The gaseous addition-diketonization mechanism of aniline and phenylacetylene: A theoretical investigation

The addition-diketonization mechanism of aniline and phenylacetylene activated with O2, CuBr2 and 2,2,6,6-tetramethylpiperadine-1-oxyl (TEMPO) were elucidated at B3LYP/6-31G(d,p) level with Gaussian 03 package. It is found that the C–H bond scission bears the lowest energy barrier, but the barrier of the succedent H-shifting process is too large to overcome. However, TEMPO can accept the dissociated hydrogen atom, and the generated TEMPOH will aid the H-shifting process and the O–O breakage. It may be TEMPOH that makes the diketonization energetically favorable, rather than TEMPO.