About the Routes of Oxidative Conversion of 2-methyl-5-ethylpyridine on Vanadium Oxide Modified Catalyst

<p>The vapor phase oxidation of 2-methyl-5-ethylpyridine (MEP) on modified vanadium oxide catalyst has been investigated. Di(5-ethyl)-2-pyridil, 2-methyl-5-acethylpyridine and 3-acethylpyridine have been identified as intermediates of MEP oxidation by NMR ¹³C spectroscopic and gas chromatography mass spectrometry methods. It has been shown that the interaction between the pyridine base and acidic proton donating sites on the catalyst surface causes an increase of substituents reactivity in 2-position in all stages of 2-methyl-5-ethylpyridine transformation inducing their oxidative elimination. A distinction in composition of the oxidation products is an outcome of a change of the dialkylpyridine substituents in 2- and 5-position contribution. Using literature and experimental data the basic routes of the 2-methyl-5-ethylpyridine oxidative conversion have been determined. The ammoxidation is a process based on the joint oxidation of the initial organic substance and ammonia by air oxygen in the presence of a catalyst [1]. The basic step of ammoxidation is a vapor phase catalytic oxidation, which determines the main routes of the former. Therefore, the obtained results give a possibility for the first time to explain the reason for the change of selectivities during MEP ammoxidation in the present of water.</p>

Optimization of vanadium oxide catalyst for the oxidation of 3-methylpyridine into nicotinic acid

Upon modification of V2O5 with SnO2 or ZrO2, increase in the activity and selectivity of the vanadium-oxide catalyst in the vapor-phase oxidation of 3-methylpyridine into nicotinic acid were observed. It was shown that the promoting effects of SnO2 and ZrO2 were the result of increases under their influence of the proton affinity of the vanadyl oxygen and decreases in the enthalpy of deprotonation of the methyl group of the substrate, connected by a nitrogen atom with the Lewis acidic center (vanadium ion). The given characteristics were calculated by the density functional theory quantum-chemical method. Modification of binary V2O5?SnO2 and V2O5?ZrO2?catalysts by TiO2 addition resulted in a further increase in the nucleophility of the vanadyl oxygen and, as a consequence, an increase in the catalytic activity and selectivity for nicotinic acid formation.