SU413146A1 - - Google Patents

Description

one

This invention relates to the field of acetylene-based monomer synthesis.

A method of producing N-vinylcaprolactam by reacting caprolactam with acetylene B of a gas-liquid emulsion at a temperature of 130-190 ° C in the presence of lactam as the catalyst and isolating the desired product by known methods is used (yield is 67.2%).

However, this method is characterized by low activity of the prepared catalytic solution, because in an alkaline medium and at elevated temperatures the lactam cycle is eroded and a large part of KOH is formed to form the potassium salt of aminocaproic acid (by-product), which reduces the activity of the catalyst. In connection with this, the yield of N-vinylcaprolactam and its quality are rather low.

In order to increase the yield of the target product and improve its quality, the potassium salt of lactam is used, obtained by gradual separation of an alcoholic solution of KOH into the initial cairolactam while simultaneously distilling alcohol and water formed.

The proposed method allows to obtain good quality N-vinylcaprolactam in 80% yield.

Example. To 520 g of molten caprolactam, a solution of 7.15 g is gradually added.

KOH in alcohol. The alcohol and the water formed is continuously distilled off under vacuum at a residual pressure of 2-10 mm Hg. Art. The resulting solution of 25 g of catalyst in 500 g of caprolactam is loaded into a 1 liter reactor equipped with a jacket and a good stirrer, heated to 150 ° C, acetylene is fed, maintaining a constant pressure of 0.4-0.5 ati, turning on the stirrer and conducting vinyl

160-170 ° C for 1.5-2 hours.

In the course of the process, the reaction mass is analyzed. At the end of the process, the reaction mass is subjected to a single distillation, the separation of resinous products, together with the catalyst. Distillate is subjected to distillation under vacuum, with a residual pressure of 2-5 mm RT. Art. The efficiency of the column is 10 tons, with full irrigation, the reflux number 5-8, the temperature taken

pure vinylcaprolactam 86-88 ° C with a residual pressure of 1.5-2 mm RT. Art.

As a result of the process, receive;

vinyl caprolactam with a purity higher than 98 wt.%, g348

caprolactam returned for

re-vinylation, g 158 amount of resinous products, g67

the yield of vinylcaprolactam taking into account the return of caprolactam,% 80

Subject invention

The method of obtaining N-vinylcaprolactam by the interaction of caprolactam with acetylene in a gas-liquid emulsion with increased

temperature in the presence of a potassium salt of lactam as a catalyst and extraction of the target product by known methods, characterized in that the potassium salt of lactam obtained by gradual separation of an alcoholic solution of KOH into the initial caprolactam while simultaneously distilling alcohol and water formed is used to increase the yield of the target product .