Reduction alumina-supported hydrazine

Vass, A., Dudas, J., T6th, J. and Varma, R.S., Solvent-free reduction of aromatic nitro compounds with alumina-supported hydrazine under microwave irradiation, Tetrahedron Lett., 2001, 42, 5347-5349. 

Reduction of Aromatic Nitro Compounds to Amines with Alumina-supported Hydrazine... 

Scheme 8.60. Reduction of nitro compounds to amines with alumina-supported hydrazine.

A combination of iron(III) salts with solid-supported hydrazine hydrate (preabsorbed on AI2O3) were successfully used in reductions of aromatic nitro groups (Scheme 4.33). The nature of the solid support plays a crucial role in this reaction and alumina was found to be most effective. In the absence of a solid support, the reaction... 

Bezverkhyy and coworkers [44] from the IRC in Lyon have studied the preparation of alumina-supported M0S2 via RDP. Starting from an aqueous solution of ammonium tetrathiomolybdate, (NH4)2MoS4, reduction to deposit M0S2 onto the suspended alumina was brought about by hydrazine, N2 H4. 

Ruthenium catalysts, supported on a commercial alumina (surface area 155 m have been prepared using two different precursors RUCI3 and Ru(acac)3 [172,173]. Ultrasound is used during the reduction step performed with hydrazine or formaldehyde at 70 °C. The ultrasonic power (30 W cm ) was chosen to minimise the destructive effects on the support (loss of morphological structure, change of phase). Palladium catalysts have been supported both on alumina and on active carbon [174,175]. Tab. 3.6 lists the dispersion data provided by hydrogen chemisorption measurements of a series of Pd catalysts supported on alumina. is the ratio between the surface atoms accessible to the chemisorbed probe gas (Hj) and the total number of catalytic atoms on the support. An increase in the dispersion value is observed in all the sonicated samples but the effect is more pronounced for low metal loading. 

In order to increase the ultrasound effects, the reduction of all the samples was performed with hydrazine at 80°C for 20 min undertaking the solid-liquid suspension at a sonication of frequency 21 kHz and power 30 W, calculated with the calorimetric method [7]. This particular power was chosen in order to minimize the possible effects of destruction of the support in fact the transformation of the alumina in fine powder, loosing the morphological structure was observed increasing the power just at 45 W. A change in the alumina phase (usually from n to a phase) was also detected in similar condition at room temprature [8],... 

Hydrogenation is the most well studied area among immobilized palladium catalysis. While a great majority of the applications focused on the use of support such as alumina and activated carbon, a great diversity of novel support systems have been reported in recent years, aimed at finding a catalyst with a well-characterized coordination sphere and tailor-made activity. Pd(0) catalysts dispersed on crosslinked styrene-divinylbenzene copolymers have been prepared by impregnation of lipophilic complexes followed by reduction with hydrazine. It was found that the functional groups in the polymer as well as polymer particle sizes had a major effect on catalyst activity.t [i53]-[i95]... 

---