A method for preparing 2-nitro-5-cyanothiobenzoic acid

By generating an intermediate from 5-amino-2-nitrobenzoic acid with a nitrosating agent and reacting it with a thiocyanating agent, the problems of high cost, high toxicity, and poor atom economy in existing technologies have been solved, achieving a safe, environmentally friendly, and low-cost preparation of 2-nitro-5-cyanothiobenzoic acid.

CN122079838APending Publication Date: 2026-05-26BEIJING J&K SCI
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Patent Information

Application Number
CN202511993437.4
Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
Filing Date
2025-12-26
Publication Date
2026-05-26

AI Technical Summary

Technical Problem

The existing synthetic route for 2-nitro-5-cyanothiobenzoic acid is costly, has poor atom economy, uses highly toxic cyanide, and has poor operational safety.

Method used

5-Amino-2-nitrobenzoic acid is reacted with a nitrosating agent at a specific temperature to generate the intermediate 3-carboxy-4-nitrophenyl diazonate, which is then subjected to a nucleophilic substitution reaction with a thiocyanating agent under mild conditions to prepare 2-nitro-5-cyanothiobenzoic acid. Non-toxic thiocyanating agents such as cuprous thiocyanate and sodium thiocyanate are used.

Benefits of technology

The preparation of 2-nitro-5-cyanothiobenzoic acid was achieved safely, environmentally friendly, and at low cost, with high product quality and high yield, making it suitable for industrial production.

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Abstract

This invention relates to a method for preparing 2-nitro-5-cyanothiobenzoic acid, comprising: (1) dissolving 5-amino-2-nitrobenzoic acid and an acid in a first reaction solvent, water, adding a nitrosating agent dropwise to the reaction system, reacting at a temperature of -20 to 20°C for 1 to 12 h, to obtain intermediate 3-carboxy-4-nitrobenzene diazonate M; the first reaction solvent is one or a mixture of water, acetonitrile, and ethanol; (2) reacting the intermediate 3-carboxy-4-nitrobenzene diazonate M obtained in step (1) with a thiocyanating agent and a catalyst in a second reaction solvent to undergo a nucleophilic substitution reaction, reacting at a temperature of -20 to 30°C for 1 to 24 h, to obtain 2-nitro-5-cyanothiobenzoic acid; the thiocyanating agent is selected from one or a mixture of cuprous thiocyanate, sodium thiocyanate, or potassium thiocyanate; the second reaction solvent is one or a mixture of water, acetonitrile, and ethanol. The raw materials of this invention are readily available, the cost is controllable, the reaction is mild, it is green and environmentally friendly, and it has high selectivity and high yield.
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