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Aus O wird N: Die erste homogen katalysierte Diaminierung primärer und sekundärer Diole mit Ammoniak liefert die entsprechenden Diamine. Auch primäre und sekundäre Alkohole einschließlich hydroxysubstituierter Ester werden effizient in primäre Amine überführt. Dieses atomeffiziente und selektive Aminierungsverfahren läuft in einer Ammoniakatmosphäre ohne zusätzliche Wasserstoffquellen ab.

The use of polyaniline (PANI) as catalyst support for heterogeneous catalysts and their application in chemical catalysis is hitherto rather poorly known. We report the successful synthesis of highly dispersed PANI-supported platinum catalysts (particle sizes between 1.7 and 3.7 nm as revealed by transmission electron microscopy, TEM) choosing two different approaches, namely (i) deposition-precipitation of H 2 PtCl 6 onto polyaniline, suspended in basic medium (DP method) and, (ii) immobilization of a preformed nanoscale platinum colloid on polyaniline (sol-method). The PANI-supported platinum catalysts were applied in the selective hydrogenation of the a,b-unsaturated aldehyde citral. In order to benchmark their catalytic performance, citral hydrogenation was also carried out by using platinum supported on the classical support materials silica (SiO 2 ), alumina (Al 2 O 3 ), active carbon and graphite. The relations of the structural characteristics and surface state of the catalysts with respect to their hydrogenation properties have been probed by EXAFS and XPS. It is found that the DP method yields chemically prepared PtO 2 on polyaniline and, thus, produces a highly dispersed and immobilized Adams catalyst (in the b-PtO 2 form) which is able to efficiently hydrogenate the conjugated C=C bond of citral (selectivity to citronellal = 87%), whereas reduction of the C=O group occurs with polyanilinesupported platinum (selectivity to geraniol/nerol = 78%) prepared via the sol-method. The complete reversal of the selectivity between the preferred hydrogenation of the conjugated C=C or C=O group is not only particularly useful for the selective hydrogenation of a,b-unsaturated aldehydes but also unveils the great potential of conducting polymer-supported precious metals in the field of hitherto barely investigated chemical catalysis.

Hydr-) oxidic PdO x H y colloids were prepared by H 2 PdCl 4 hydrolysis in presence of poly(vinylpyrrolidone) under pH control. After immobilization, the resulting catalysts show a high chemo-and stereo selectivity in the hydrogenation of C-C triple bonds. Systematic investigations of the preparation parameters indicate that the hydrolysis pH, the PVP amount and chainlength as well as the colloid aging time are of major importance for catalytic performance.