Mechanistic Investigations of Aluminum Nitrite Assisted Aryl Nitrile Synthesis through C(sp3)–C(sp2) Bond Cleavage of Aryl Ketones

The C­(sp3)–C­(sp2) bond activation reactions of 1-phenyl-2-propanone are facilitated by in situ generated Al­(NO2)3 as an internal oxidant and the nitrogen source. The mechanistic investigations of formation of aryl nitrile from 1-phenyl-2-propanone are performed using density functional theory calculations at the CPCM/M06-2X/6-31G­(d,p) level with the conductor-like polarizable continuum model. The mechanistic pathway involves C–H bond cleavage and Beckmann fragmentation as the key steps in the formation of phenyl nitrile, and it also supports that Al­(NO2)3 is an active nitrite source instead of NaNO2. The C–H bond cleavage is found to be the rate-determining step with a kinetic isotope effect of 1, which is also validated by the energetic span model. The computational investigations are in good agreement with experimental results.