Abstract: In a process for the preparation and the isolation of p-hydroxybenzonitrile (HBN), in which a p-halogenated phenol is reacted with cuprous cyanide in a suitable solvent, the reaction mixture obtained after the reaction of the p-halogenated phenol with cuprous cyanide has been substantially completed is contacted with an aqueous solution of a bromide salt and, optionally, an organic diluent, the aqueous and organic phases are separated, HBN is distilled out from the organic phase, an alkali metal cyanide is added to the aqueous phase and CuCN is filtered off from the resulting aqueous phase.

Abstract: In a process for the preparation and the isolation of p-hydroxybenzonitrile (HBN), in which a p-halogenated phenol is reacted with cuprous cyanide in a suitable solvent, the reaction mixture obtained after the reaction of the p-halogenated phenol with cuprous cyanide has been substantially completed is contacted with an aqueous solution of a bromide salt and, optionally, an organic diluent, the aqueous and organic phases are separated, HBN is distilled out from the organic phase, an alkali metal cyanide is added to the aqueous phase and CuCN is filtered off from the resulting aqueous phase.

Abstract: A process for the preparation of Decabromodiphenyl ether is disclosed, which employs dibromomethane as the reaction medium, at temperatures not exceeding 80.degree. C.The product obtained by the process of the invention possesses improved thermal stability.

Abstract: A process for the preparation of decabromodiphenyl ether by the reaction of diphenyl ether or of a partially brominated derivative thereof, in a mixture of halogenated organic solvents is described.The process of the invention provides a product having improved thermal stability. The process can be carried out in a quasi-steady state manner, thereby producing a product with constant quality.