The preparation process of n-vinyl caprolactam is carried out by distilling and reacting a lactam with an aqueous alkali metal hydroxide solution and then reacting with acetylene, that is, an aqueous solution of an alkali metal hydroxide from a lactam to a specific gravity of 0.1 to 0.9 at 50 - At a temperature of 250 ° C, the residence time is 0.1-0.5 h, which is concentrated by distillation, and then reacted with acetylene at 60-250 ° C and 0.1-10 kPa to form.
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.