It was found that the preparation process of n-vinylcaprolactam is carried out by distilling and reacting a lactam with an aqueous alkali metal hydroxide solution and then reacting with acetylene, that is, an alkali metal hydroxide from a lactam and a specific gravity of 0.1 to 0.9. The aqueous solution is concentrated and concentrated at a temperature of 50-250 degrees Celsius for a residence time of 0.1-0.5 h, and then reacted with acetylene at 60-250 degrees Celsius and 0.1-10 kPa.
In the case of a strong alkali metal as a catalyst, the reaction of lactam, amide and acetylene can avoid the formation of trace amounts of water in batch formation by using soda ash metal. Since it is difficult to control the reaction conditions of alkali metals, this method is in n- Vinyl caprolactam is not suitable in the industrial field.
Using an alkali metal salt of an alcohol having a space-shielding structure, the resulting alcohol having a space-shielding structure is easily removed, and it does not cause ring opening of the lactam. However, this process also has the disadvantage that strong basic compounds are formed. Zibo n-vinylcaprolactam introduces these catalysts to be particularly expensive, and the resulting alcohol is still present in the distillate of the lactam, so it must be separated and removed.
The NVCL manufacturer found that a patent indicates the preparation of an alkali metal salt of pyrrolidone for the preparation of a polymer. The alkali metal salt solution and pyrrolidone are reacted at a low pressure of 170-250 degrees Celsius, and the solution includes alcohol, ether and hydrocarbon. Compounds, etc.