Process for preparing alkenyl-substituted pyridine or pyrazine

Described are preferred processes for preparing alkenyl-substituted nitrogenous heterocycles such as vinylpyridines, which comprise reacting a corresponding methyl-substituted heterocycle with a C1 compound such as formaldehyde in the vapor phase over a zeolite catalyst having acidic and basic catalytic sites. The preferred zeolite is a medium-pore zeolite, for example having a constraint index of about 0.5 to about 12. Processes of the invention can be conducted as facile, one-step syntheses utilizing relatively low ratios of alkyl-substituted starting heterocycle (e.g. alpha-picoline or gamma-picoline) to formaldehyde while nonetheless achieving high selectivities and yields of the corresponding alkenyl compound.