Figure 1 The amidation of phenylacetic acid with benzylamine catalysed by nickel metal; Figure 2 The yield of direct amidation with recycle catalysts; Table 1 Optimization of the reaction conditions using different solvents ; Table 2 Synthesis of amide derivatives from carboxylic acids and amines using NiCl2 as catalyst;The original spectra for all compouds from Direct amidation of non-activated phenyl acetic acid and benzyl amine derivatives catalysed by NiCl<sub>2</sub>

Figure 1 showed the performance of different nickel catalysts used for the amidation of phenylacetic acid and benzylamine in toluene at 110℃. And the catalytic activities of the different nickel catalysts were NiCl2>DPPE·NiCl2>(CH3COO)2Ni>Ni(acac)2>DPPP·NiCl2>NiCl2(Pph3)2>NiCl2·6H2O>none. ;Catalyst recyclability is an essential aspect of the green chemistry. Our best-performance direct amidation catalyst NiCl2 was found to be equally effective from fresh up to the 3rd and 3th cycle without significant loss of activity as showed in Figure 2. In the fourth cycle, the yield decreased obviously because of the loss of the catalyst. ;The influences of different solvents and reaction time on the direct amidation of phenylacetic acid with benzylamine catalysed by NiCl2 were investigated (Table 1). And from Table 1.;With the above knowledge in hand, we investigated the acid 1 and benzylamine 2 scopes of the NiCl2-catalysed direct amidation protocol at the same reaction condition. And the results showed in Table 2.;The original hydrogen spectra, carbon spectra and the mass spectra for all compounds