Indexed on: 09 Mar '16Published on: 18 Feb '16Published in: Organic Process Research & Development
An environmental friendly approach for two-step synthesis of hexanitrostilbene (HNS) has been studied here. In the first step from trinitrotoluene (TNT) to hexanitrobienzyl (HNBB), commercial NaClO was employed as oxidant in mixed solvent of ethyl acetate/ethanol (0.25 mL/1.25 mL per mmol of TNT) instead of benzene/ethanol. In the second step from HNBB to HNS, 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)/FeCl2 was used as an effective catalytic system with O2 in DMSO solvent. A complex of metal ion and O2 [M(n+1)OO•] was supposed to be the active agent, and TEMPO itself was difficult to initiate dehydrogenation of HNBB but could promote the catalytic cycle of complex M(n+1)OO•. Finally, we increased the scale from 30 to 1000 g to investigate the feasibility of production. The total yield of two steps would be unprecedentedly as high as 70%.