Abstract: A method is described for immediately terminating free radical polymerizations by adding an inhibitor solution comprising a phenothiazine compound and/or a monoalkyl ether of hydroquinone to the free radical polymerizing system. The method is characterized in that the solvent of the inhibitor solution comprises at least 50% by weight of the solvent of alkylene glycol and/or polyalkylene glycol and/or terminally etherified derivatives of alkylene glycol and/or of polyalkylene glycol. The method permits the use of nontoxic inhibitor solutions. Inhibitor solutions are also described which comprise a phenothiazine compound and/or a monoalkyl ether of hydroquinone and, as solvent, alkylene glycol and/or polyalkylene glycol and/or terminally etherified derivatives of these compounds.

Abstract: A method is described for the catalytic hydrogenation of aromatic nitro compounds with hydrogen to the corresponding amines in the presence of a supported catalyst comprising platinum. The method is characterized in that the catalyst comprising platinum has been modified with a tungsten compound and with a phosphorus compound in an oxidation state of <5. High yields and high selectivities are possible with the method.

Abstract: A method for hydrogenating optionally substituted phenols with one hydroxyl group to cyclohexanones over modified, palladium-comprising supported catalysts. This is possible surprisingly in selected alcoholic solvents with high selectivity. Here it is even possible to recycle the catalysts employed, which hitherto has only been possible with considerable loss of selectivity.