Abstract: Diaryl carbonates can be prepared by reacting aromatic hydroxy compounds with CO and O.sub.2 at elevated temperature over a noble metal catalyst in the presence of a base, a quaternary salt, a cocatalyst and a dessicant. According to the invention, the noble metal catalyst is activated with CO in the presence of the quaternary salt and optionally in the presence of the cocatalyst. In a particular process variant, the base used is a preformed alkali metal phenoxide.

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: This invention provides a process for the purification of diphenyl carbonate (DPC) from crude products of diphenyl carbonate production. In this process, crude products are used that have a distillable fraction consisting of over 70 wt. % diphenyl carbonate and are fractionally crystallised from the melt (fractionating melt crystallisation).

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: A process is described for preparing aromatic carbonates by transesterification of aliphatic carbonates with phenolic compounds in the presence of titanium compounds known per se, in which, before work-up, the transesterification mixture is cooled to a temperature below 120.degree. C., during which the mixture must remain liquid, the titanium-containing precipitate which is deposited is separated off, and the aromatic carbonate is then obtained by methods which are conventional per se.

Abstract: A process is described for the preparation of dialkyl carbonates by oxidative carbonylation of the corresponding alcohol in the presence of a copper-containing catalyst at elevated temperature and elevated pressure, which process permits simple separation of the copper-containing catalyst by sedimentation, and of the reaction water in the case of methanol by simple distillation from the reaction solution.