[영문]펜토바르비탈 제조법

출처 : rhodium

Pentobarbitone. (Called Nembutal or Pentobarbital.) 26.7 g of clean metallic sodium are dissolved in 400 g of anhydrous (dry) ethanol. To this, a solution of 100 g of 1-methyl butyl-ethyl malonic ester and 37.2 g of dry urea is added. The mixture is heated for 4 to 6 hours in an autoclave, or refluxed for 20 to 40 hours. The alcohol is then removed by distillation. The residue is dissolved in water and this aqueous solution is acidified with hydrochloric acid. The precipitated product is filtered, washed with cold water, and recrystallized from boiling water. Yield: depends on your ability to exclude H2O from the beginning of the reaction, mp: 127-130℃.

Synthesis of Malonic Acid

100 g of powdered chloroacetic acid is treated with 150 g of broken ice and dissolved in 125 g of caustic soda (33 1/4%) solution. The solution should be made exactly neutral, if it is not already (this refers to the mixture). After neutralizing, add 69 g of 98% potassium cyanide in 130 g of water, which has been warmed to 40℃. An hour after the addition, the mixture is slowly warmed to 100℃ and held at this temp for an hour. Cool slowly to 25℃ and add another 125 g of 33 1/4% caustic soda solution. Slowly heat the mixture to 100℃ and hold at that temp until no more ammonia is evolved (2 to 3 hours). To test: add sodium hydroxide solution to a sample and boil. If no ammonia evolves, then the reaction is complete. When the reaction is complete, the solution is cooled, acidified with dilute HCl acid, and carefully evaporated to complete dryness on a water bath. The residue is powdered, extracted repeatedly with ether, and the ether is removed by gently heating on a water bath. You may purify further by dissolving in the minimum amount of caustic soda solution, boiling with decolorizing carbon, acidifying and extracting with ether, as before. Yield: 95 g, mp: 132℃.

Synthesis of Urea

50 g of potassium cyanide is heated in an iron crucible under a large flame until it begins to fuse. 140 g of red lead is added in small portions, while the mixture is stirred with a rod. When the addition is complete and the frothing has stopped, the fused mass is poured onto an iron tray. When cold, the mass is separated from metallic lead, ground up, and digested with 200 cc of cold water for 1 hour. The filtrate from this mixture is treated with 25 g of ammonium sulphate and evaporated to dryness on a water bath. The residue is powdered well, transferred to a flask and is boiled with 3 installments of ethanol under reflux, to dissolve the urea from the potassium sulphate. Each of the 3 ethanol extracts is filtered, then combined, and evaporated to a small bulk, until crystals of urea separate on cooling and standing. Mp: 132℃.