Preparation of 5,5-diphenylhygantion - Synthesis of Dilantin - Lu Le Laboratory

The sodium salt of 5,5-diphenylhygantion, Dilantin, is an anticonvulsant used for the treatment of epilepsy. 

(See also: Preparation of Benzil - Synthesis of Dilantin

                   Preparation of Benzoin - Synthesis of Dilantin )

The synthesis process of 5,5-diphenylhygantion is as follows:

Reaction equation:

Mechanism:

Chemical

1.      Benzil: 0.60 g

2.      Urea: 0.36 g

 

3.      Potassium hydroxide solution: ~2mL saturated(~14.8M)

4.      Sulfuric acid: 6M

5.      Ethanol 95%

Procedure

1.      Add 0.60g benzil and 0.36g urea in to a 50mL round-bottomed flask

2.      Add 6 mL 95% ethanol and 1~2mL KOH solution.

3.      Reflux the mixture with stirring for 2.5 hr.

4.      Cool the reaction mixture and remove the sparingly insoluble solid by gravity filtration.

5.      Cool the filtrate further in an ice-water bath and acidify the filtrate with 6M sulfuric (pH 1.5~3). The white powdered solid is obtained.

6.      Collect the product by filtration, and wash it thoroughly with water to remove the inorganic salt.

7.      Recrystallize the crude product from 95% ethanol.

8.      The white needle-shape crystal is obtained.

 

Experimental Record

Weight of benzil	0.60 g
Weight of final product (Dilantin)	0.36 g
Theoretical Weight of Dilantin	0.72 g
Yield	50.0 %