Abstract: Oxidation catalysts of the general formulaMo.sub.12 P.sub.a W.sub.b Sb.sub.c As.sub.d Cu.sub.e X.sub.f O.sub.xwhereX is Nb, Fe, Mn, Sn and/or Cr,a is 0.1-3,b is 0.1-4,c is <0-2,d is 0-1,e is 0-1,d+e is <0-2,f is 0-1.5,e+f is 0-2 andx is the number of oxygen atoms formally required to saturate the valencies of the other catalyst components,may be used particularly advantageously for the preparation of methacrylic acid by gas phase oxidation of methacrolein.

Abstract: Aromatic mono or polycarboxylic acid glycidyl esters are obtained in good yields and high purity by transesterification of the corresponding aromatic carboxylic acid alkyl esters with glycidol in the presence of weakly toxic catalysts, namely the alkali, ammonium, and alkaline earth metal salts of pseudohalogen hydride acids with readily polarizable anions.

Abstract: A catalyst which is free from alkali metal compounds and alkaline earth metal compounds, contains palladium and lead as active constituents and is supported on a carrier which contains two or more of the oxides ZnO, Al.sub.2 O.sub.3, La.sub.2 O.sub.3 and TiO.sub.2, and the use of this catalyst for the preparation of methyl methacrylate from methacrolein, methanol and oxygen.

Abstract: Oxidation catalysts of the general formulaW.sub.6 Mo.sub.a V.sub.b P.sub.c Cu.sub.d As.sub.e Sb.sub.f X.sub.g Y.sub.h O.sub.xwhere X is K, Rb and/or Cs, Y is Nb, Fe, Mn, Sn, Li, Na, Sr, Rh, Ce, Ti and/or Cr, a is from 2.0 to 6, b is from 0 to 3, c is from 0.1 to 3, d is from 0.01 to 1, e is from 0 to 1, f is from 0 to 2, g is from 0.01 to 3, h is from 0 to 1 and x is the number of oxygen atoms formally required to saturate the valencies of the catalyst components, give high conversions and particularly high selectivity in the oxidation of methacrolein in the gas phase to methacrylic acid.

Abstract: Catalysts for the preparation of carboxylates from an aldehyde and an alkanol in the presence of oxygen, which contain palladium and lead as active components, these being present on a carrier containing zinc oxide, and the palladium being applied as a palladium salt in a solution containing hydrochloric acid and then being liberated by reduction, and whose carrier consists solely of zinc oxide, are particularly active and selective.

Abstract: .alpha.-Alkylacroleins are prepared by a process wherein an alkanal is reacted with formaldehyde in the presence of a secondary amine and in the presence or absence, of an acid, in the liquid phase, under superatmospheric pressure and at above 150.degree. C., for not more than 25 minutes.The .alpha.-alkylacroleins obtainable by the process are useful starting materials for dyes, drugs and pesticides.