Cycle recovery method of formic acid solvent in metronidazole production process

A production process, recycling technology, applied in the separation/purification of carboxylic acid compounds, organic chemistry, etc.

Active Publication Date: 2015-07-15
GUANGZHOU OUHUA PHARMA
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Some chemical companies directly discharge dilute formic acid as waste water, causing environmental pollution

Method used

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  • Cycle recovery method of formic acid solvent in metronidazole production process

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Embodiment Construction

[0019] When implementing the present invention, first add dilute phosphoric acid to the dehydration kettle 19, open the heating medium outlet valve 17 and the heating medium inlet valve 18, and remove the moisture in the dilute phosphoric acid by heating; Phosphoric acid becomes polyphosphoric acid; then the phosphoric acid valve 11 is opened to allow viscous polyphosphoric acid to flow into the packing layer, absorb water while flowing downward, and finally flow into the phosphoric acid storage tank 7. Then add an appropriate amount of hydroxylated liquid to the evaporator 1, and then open the heating steam valve 5 and the cooling water inlet valve 14 in sequence. Later, the hydroxylated liquid in the evaporator 1 boils, and the generated steam rises to the packing layer 21 to remove solid entrainment, and then enters the bottom of the water absorption tower 8 from the connecting pipe 6 . During the flow of the steam in the water absorption tower 8, the moisture is absorbed b...

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Abstract

The invention belongs to a recovery method of dilute formic acid, especially relates to the cycle recovery method of a formic acid solvent in a metronidazole production process. The cycle recovery method is characterized by comprising the following technological process: (1) heating a dewatering kettle, and removing water in dilute phosphoric acid, to obtain viscous polyphosphoric acid; (2) pressing the viscous polyphosphoric acid into the top of a water absorption tower, diluting, then flowing downwards along a filler layer, next gradually turning into dilute phosphoric acid, and flowing into a dilute phosphoric acid storage kettle; (3) sending the dilute phosphoric acid to the dewatering kettle by a pump; (4) evaporating to obtain dilute formic acid steam with the mass concentration of 20-80%; (5) allowing the formic acid steam to firstly pass through a filler layer of an evaporator, and removing solid entrainments in the formic acid steam; (6) then removing water in the formic acid steam through the water absorption tower having the viscous polyphosphoric acid; and (7) condensing the formic acid steam after concentration into a high-concentration formic acid liquid. The cycle recovery method can be widely applied for dewatering recovery of a large number of produced dilute formic acid solution in chemical production enterprises.

Description

1. Technical field [0001] The utility invention belongs to a method for recovering dilute formic acid, in particular to a method for recycling a formic acid solvent in the production process of metronidazole. 2. Background technology [0002] Metronidazole is a highly effective anti-trichomoniasis, and can also treat various types of amebiasis, acne and rosacea. It has the characteristics of remarkable curative effect, few strains of antibacterial drugs, and easy absorption and distribution of various routes of administration. It is regarded as the drug of choice for anti-anaerobic bacteria by the World Health Organization (WHO). [0003] The method for synthesizing metronidazole that has been reported so far is: dissolving 2-methyl-5-nitroimidazole in formic acid solvent, adding ethylene oxide and sulfuric acid successively, and reacting to obtain a hydroxylated solution. Heating and evaporating the hydroxylation solution to obtain dilute formic acid aqueous solution, then...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C53/02C07C51/42
Inventor 曾舟华徐振强陈文王海南谢玉桥
Owner GUANGZHOU OUHUA PHARMA
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