Process for preparing p-fluoro thiophenol

Abstract

The one-pot process of preparing p-fluoro thiophenol includes the following steps: reaction between fluorobenzene and chlorosulfonic acid to produce p-fluorophenyl sulfuryl chloride, and adding icy water to lower the temperature to 0-40 deg.c; and adding zinc powder to the reactor for direct reduction in two stages, including the first stage at 0-50 deg.c for 1-4 hr and the second stage at 70-95 deg.c for 1-4 hr. The one-pot process completes the chrlorosulfonation and reduction in one reactor, needs no filtering separation, and has short technological process, less apparatus used, saving in material, less exhaust, low cost and easy industrial application.

Description

technical field [0001] The invention belongs to the production method of organic compounds, and particularly proposes a method for preparing p-fluorothiophenol in one pot. Background technique [0002] p-Fluorothiophenol is an important medicine, pesticide and polymer intermediate, and can also be used in the detection of chemiluminescent agents and the preparation of nonlinear optical materials. [0003] The existing synthetic method is basically to prepare p-fluorobenzenesulfonyl chloride by sulfonyl chlorination of fluorobenzene, add water to dilute, filter and separate p-fluorobenzenesulfonyl chloride, and then reduce p-fluorobenzenesulfonyl chloride to obtain p-fluorobenzenethiol . The sulfonyl chlorination agent is chlorosulfonic acid, and the reducing agent is sodium borohydride or zinc powder. The specific processes are: [0004] SO 2 Reaction method: in the US 5659088 technology disclosed by Bayer, p-fluorobenzenesulfonyl chloride...

AI Technical Summary

Problems solved by technology

However, the dilution process after the two-pot method of sulfonyl chlorination can produce a large amount of waste acid, which is not fully utilized in production, causing environmental discharge pollution; the chlorosulfonation reaction is carried out in a reactor, and after the chlorosulfonation is completed, the Pour the reaction mixture into ice water to dilute and precipitate, filter, then add the prepared sulfuric acid and p-fluorobenzenesulfonyl chloride filter cake in another reduction pot, and then add zinc powder for reduction

The method uses two reactors for chlorosulfonation and reduction, and a filter device is needed in the middle, so that the process route is long and the equipment investment is large; after chlorosulfonation, dilution and filtration discharge a large amount of waste acid, and the reduction stage consumes new sulfuric acid again. As a result, more wastewater is discharged and raw material consumption is greater