Preparation method of anhydrous DCC

Abstract

The invention belongs to the technical field of preparation of chemical intermediates, and particularly relates to a preparation method of anhydrous DCC, which comprises the following steps: adding a trace amount of anhydrous acid into a crude product toluene DCC mixed solution, stirring at 0-30 DEG C for 0.5-2 hours, then removing a toluene solvent, rectifying to obtain anhydrous DCC, promoting the reaction of trace amount of water in DCC toluene under the catalysis of acid, and removing the water in the crude product of toluene DCC; a chemical method is adopted, under the acid catalysis condition, the reaction of residual moisture in a DCC toluene solution is accelerated, DCU (N, N-dicyclohexylurea) is generated in advance, and anhydrous DCC is obtained in a solvent removal and rectification purification mode, so that the product quality is improved, and the new anhydrous DCC standard in the fields of pharmaceutical chemical engineering and electronic electroplating is met.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical intermediate preparation, and specifically relates to a method for preparing anhydrous DCC. Background Art

[0002] DCC (N,N-dicyclohexylcarbodiimide) is a widely used dehydrating agent in the fields of chemical industry and pharmaceutical industry. It is widely used in the synthesis of esters and amides. With the continuous improvement of customers' requirements for product quality and the application of new electronic industries, anhydrous DCC (≤10ppm) is required by downstream customers. Anhydrous DCC has a long shelf life and will not become turbid (high residual moisture content gradually generates N,N-dicyclohexylurea, causing turbidity) or unstable quality during the storage process. In addition, the electroplating industry has extremely high requirements for moisture. Therefore, the market share of anhydrous DCC is increasing year by year. Summary of the invention

[0003] The object of the present invention is to provide a method for preparing anhydrous DCC.

[0004] The technical solution adopted by the present invention to solve the technical problem is: a method for preparing anhydrous DCC, comprising the following steps:

[0005] 1) Add a trace amount of anhydrous acid to the crude toluene DCC mixed solution and stir at 0-30°C for 0.5-2h;

[0006] 2) removing the toluene solvent and obtaining anhydrous DCC after distillation;

[0007] 3) Promote the reaction of trace moisture in DCC toluene under acid catalysis to remove moisture from crude toluene DCC product.

[0008] Specifically, the trace amount of anhydrous acid is 0.1‰ to 1‰ of the weight of the DCC toluene solution.

[0009] Specifically, the trace anhydrous acid is sulfuric acid, acetic acid, or formic acid.

[0010] The present invention has the following beneficial effects: the present invention adopts a chemical method to accelerate the reaction of residual water in a DCC toluene solution under acid catalysis conditions, generates DCU (N, N-dicyclohexylurea) in advance, and then obtains anhydrous DCC by desolvation, distillation and purification, thereby improving product quality and meeting the new anhydrous DCC standard in the fields of pharmaceutical chemical industry and electronic electroplating. DETAILED DESCRIPTION

[0011] The present invention will now be described in further detail.

[0012] A method for preparing anhydrous DCC comprises adding a trace amount of anhydrous acid to a crude toluene-DCC mixed solution, stirring at 0-30°C for 0.5-2h, removing the toluene solvent, and then rectifying to obtain anhydrous DCC (water content ≤10pmm).

[0013] The reaction of trace water in DCC toluene is promoted by acid catalysis to remove water from crude toluene DCC, thereby preparing anhydrous DCC. The reaction mechanism is as follows:

[0014]

[0015] In the above steps, a trace amount of anhydrous acid is added, which is 0.1‰ to 1‰ of the weight of the DCC toluene solution, preferably 0.1‰; the trace anhydrous acid is sulfuric acid, acetic acid, formic acid, preferably anhydrous sulfuric acid; the reaction temperature is 0 to 30°C, preferably 25°C; the reaction stirring time is 0.5 to 2h, preferably 0.5h.

[0016] Comparative Example:

[0017] 750 g of crude toluene DCC mixed solution was placed in a 1000 L four-necked bottle, and the toluene solvent was removed under reduced pressure to obtain a crude product for distillation. The purity of the product after distillation was 99.51%, and the water content was 0.12%.

[0018] Example 1

[0019] In a 1000L four-necked bottle, add 750g of crude toluene DCC mixed solution, add a trace amount of anhydrous sulfuric acid (0.075g), control the temperature at 25°C, stir for 0.5h, then remove the toluene solvent under reduced pressure to obtain a crude product for distillation. The product purity after distillation is 99.72% and the water content is 8pmm.

[0020] Example 2

[0021] In a 1000L four-necked bottle, add 750g of crude toluene DCC mixed solution, add a trace amount of anhydrous formic acid 0.75g, control the temperature at 5°C, stir for 2h, then remove the toluene solvent under reduced pressure to obtain a crude product for distillation. After distillation, the product purity is 99.58% and the water content is 10pmm.

[0022] Example 3

[0023] In a 1000L four-necked bottle, add 750g of crude toluene DCC mixed solution, add a trace amount of anhydrous acetic acid 0.5g, control the temperature at 15°C, stir for 1.5h, then remove the toluene solvent under reduced pressure to obtain a crude product for distillation. After distillation, the product purity is 9968% and the water content is 9pmm.

[0024] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0025] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing anhydrous DCC, characterized in that: The following steps are involved: 1) Add a trace amount of anhydrous acid to the crude toluene DCC mixed solution and stir at 0-30°C for 0.5-2h; 2) removing the toluene solvent and obtaining anhydrous DCC after distillation; 3) Promote the reaction of trace moisture in DCC toluene under acid catalysis to remove moisture from crude toluene DCC product.

2. The method for preparing anhydrous DCC according to claim 1, characterized in that: The trace amount of anhydrous acid is 0.1‰ to 1‰ of the weight of the DCC toluene solution.

3. The method for preparing anhydrous DCC according to claim 2, characterized in that: The trace anhydrous acid is sulfuric acid, acetic acid, and formic acid.

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