Abstract: C.sub.1 -C.sub.4 -Alkyl nitrites can be prepared by reaction of C.sub.1 -C.sub.4 -alkanols with nitrogen oxides with the participation of oxygen in a reactor designed as a scrubber column, nitrogen oxides having a proportion of more than 50% of NO of the total amount of gram atoms of N of the nitrogen oxides, oxygen and optionally inert gas being fed into the lower part of the reactor. 5 to 60% of the total amount of C.sub.1 -C.sub.4 -alkanol used is likewise fed into the lower part of the reactor in vaporous or atomized form, while the remaining C.sub.1 -C.sub.4 -alkanol is delivered to the column head.

Abstract: In a process for the continuous preparation of polymers with repeating succinyl units, maleic anhydride or a derivative thereof as educt A is mixed with ammonia or an ammonia-producing compound or amides of carbonic acid as educt B and in a first reaction stage these are reacted to give an N-containing low molecular derivative of maleic acid. This derivative is then polymerized in a subsequent second reaction stage. Reaction of the educts (A,B) takes place largely adiabatically in the first reaction stage. The heat of reaction thereby released is used to take the reaction mixture to the polymerization temperature and in the second reaction stage at least partially to polymerize the N-containing low molecular derivative to obtain a polymer with repeating succinyl units.

Abstract: Alkyl nitrite-containing exhaust gases are purified in continuous form by treating them with equimolar to excess amidosulphuric acid in the form of an aqueous solution in the manner of a counter-current scrubbing at a temperature of 0.degree.-100.degree. C.

Abstract: A process is described for working up liquid reaction mixtures such as are formed during dimethyl carbonate preparation by oxidative carbonylation of methanol in the presence of a copper-containing catalyst, which process permits a simple separation of the water of reaction from the dimethyl carbonate. In this process, in a first distillation column, the water of reaction is taken from the bottom of the column; the top product from the first column is separated in a second column, under increased pressure, into dimethyl carbonate as bottom product and into a top product which is predominantly composed of methanol. The top product from the distillative working-up in the second column, which is predominantly composed of methanol, is recycled to the reaction process.

Abstract: Polyaspartic acid is prepared by reacting maleic anhydride and ammonia to give maleamic acid, polymerizing the maleamic acid and subsequently hydrolyzing the product to give polyaspartic acid or a salt thereof.

Abstract: Dimethyl carbonate (DMC) is prepared by continuous gas reaction of carbon monoxide and methyl nitrite a heterogeneous catalyst comprising a platinum at 50.degree. to 170.degree. C. under 1 to 5 bar.

Abstract: Molten maleic anhydride is introduced in the form of fine droplets at 53.degree. C. to 250.degree. C. and preferably at 60.degree. C. to 120.degree. C. into a gas atmosphere which consists either of pure gaseous ammonia or of a gas mixture of ammonia and at least one other gas and of which the temperature is between 20.degree. C. and 500.degree. C. The process is carried out at a temperature of 120.degree. C. to 180.degree. C. for the production of polysuccinimide and at a temperature of 10.degree. C. to 120.degree. C. for the production of maleic amide acid.

Abstract: Organic carbonates which contain at least one aromatic ester group can be obtained continuously from carbonates, which contain at least one aliphatic ester group, and a phenolic compound in the presence of a transesterification catalyst known per se in that the reaction is carried out in a bubble column reactor or in a cascade of at least two bubble column reactors in such a way that the phenolic compound is metered into the first bubble column and the carbonate containing at least one aliphatic ester group is metered into each individual bubble column, but preferably only into the last bubble column. The carbonate containing at least one aromatic ester group is taken off in the liquid state from the last bubble column. Volatile reaction products, for example eliminated alcohol or a dialkyl carbonate are taken off at the upper end of each individual bubble column, preferably at the upper end of the first bubble column.

Abstract: Ethylene glycol carbonate (EGC) can be isolated in purified form from contaminated material which contains impurities from the group comprising starting materials, by-products and/or catalysts of the preparation process in that the contaminated EGC is subjected to a fractional melt crystallization and the crystals of the purified EGC formed in this case are mechanically separated off from the remaining impurities dissolved in the residual melt.

Abstract: A bubble column reactor is described which is characterized by a slenderness ratio at a ratio of height to diameter of 2 to 50, a feed, at the bottom end of the bubble column, for the ethylene glycol carbonate (EGG) or propylene glycol carbonate (PGC) already present serving as reaction medium, one or more metering sites for the starting materials CO.sub.2 and ethylene oxide (EOX) or propylene oxide (POX) above the feed for the reaction medium, an outlet for the reaction mixture at the top end of the bubble column, a dividing apparatus connected thereto for the reaction mixture flowing off for dividing it into reaction mixture to be taken off and worked up on the one hand and reaction mixture to be recycled on the other hand and additionally a return line to the feed for the reaction mixture to be recycled. This bubble column reactor can be advantageously used in a process for the continuous preparation of EGG or PGC which is carried out in the temperature range from 100.degree. to 200.degree. C.

Abstract: The invention relates to a process for the continuous preparation of diaryl carbonates by reaction of an aromatic hydroxyl compound with carbon monoxide and oxygen in the presence of a catalyst containing a noble metal of group VIIIb of the Periodic Table of the Elements, a quaternary salt, a cocatalyst and a base. The catalyst is activated by treatment with carbon monoxide in the liquid phase. The reaction water is removed by excess reaction gas.

Abstract: The invention relates to an improved process for the preparation of polysuccinimide from maleic anhydride and ammonia, characterized in that the starting compounds are brought to reaction in liquid form in a tubular reactor with feed nozzle at temperatures of preferably 50.degree. C. to 500.degree. C. and residence times of preferably 0.1 to 600 seconds and the resulting reaction mixture is possibly further polymerized thermally in a high-viscosity reactor preferably continuously operated at 120.degree. C. to 300.degree. C.

Abstract: Ethylene glycol carbonate (EGC) can be obtained in purified form from contaminated material which contains impurities from the production or work-up process, by subjecting it to treatment with activated carbon. The treatment is carried out at 40.degree.-250.degree. C. and at 1-200 bar. The activated carbon has a BET surface area of 200-3,000 m.sup.2 /g.

Abstract: Reactors are described for the continuous reaction of gaseous substances on fixed bed catalysts with continuous temperature control and with the aid of a heat transport medium. These reactors are characterised by the design of the catalyst bed in the form of one or more regularly shaped sheet-like layers having a thickness of 0.01-50 cm, the surface of the catalyst layers being covered by a gas-permeable layer and this surface, on the starting material intake side and/or on the product outlet side, facing a likewise regularly shaped wall at a distance of 0.1 to 10 cm, which wall separates the space for the substances to be reacted or reacted substances from the space for the heat transport medium. The reactors are further characterised by the substances to be reacted being directed so as to flow through the catalyst bed approximately or completely perpendicularly to the sheet-like catalyst layers.

Abstract: Organic carbonates containing at least one aromatic ester group can be obtained in a continuous manner from carbonates containing at least one aliphatic ester group and a phenolic compound in the presence of a transesterification catalyst known per se by carrying out the reaction in at least two stirred containers connected one behind the other in such a way that, in each case, the phenolic compound is metered in liquid form into the first stirred container and the carbonate containing at least one aliphatic ester group is metered in liquid form into one or more of the stirred containers. The carbonate containing at least one aromatic ester group is removed in liquid form from the last stirred container. Volatile reaction products, for example alcohol which has been cleaved out or a dialkyl carbonate are removed in gaseous form from one or more stirred containers.

Abstract: Dialkyl carbonates can be prepared by reacting carbon monoxide with alkyl nitrites in a continuous gas phase reaction in the presence of a catalyst using a fixed bed reactor with a short catalyst bed in the direction of flow. The dialkyl carbonates are formed with almost quantitative selectivity; thermal decomposition of the alkyl nitrite, with the resulting formation of decomposition products, is not observed.

Abstract: A process is described for the catalytic preparation of propylene glycol carbonate (PGC) by reacting propylene oxide (POX) and CO.sub.2 in PGC as reaction medium at elevated temperature and elevated pressure and separating off from the catalyst the PGC formed. The process is carried out continuously under adiabatic temperature conditions. Per unit of time, PGC as reaction medium flows into the reactor at 7 to 350 times the amount of the PGC formed per unit of time. At all points of the reactor a CO.sub.2 excess is maintained over the other reaction partner POX. Of the effluent reaction mixture, 80 to 98% by weight are returned to the entrance of the reactor, while the remainder is worked up to give PGC. The sensible heat of the reaction product resulting from the adiabatic temperature conditions can be used for the work-up.

Abstract: C.sub.1 -C.sub.6 -Alkyl nitrites can be prepared by reacting nitrogen dioxide with C.sub.1 -C.sub.6 -alcohols, by, in a counterflow-operated column, feeding the alcohol or an alcohol/water mixture into the upper part of the column and the nitrogen dioxide or a nitrogen dioxide/inert gas mixture into the lower part of the column. The resulting alkyl nitrite is removed from the column as the top product and the co-formed nitric acid is removed from the column as the bottom product.

Abstract: The title compounds are prepared from organic carbonates having at least one aliphatic ester group and phenolic compounds by transesterification in the presence of a transesterification catalyst known per se at 60.degree.-320.degree. C. in a column-type reactor with multiple recycling of the reaction products into this reactor with intermediate storage of the product streams.

Abstract: A first alkanol having 1 to 3 C atoms or a mixture of this first alkanol with water or water itself can be separated off from oxygen-containing organic compounds having 3 to 7 C atoms from the group comprising second alkanols and dialkyl carbonates, which always have at least 2 C atoms more than the first alkanol, by permeation on membranes if a membrane obtained by plasma polymerization is employed.