Hydrogenation of nitroaromatics containing a carbonyl group catalyzed by the palladium complex of MgO-supported melamino-formaldehyde polymer

Abstract

The palladium complex of MgO‐supported melamino–formaldehyde polymer was prepared for the first time, and its catalytic behaviors for the hydrogenation of nitroaromatics containing a carbonyl group were examined. It was found that the nitro and carbonyl groups in p‐nitrobenzaldehyde can be sequentially hydrogenated to form the corresponding p‐aminobenzaldehyde (or its self‐condensation product) and to form p‐aminobenzyl alcohol (or the self‐condensation that followed the reduction product). Under the same conditions, only the nitro group is selectively hydrogenated in o‐nitrobenzaldehyde and p‐nitroacetophenone with the carbonyl group remained to form the corresponding aminoaromatic compound. Although only the nitro group is selectively hydrogenated also in m‐nitrobenzaldehyde, the product is not the corresponding amino compound owing to the too slow hydrogenation rate and the strong tendency of self‐condensation. The hydrogenation rate is in the order of p‐nitroacetophenone >­p‐nitrobenzaldehyde > o‐nitrobenzaldehyde > m‐nitro‐­benzaldehyde. Copyright © 1999 John Wiley & Sons, Ltd.

Facile Synthesis of Monodisperse Noble‐Metal Nanoparticles and High Catalytic Performance for Organic Reactions in Both Water and Oil Systems

“…Typically, gold, [1][2][3][4][5][6][7] silver, [7][8][9][10] palladium, [11][12][13][14][15][16][17][18] and platinum nanoparticles [19][20][21] and their bimetals [22][23][24][25] show good performance in catalysis of Suzuki, [26] Heck, [27] and Stille cross-coupling reactions, [28] in addition to aerobic oxidation [29] and hydrogenation of nitroaryl compounds. [30][31][32][33][34][35][36][37][38][39][40][41] Monodisperse noble-metal nanoparticles have been synthesized through reduction of their corresponding soluble salts under reflux conditions [42] or decomposition of organometallic precursors in oil phase at high temperatures. [43] Nanoparticles obtained by these routes can be well controlled, with tunable size, and the nanoparticles are also uniformly disperse, making them potential candidates for catalysis in various oil phases.…”