ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

The Cu(I)- and HNO₃-catalyzed oxidation of substituted toluenes to the benzoic acid based on NO _x recycling

Mengyi Wei, Chao Qian, and Xinzhi Chen

Zhejiang University, Zhejiang, China

E-mail: qianchao@zju.edu.cn

Abstract: Based on the recycling of NO _x , the Cu(I)- and HNO₃-catalyzed oxidation of 2-chloro-4-(methylsulfonyl)toluene to 2-chloro-4-(methylsulfonyl)benzoic acid has been developed with an excellent yield of 84.2% and a purity of 99.7%. The optimized reaction conditions (160 °C, oxygen pressure 1.5 MPa, HNO₃ concentration 25 wt%, HNO₃: substrate 0.5:1) use 1.0 mol% CuI as catalyst. The dosage of HNO₃ in the new process is only 25% of the stoichiometric amount and 12.5% of the amount of the traditional process. The NO _x emission is 5% amount of the traditional process. The oxidation of several additional toluene derivatives with comparable yields demonstrates the generality to these reaction conditions.

Keywords: HNO₃-catalyzed oxidation ; NO_x recycling ; Benzylic oxidation ; 2-Chloro-4-(methylsulfonyl)benzoic acid 

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-017-0256-y

Chemical Papers 72 (1) 51–56 (2018)