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Clean production process for continuously synthesizing hydantoin

A clean production and chemical synthesis technology, applied in organic chemistry and other directions, can solve the problems of difficult to suppress side reactions, difficult to recover and apply ammonia and carbon dioxide, and achieve increased intermolecular contact opportunities, high yield and high purity, and low solubility. Effect

Inactive Publication Date: 2020-09-01
龙智
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The above method also has the problems that excessive ammonia and carbon dioxide are difficult to recycle and apply mechanically, and the side reactions are difficult to suppress.

Method used

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  • Clean production process for continuously synthesizing hydantoin

Examples

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Comparison scheme
Effect test

Embodiment 1

[0043] Example 1: Ammonia, carbon dioxide and water are prepared in a molar ratio of 1:1:12 to prepare an aqueous solution of carbon dioxide and ammonia. The feed flow rate is 390kg / h, which is preheated to 80°C by a preheater, and 44wt% of the feed flow rate is 63.5kg / h The concentrated hydroxyacetonitrile solution is quickly mixed in a static mixer, enters three column reactors in series from the bottom, reacts at a pressure of 4.5MPa and a temperature of 70-100°C for 2.5h to obtain hydantoin synthetic liquid, and then flows out from the top of the reactor Enter the quencher; the operating pressure of the quencher is 0.8MPa, the gas phase separated by flash evaporation is removed from the carbon dioxide and ammonia recovery system, the liquid phase enters the stripping tower, and the carbon dioxide and ammonia remaining in the liquid phase are extracted under negative pressure and ≤100°C into the gas phase Removal of carbon dioxide and ammonia recovery system; the liquid phas...

Embodiment 2

[0046] Example 2: Ammonia, carbon dioxide and water are prepared in a molar ratio of 1:1.15:15 to prepare an aqueous solution of carbon dioxide and ammonia. The feed flow rate is 4200kg / h, which is preheated to 90°C by a preheater, and the feed flow rate is 590kg / h with a concentration of 40wt%. The hydroxyacetonitrile solution was quickly mixed in a static mixer, and entered into 5 tube-bundle reactors connected in series from the bottom, reacted at a pressure of 4.0 MPa and a temperature of 80-105°C for 3.5 hours to obtain hydantoin synthetic liquid, and then flowed out from the top of the reactor into Quench cooler; the operating pressure of the quencher is 1.3MPa, the gas phase of the flash separation is removed from the carbon dioxide and ammonia recovery system, the liquid phase enters the stripping tower, and the residual carbon dioxide and ammonia in the liquid phase are extracted under the conditions of negative pressure and ≤100°C into the gas phase to remove Carbon d...

Embodiment 3

[0049] Example 3: Ammonia, carbon dioxide and water are prepared in a molar ratio of 1:1.2:15 to prepare an aqueous solution of carbon dioxide and ammonia. The feed flow rate is 4250kg / h, preheated to 90°C by a preheater, and the feed flow rate is 670kg / h with a concentration of 38wt%. The hydroxyacetonitrile solution was quickly mixed in a static mixer, and entered from the bottom into a composite reactor consisting of five series-connected column reactors and tube bundle reactors, and reacted at a pressure of 5.5 MPa and a temperature of 80-105°C for 4 hours to obtain hydantoin The synthetic liquid then flows out from the top of the reactor into the quencher; the operating pressure of the quencher is 1.5MPa, the gas phase of the flash separation is removed from the carbon dioxide and ammonia recovery system, the liquid phase enters the stripping tower, and the liquid is extracted under negative pressure and ≤100°C The carbon dioxide and ammonia remaining in the phase enter th...

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Abstract

A clean production process for continuously synthesizing hydantoin comprises the following steps: preheating a carbon dioxide ammonia water solution prepared from an ammonia source, a carbon source and water, mixing with hydroxyacetonitrile, continuously synthesizing, carrying out reduced pressure flash evaporation, carrying out gas stripping, concentrating, acidifying, crystallizing, separating to obtain a crude hydantoin product, and refining to obtain the high-purity hydantoin product. A carbon dioxide and ammonia recovery system sequentially absorbs the gas phase separated by gas strippingand reduced pressure flash evaporation to obtain a carbon dioxide ammonia water solution, and the carbon dioxide ammonia water solution returns to a reaction system. By increasing the amount of carbon dioxide in the ratio, side reactions generating iminodiacetonitrile, nitrilotriacetonitrile and glycine are restrained, and the hydantoin yield is increased; and through timely release of each gas phase in the system and reasonable arrangement of a recovery sequence, the difficulty of recycling carbon dioxide and ammonia in the system is reduced, the loss of carbon dioxide and ammonia is reduced, zero discharge of wastewater and waste liquid can be realized, and the method is an environment-friendly and clean hydantoin production process method.

Description

technical field [0001] The invention relates to a clean production process for continuously synthesizing hydantoin by using hydroxyacetonitrile as a raw material, belonging to the field of fine chemical intermediates. Background technique [0002] Hydantoin, also known as hydantoin and 2,4-imidazolidinedione, is an important basic organic raw material widely used in pesticide and pharmaceutical industries. [0003] The main production methods of hydantoin are glycine method and hydroxyacetonitrile method. [0004] The glycine method uses glycine, sodium hydroxide and urea as raw materials, absorbs and neutralizes hydantoin through sulfuric acid, and produces ammonium sulfate and sodium sulfate as by-products. The production cost of this method is high, a large amount of low-value inorganic salts are produced by-product, and the hydantoin product has low purity. [0005] The hydroxyacetonitrile method uses hydroxyacetonitrile, ammonium carbonate, ammonium bicarbonate or amm...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07D233/72
CPCC07D233/72
Inventor 龙智李宽义曾雯娟
Owner 龙智
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