A process for the preparation of indole-2-carboxylic acid
By using the condensation reaction of o-nitrotoluene, diethyl oxalate, and sodium ethoxide in ethanol solution, and controlling the azeotropic removal of ethanol in an aqueous system, combined with the use of PVPK30 and KCl, the problems of environmental pollution and separation difficulties in the production of indole-2-carboxylic acid have been solved, achieving high-yield and high-purity production of indole-2-carboxylic acid, which is suitable for industrial application.
CN122103003APending Publication Date: 2026-05-29ZHEJIANG HORVAR PHARM CO LTD
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- ZHEJIANG HORVAR PHARM CO LTD
- Filing Date
- 2026-02-05
- Publication Date
- 2026-05-29
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Abstract
The application discloses a synthesis method of indole-2-carboxylic acid, which is suitable for industrial production and comprises the following steps: (1) condensation: mixing o-nitrotoluene, diethyl oxalate and sodium ethoxide ethanol solution, raising to 75-85 DEG C and reacting for 1.5-3 hours, adding into water, stirring for 0.5-1.5 hours, removing ethanol, decoloring, filtering, adjusting the pH of the filtrate to 1-2, and obtaining an intermediate; (2) reduction: adding methanol to the intermediate, adding Raney nickel, raising to 55-65 DEG C, adding hydrogen and reacting, lowering to room temperature, filtering, removing methanol, lowering to 0-5 DEG C and preserving for 1-2 hours, and filtering to obtain a crude product; and (3) purification: adding water to the crude product, adjusting the pH to 8-9, decoloring, filtering, adjusting the pH to 2-3, precipitating a solid, filtering, and drying the filter cake.
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