Production method for preparing N,N'-dicyclohexylcarbodiimide (DCC) by recycling wastewater

Abstract

The invention discloses a production method for preparing N,N'-dicyclohexylcarbodiimide (DCC) by recycling wastewater, belonging to the technical field of organic compound synthesis. The method solves the problem of unmanageable brine sewage at present. The method comprises the following steps: washing N,N'-dicyclohexylurea (DCU) generated after using DCC with water to remove impurities, reacting with an oxidizer in an organic solvent, dropwisely adding the reaction solution into an alkali water solution to carry out neutralization reaction, filtering the neutralization reaction product, standing to stratify, and carrying out distillation separation on the organic layer to obtain the DCC product, wherein the distilled solvent is directly recovered; and filtering out inorganic salts from the water layer to obtain recovered water for preparing the alkali solution. The DCU generated after using the DCC is recovered to obtain the DCC; and the generated brine wastewater is recycled, thereby reducing the discharge of the brine sewage and greatly lowering the brine sewage treatment.

Description

technical field

[0001] The invention relates to a production method of N,N'-dicyclohexylcarbodiimide, in particular to an environmentally friendly production method for the regeneration of N,N'-dicyclohexylcarbodiimide, which belongs to the synthesis of organic compounds technology field. Background technique

[0002] N,N'-Dicyclohexylcarbodiimide (DCC for short) is a shrinking agent commonly used in organic synthesis and pharmaceutical manufacturing industries. It can dehydrate two molecules that cannot react originally to form a chemical bond. In my country, it is mainly used for the synthesis of products such as amikacin and glutathione.

[0003] The structural formula of N,N'-dicyclohexylcarbodiimide is:

[0004]

[0005] DCC is used as a shrinking agent, and its reaction product is N,N'-dicyclohexyl urea (DCU). DCU is toxic and its discharge will pollute the environment. Utilizing the regeneration of DCU to prepare DCC can realize the regeneration and utilization...

Examples

Embodiment 1

[0039] Put 5kg of N,N'-dicyclohexyl urea raw material into 10kg of water, stir and soak for 40min, centrifuge the soaked DCU for dehydration, and then dry it in an oven at 110--120℃ until the water content is lower than 0.5%.

[0040] 175 g of chloroform was added into the three-necked flask, and 40.0 g of dried DCU was added under stirring. Weigh 30g of phosphorus oxychloride and add it to a 250mL dropping funnel. Phosphorus oxychloride was added dropwise to the three-necked flask under stirring, and the addition was completed within 30 minutes. After the addition was complete, the reaction was maintained at 55-60°C for 2 hours. Pour the reaction solution into the dropping funnel.

[0041] Add 400 g of waste water to the three-necked flask, add 45 g of solid sodium hydroxide under stirring, and stir for 20 minutes until all the sodium hydroxide is dissolved. Then the reaction solution was added dropwise to the three-neck flask, and the addition was completed in 60 minutes....

Embodiment 2

[0045] Referring to Example 1, the difference is that dichloromethane is used instead of chloroform. The reaction temperature after the dropwise addition of phosphorus oxychloride is 40-42°C; the neutralization reaction temperature is controlled below 40°C. The yield of DCC was 81.5%, and the purity was 99.4%.

[0046] It can be seen that in the present invention, the waste water containing inorganic salt produced by the reaction is separated from the system by filtration and then reused as a raw material, which reduces the discharge of waste water and the impact on the environment. At the same time, the use of the waste water containing saturated phosphate and sodium chloride of the present invention has no obvious influence on the product yield and purity of the DCC process prepared by DCU.

technical field

[0001] The invention relates to a production method of N,N'-dicyclohexylcarbodiimide, in particular to an environmentally friendly production method for the regeneration of N,N'-dicyclohexylcarbodiimide, which belongs to the synthesis of organic compounds technology field. Background technique

[0002] N,N'-Dicyclohexylcarbodiimide (DCC for short) is a shrinking agent commonly used in organic synthesis and pharmaceutical manufacturing industries. It can dehydrate two molecules that cannot react originally to form a chemical bond. In my country, it is mainly used for the synthesis of products such as amikacin and glutathione.

[0003] The structural formula of N,N'-dicyclohexylcarbodiimide is:

[0004]

[0005] DCC is used as a shrinking agent, and its reaction product is N,N'-dicyclohexyl urea (DCU). DCU is toxic and its discharge will pollute the environment. Utilizing the regeneration of DCU to prepare DCC can realize the regeneration and utilization...

Examples

Embodiment 1

[0039] Put 5kg of N,N'-dicyclohexyl urea raw material into 10kg of water, stir and soak for 40min, centrifuge the soaked DCU for dehydration, and then dry it in an oven at 110--120℃ until the water content is lower than 0.5%.

[0040] 175 g of chloroform was added into the three-necked flask, and 40.0 g of dried DCU was added under stirring. Weigh 30g of phosphorus oxychloride and add it to a 250mL dropping funnel. Phosphorus oxychloride was added dropwise to the three-necked flask under stirring, and the addition was completed within 30 minutes. After the addition was complete, the reaction was maintained at 55-60°C for 2 hours. Pour the reaction solution into the dropping funnel.

[0041] Add 400 g of waste water to the three-necked flask, add 45 g of solid sodium hydroxide under stirring, and stir for 20 minutes until all the sodium hydroxide is dissolved. Then the reaction solution was added dropwise to the three-neck flask, and the addition was completed in 60 minutes....

Embodiment 2

[0045] Referring to Example 1, the difference is that dichloromethane is used instead of chloroform. The reaction temperature after the dropwise addition of phosphorus oxychloride is 40-42°C; the neutralization reaction temperature is controlled below 40°C. The yield of DCC was 81.5%, and the purity was 99.4%.

[0046] It can be seen that in the present invention, the waste water containing inorganic salt produced by the reaction is separated from the system by filtration and then reused as a raw material, which reduces the discharge of waste water and the impact on the environment. At the same time, the use of the waste water containing saturated phosphate and sodium chloride of the present invention has no obvious influence on the product yield and purity of the DCC process prepared by DCU.

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