Abstract: There is provided a process for preparing a heteroaromatic aldehyde by catalytic reaction of alkyl-substituted heteroaromatic compound with molecular oxygen in a gaseous phase in the presence of a catalyst, which comprises employing an oxide containing vanadium, phosphorus, aluminium and silicon as a catalyst, and diluting a part or all of the oxide present as a catalyst layer in a reactor with a solid inert to the reaction.

Abstract: A process for producing a pyrazine compound of the general formula (3): ##STR1## wherein R.sup.1, R.sup.2, R.sup.3 and R.sup.4 represent a hydrogen atom or a lower alkyl group, which comprises catalytically reacting in a gaseous phase a diamine compound of the general formula: ##STR2## with a diol compound of the general formula: ##STR3## in the presence of a catalyst containing hydrogen-treated silver or a catalyst containing silver and at least one element selected from the group consisting of alkali metals, alkaline earth metals, zinc and lanthanoid elements.

Abstract: A heteroaromatic nitrile is prepared in high conversion and yield by catalytically reacting an alkyl-substituted heteroaromatic compound with molecular oxygen and ammonia in the presence of a catalyst having the following composition:Mo(P).sub.x (A).sub.y (B).sub.z (O).sub.w (I)wherein x, y, z and w represent atomic ratios of phosphorus, an element A defined below, an element B defined below and oxygen to molybdenum, respectively and(i) x and z are both 0 (zero), y is from 0.1 to 5, and A is at least one element selected from the group consisting of cerium and tungsten, or(ii) x is from 0.1 to 7, y is from 0 to 5, z is from 0 to 5, A is at least one element selected from the group consisting of cerium, manganese and tungsten, and B is at least one element selected from the group consisting of thallium, titanium, niobium and aluminum, or(iii) x is from 0.5 to 7, y is from 0 to 5, z is from 0.01 to 2.

Abstract: A heteroaromatic nitrile is prepared in a high selectivity and yield by catalytically reacting an alkyl-substituted heteroaromatic compound with molecular oxygen and ammonia in a molar ratio of oxygen to ammonia of not larger than 1.6:1 in a gaseous phase in the presence of a catalyst comprising a vanadium-phosphorus oxide of the formula:VP.sub.x Sb.sub.y O.sub.z (I)wherein x, y and z represent atomic ratios of phosphorus, antimony and oxygen to vanadium, respectively, and x is from 0.1 to 5, y is 0 to 8 and z is defined from the valencies of other elements.