Chemie pro všechny - CHEMIE-PRO-VSECHNY.PHP5.CZ | ANGLICTINA.ASPONE.CZ | MATEMATIKA.ASPONE.CZ     Original czech version here
Main menu


Sponsored links

Preparation malonate

In the 5-liter round bottom flask is placed 500 g (5.3 mol) of chloroacetic acid and 700 ml of water. Heat the solution to 50 ° C, neutralize 290 g (2.7 mol) of anhydrous sodium carbonate and cooled to room temperature. Meanwhile, dissolve 294 g (6 mol) of sodium cyanide in 750 ml of water and cooled to room temperature. Then a solution of sodium cyanide begin cautiously added to a solution chloroctanu solution (reaction mixture and stir chladíme water). After adding all chloroctanu sodium cooling pause and let the temperature rise. After reaching 95 ° C, chladíme solution by adding 200 ml of ice water so that the temperature is not rising further. After cessation of the exothermic reaction (temperature no longer grow) heat the flask for 1 hour on a steam bath to complete the reaction. After heating the solution is cooled to room temperature and the reaction mixture slowly add 240 g (6 mol) of sodium hydroxide. When hydroxide dissolved, the reaction mixture was heated on a steam bath. Once the temperature reaches 60-70 ° C, begins to evolve ammonia (The dissociation nitrile group) and the temperature is rising rapidly. Most ammonia evolves during 45 minutes and heat the solution for 3 hours. The last remnants remove ammonia solution bubbling hot steam (about 60 minutes). The hot reaction mixture are added slowly with stirring a solution of 600 g of anhydrous calcium chloride (of course it is possible to use hexahydrate) in 1.8 liters of water heated to 40 ° C. Then let the mixture rest for. After 24 hours the precipitated calcium malonate five decanted 500 ml of ice water. Sucked on a Buchner funnel and dried in air at 40-50 ° C to constant weight. Yield: 800-900 g

Kyselina malonová - reakční schéma, rovnice

   Dry calcium malonate placed into a 3 liter round bottom flask and adding 750-1000 ml of ethanol to a pasty consistency which can be stirred with the stirrer. The flask is placed into a cooling bath (ice + NaCl) and stirring begin dropping funnel added conc. hydrochloric acid (1 ml per 1 g of anhydrous calcium malonate). After addition of hydrochloric acid the resulting mixture was extracted with ether (ideally extractor see Figure 1). The ether layer separated and without drying thicken distilling off the ether. Cooling the drop from the reaction mixture, crystals of malonic acid, which dry the air. Yield: 415-440 g Melting point 130 ° C and above.

Extrakce kyseliny malonové etherem

Sponsored links