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

An alternative synthetic process of p-acetaminobenzenesulfonyl chloride through combined chlorosulfonation by HClSO₃ and PCl₅

Shiyu Tan, Yang Yang, Ziping Luo, Shuo Zhao, Dafu Huang, Jun Zhang, Lichun Dong, and Gang Wang

School of Chemistry and Chemical Engineering, Chongqing University, 400044 Chongqing, China

E-mail: lcdong72@gmail.com

Abstract: p-Aminobenzene sulfonamide (sulfanilamide, SN) is the simplest and most-used sulfonamide medicine. The key step of SN production via the commonly used chlorosulfonic acid routine is the synthesis of p-acetaminobenzenesulfonyl chloride (P-ASC). A large amount of HSO₃Cl has to be used in the traditional process, which results in serious environmental problems. In this study, an alternative chlorosulfonic acid process to synthesize P-ASC was investigated by partially substituting HSO₃Cl by PCl₅ as the chlorination agent. Compared with the traditional process, the molar ratio of HSO₃Cl to acetanilide (the main raw material) can be decreased from 4.96 to 2.1 using CCl₄ as the diluent; also, addition of a small amount of NH₄Cl was found to significantly increase the P-ASC yield. Operating conditions of the reaction were studied first by single-factor experiments and later by orthogonal experiments to obtain optimum operating conditions under which the P-ASC yield can reach as high as 86.3 %.

Keywords: p-aminobenzene sulfone chloride – chlorosulfonation process – HSO3Cl – PCl5 – p-aminobenzene sulfonamide

Full paper is available at www.springerlink.com.

DOI: 10.2478/s11696-011-0026-1

Chemical Papers 65 (4) 510–518 (2011)