Abstract: Substituted pyridines of the formula ##STR1## where R.sup.1 is alkyl of 1 to 20 carbon atoms, cycloalkyl, aryl or aralkyl, are prepared by reacting a mixture of acrolein and alkanals of the formula ##STR2## with ammonia in the presence of zeolites as catalysts.

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: 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: Dienes are prepared by dehydration of aldehydes at elevated temperatures by a method in which the dehydration is carried out using a zeolite as a catalyst.

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.

Abstract: Pyridines are prepared by reacting a 2-alkoxy-2,3-dihydro-4H-pyran or a glutaraldehyde with ammonium nitrate in the presence of an aliphatic carboxylic acid and a catalytic amount of nitric acid.The pyridines which can be prepared by the process according to the invention are useful starting materials for the preparation of dyes, drugs and pest control agents and are useful solvents.

Abstract: Formaldehyde is prepared by dehydrogenation of methanol in the presence of a catalyst containing copper, zinc and tellurium, at from 300.degree. to 750.degree. C.The formaldehyde obtainable by the process of the invention is a disinfectant, tanning agent, reducing agent and valuable starting material for the preparation of synthetic resins, adhesives, plastics and auxiliaries in numerous sectors of industry.

Abstract: Methyl methacrylate is prepared by reacting methyl propionate and methanol at 200.degree.-550.degree. C. over a catalyst mixture which has a condensing action and is capable of dehydrogenating methanol to formaldehyde.

Abstract: Propylene oxide is prepared by elimination of water from propylene glycol which in turn is obtainable from propylene glycol acetate. The water is eliminated in the gas phase over a solid catalyst which consists of a weakly acidic carrier and an alkaline additive. The process offers a new method of manufacturing propylene oxide.

Abstract: Methacrylic acid and methyl methacrylate are manufactured by reacting, respectively, propionic acid and methyl propionate with dimethoxymethane in the presence of catalysts based on phosphates and/or silicates of magnesium, calcium, aluminum, zirconium, thorium and/or titanium, and in the presence of from 0 to 0.5 mole of water per mole of the acetal.