Abstract: Polymers having recurring succinyl units are obtained by an improved process by reaction of A, an unsaturated C.sub.4 -dicarboxylic acid or a derivative thereof, with B, a nitrogen-donating compound, in a first reaction step to give a reaction mixture comprising at least one low molecular weight reaction product, and subsequent continuous feeding of the reaction mixture into a continuously operated reactor to give the polymer in a second reaction step. In a further embodiment the invention refers to polymers having recurring succinyl units prepared by reaction of an unsaturated C.sub.4 -dicarboxylic acid or a derivative thereof with a nitrogen-donating compound in a first reaction step and subsequent feeding of the reaction mixture, without intermediate isolation, into an optionally continuously operated reactor, with removal of water, and treatment of the reaction mixture at a temperature of 140 to 350.degree. C.

Abstract: Aromatic amines are produced by catalytic hydrogenation of nitroaromatic compounds in the gas phase. The catalyst includes palladium and lead on graphite or on a graphite-containing coke support. From 30 to 6000 equivalents of hydrogen for each equivalent of nitro groups are contacted with the catalyst during this process.

Abstract: 4-aminodiphenylamines are produced by hydrogenating nitrobenzene with hydrogen in the presence of bases containing hydroxide and/or oxide groups and heterogeneous catalysts and in the presence of inert aprotic solvents at temperatures of 0 to 200.degree. C. and pressures of 0.1 to 150 bars.

Abstract: Aromatic amines are produced by hydrogenation of the appropriate aromatic nitro compounds in the vapour phase on fixed catalysts. The catalysts contain supported metals active in hydrogenation, the reaction is carried out under adiabatic conditions at a pressure of from 1 to 30 bar, an inlet temperature of from 200.degree. to 400.degree. C. and a maximum catalyst temperature of 500.degree. C.

Abstract: Aromatic amines are produced by hydrogenation of the associated aromatic nitro compounds in the gas phase over fixed catalysts. The catalysts contain active hydrogenation metals on supports. The reaction is conducted at a pressure of 2-50 bar and at a temperature in the range 250.degree.-500.degree. C. under adiabatic conditions. A circulating gas is passed over the catalyst, which circulating gas contains 3-150 moles of hydrogen, 2-100 moles of the amino groups to be formed per mole of nitro groups, and 2 to 6 moles of water per amino group equivalent. The amine and water formed, as well as a purification stream, are separated from the circulating gas. Thereafter the circulating gas is enriched with volatilised aromatic nitro compound and fresh hydrogen and recycled.

Abstract: Aromatic amines are produced by catalytic hydrogenation of nitroaromatic compounds in the gas phase. The catalyst includes palladium and lead on graphite or on a graphite-containing coke support. From 30 to 6000 equivalents of hydrogen for each equivalent of nitro groups are contacted with the catalyst during this process.

Abstract: New hydrated niobium oxide and hydrated tantalum oxide catalysts containing pores having diameters in the range from 0.4 to 10,000 nm are characterized in that the volume of the pores of the catalyst having a diameter of from 100 to 1000 nm is at least 30% of the total pore volume of the catalyst. The catalysts can be prepared by mixing hydrated niobium oxide or hydrated tantalum oxide with an inert solid and converting this mixture into a solid pellet form, with the pressure in the apparatus for preparing catalysts in pellet form being set in such a way that the volume of the pores of the catalyst having a diameter of from 100 to 1000 nm is at least 30% of the total pore volume of the catalyst. Such catalysts are particularly suitable for preparing N-alkylanilines from anilines and alkanols.

Abstract: Mixtures of m- and p-dichlorobenzene can be separated by treating such mixtures in the liquid phase with a pentasil zeolite at from 20.degree. to 250.degree. C., a filtrate enriched in m-dichlorobenzene being removed and the p-dichlorobenzene being obtained by desorption of the pentasil zeolite. The pentasil zeolites may contain, as exchangeable cations, protons, cations of the first or second main group of the Mendeleev Periodic System, cations of the rare earth metals or a mixture of a plurality thereof. In order to prepare the liquid phase a solvent is used that belongs to the group of cyclic saturated hydrocarbons having 5 to 15 carbon atoms, alkyl-substituted aromatic hydrocarbons having 8 to 12 carbon atoms, and halogen-substituted aromatic hydrocarbons having 6 to 10 carbon atoms and 1 to 3 halogen atoms. The solvents ethylbenzene, chlorobenzene, p-xylene, p-chlorotoluene and dichlorobenzene are excepted. A mixture of a plurality of these solvents may also be used.