Transition Metal-Free Hydrogenolysis of Anilines to Arenes Mediated by Lithium Hydride

Yongli Cai; Wei Liu; Yang Yu; Ligao Liu; Qijun Pei; Han Wu; Teng He; Jianping Guo; Anan Wu; Ping Chen

doi:10.1021/jacs.2c05586

Transition Metal-Free Hydrogenolysis of Anilines to Arenes Mediated by Lithium Hydride

J Am Chem Soc. 2022 Sep 28;144(38):17441-17448. doi: 10.1021/jacs.2c05586. Epub 2022 Sep 15.

Authors

Yongli Cai^{1

2}, Wei Liu³, Yang Yu¹, Ligao Liu³, Qijun Pei¹, Han Wu^{1

2}, Teng He^{1

2}, Jianping Guo^{1

2}, Anan Wu³, Ping Chen^{1

2}

Affiliations

¹ Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China.
² University of Chinese Academy of Sciences, Beijing 100049, China.
³ Department of Chemistry, College of Chemistry and Chemical Engineering, Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, Xiamen University, Xiamen 361005, China.

PMID: 36109500
DOI: 10.1021/jacs.2c05586

Abstract

Hydrodenitrogenation (HDN) of nitrogen-containing organic compounds such as aniline and its derivatives is of scientific interest and practical importance. Major efforts have been devoted to the development and understanding of transition metal-mediated chemical processes. Herein, we report a fundamentally different strategy using a transition metal-free material, that is, lithium hydride (LiH) enabling the hydrogenolysis of aniline to benzene and ammonia via a chemical looping approach. Aniline reacts with LiH to form lithium anilide, and subsequently, the hydrogenolysis of lithium anilide yields benzene and ammonia and regenerates LiH to complete the loop. This LiH-mediated chemical looping HDN process stands in sharp contrast to the transition metal-catalyzed or -mediated processes, which commonly lead to the complete hydrogenation of aromatic rings. A highly denitrogenated product formation rate of 2623 μmol·g^-1·h^-1 is achieved for the hydrogenolysis of lithium anilide at 300 °C and 10 bar H₂, which exceeds the catalytic rate of transition metal catalysts. Computational studies reveal that the scission of C-N bonds is facilitated by a Li-mediated nucleophilic attack of hydride to the α-sp²C atom of aniline. This work not only provides a distinctive chemical looping route for HDN, but also opens up materials space for the denitrogenation of anilines.