanol to form methyl ethyl ketone, followed by reaction of the latter with ammonia to form an imine, then reaction of the imine with a second molecule of acetone, and finally, cyclisation to 2,6-lutidine.