Method for preparation of 2, 5-dichloronitrobenzene by continuous nitration

Abstract

The invention discloses a method for preparation of 2, 5-dichloronitrobenzene by continuous nitration. The method comprises the steps of: adopting three-stage kettle type continuous reaction, adding sulfuric acid, nitric acid and p-dichlorobenzene in an extraction kettle into a first stage nitrification kettle simultaneously to carry out nitrification reaction, letting nitrification liquid enter a next stage nitrification kettle through self-carried raisers of all nitrification kettles in order to react, at the end of reaction in a third stage nitrification kettle, separating an oil phase and an acid phase, carrying out neutralization, washing and dehydration on the oil phase so as to obtain 2, 5-dichloronitrobenzene, internally recycling part of waste acid in the acid phase back to the first stage nitrification kettle, letting the residual waste acid enter an extraction kettle, and performing p-dichlorobenzene extraction, and then conducting separation to obtain acidic p-dichlorobenzene and extracted waste acid, concentrating the extracted waste acid into concentrated sulfuric acid, and making the concentrated sulfuric acid and acidic p-dichlorobenzene enter the first stage nitrification kettle for recycling. The method provided by the invention adopts automation control, cancels a mixed acid preparation procedure, simplifies the technological process, can realize continuous nitrification reaction, continuous nitrification liquid separation and continuous waste acid extraction.

Description

technical field [0001] The invention belongs to the field of synthesis of 2,5-dichloronitrobenzene, and relates to a method for preparing 2,5-dichloronitrobenzene through continuous nitration. Background technique [0002] 2,5-Dichloronitrobenzene is an important chemical intermediate, mainly used in the production of 2,5-dichloroaniline, scarlet-based GG, red-based 3GL, red-based RL and trichloronew (2,4,4 - trichloro-2-hydroxydiphenyl ether), etc., in addition, it can also be used as a nitrogen fertilizer synergist to increase rice yield. [0003] At present, the industrialized production of 2,5-dichloronitrobenzene adopts a batch production process, using sulfuric acid as the base acid, adding p-dichlorobenzene, then adding nitric acid and sulfuric acid mixed acid for nitration, neutralization, washing, and dehydration to obtain 2,5-dichloronitrobenzene. 5-dichloronitrobenzene products. The batch production process has a series of problems such as low production capacit...

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Problems solved by technology

[0005] Aiming at the problems that the current 2,5-dichloronitrobenzene production process is not fully continuous, the waste acid circulation is large, and there is an emulsified layer at the interface of the oil phase and the acid phase, the invention provides a continuous nitration to prepare 2,5-dichloronitrobenzene The method of nitrobenzene adopts continuous nitration to prepare 2,5-dichloronitrobenzene. This method adopts automatic control, cancels the mixed acid preparation process, simplifies the process flow, and can realize continuous nitration reaction, continuous separation of nitration liquid and Continuous waste acid extraction

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