Involving Palladium Research Articles

Nitration of benzenoid compounds by palladium salts and by nitrogen dioxide

The nitration of benzenoid compounds by palladium nitrate and by a mixture of palladium acetate and sodium nitrite has been studied under a variety of conditions. The latter system yields nitrobenzene semi-catalytically in chloroacetic acid at 100°(ca. 1200% in an oxygen atmosphere), with relatively little by-product (ester) formation. The use of nitrogen dioxide in place of sodium nitrite results in a fully catalytic system. Observations which bear on the mechanisms are discussed. Aromatic nitration has also been effected in good yield by passing nitrogen dioxide into a solution of the aromatic compound in trifluoroacetic acid. In contrast to the reactions involving palladium(II), this is almost certainly an SE2 process involving the nitronium ion.

The Rhodium(III) Complexes of Aspartic and Glutamic Acids

The chelating tendencies of the alpha amino acids with platinum group metal ions are well known; with the dibasic acids, complexes have been reported involving palladium (II) and platinum (II) with both aspartic and glutamic acids. There is no mention of the successful synthesis of complexes between these acids and rhodium (III), however. This communication reports a method of preparation for these two complexes as well as an alternative method for the synthesis of the palladium (II) complex with aspartic acid. It is shown that the mole ratio of rhodium (III) to aspartate or glutamate is one to three, that the ligands act as bidentates, and that the aspartic acid complex. Infrared and elemental analytical data are given.