Process for effecting oxidative dehydrodimerization

A process for the catalytic oxidative dehydrodimerization of a substrate compound, ##STR5## to yield a product, ##STR6## wherein R.sup.2 is H, alkyl, phenyl, heteroaromatic containing a single N atom as the sole heteroatom, or cyano, and wherein R.sup.1 and R.sup.3 either (1) together complete a single ring aromatic group, (2) together with a single N atom complete a single ring heteroaromatic group containing only one heteroatom, or (3) are each independently selected from H, alkyl, phenyl, cyano or a single ring heteroaromatic group having one N atom as the sole heteroatom, with the proviso that when (3) is selected neither R.sup.1 nor R.sup.2 is bonded to the carbon containing the double bond by a carbon that is bonded to H, and

• wherein said substrate has 3-12 C atoms, said process comprising:
• (A) providing a crystalline, oxide ion conductive, catalyst in the form of a fluid-impervious membrane forming a wall separating a reaction zone and an oxidant supply zone so that fluid cannot flow from either zone to the other,
• (B) introducing said substrate into said reaction zone in the vapor or gaseous phase in contact with said catalyst, and
• (C) introducing a gas containing molecular oxygen into said supply zone in contact with said catalyst,
• the reaction zone and said catalyst being maintained at a temperature above 500.degree. C. at which the catalyst membrane conducts oxide ions across said membrane from the supply zone to the surface of the catalyst membrane forming a wall of the reaction zone, said crystalline, oxide ion conductive, catalyst having the atoms and atomic proportions indicated by the following empirical formula:
• BiL.sub.a M.sub.b O.sub.x
• wherein
• L is at least one of Y, V, Nb, Ta, W, Mo, Pb, La, Nd, Sm, Er, Yb, Dy and Gd;
• M is at least one of Ca, Ba, and Sr;
• a=0-1, and
• b=0-0.1.