CH. IV.] ASPARTIC ACID. 81 



Aspartic Acid. 



82. Preparation from Asparagine. Asparagine is the amide of 

 aspartic acid, and it is converted to the acid by hydrolysis with acids. 



HC1 



CH(NH 2 ).COOH.H 2 CH(NH 2 ).COOH 



+ 2HC1 = | + NH 4 C1. 



CH 2 .CONH 2 CH 2 .COOH 



Crystalline asparagine Aspartic acid hydrochloride 



Mol.Wt. = 150. 



The hydrochloride is converted to aspartic acid by the addition of 

 the calculated amount of sodium hydroxide. 



(i.) Into a 500 cc. round-bottomed flask introduce 15 grams, of 

 crystalline asparagine (i/io gm. mol.) and 200 cc. of 

 N.HC1 (2/10 gm. mol.). 



(ii.) Boil gently on a sand bath under an efficient reflux con- 

 denser for 6 hours. 



(iii.) Cool and add 100 cc. of N.NaOH (i/io gm. mol.), shaking 

 during the addition. Set aside to crystallise in a cool 

 place. (This soda is to convert aspartic acid hydro- 

 chloride into free aspartic acid.) 



(iv.) Stir well and filter on a Buchner, and wash with small 

 amounts of cold water. Reserve the filtrate and wash- 

 ings for obtaining copper aspartate, or a further crop of 

 crystals by evaporation. 



(v.) Recrystallise by dissolving in the smallest possible amount 

 of 50 per cent alcohol, filtering through a hot water 

 funnel, and allowing to stand till quite cold. 



(vi.) Filter on a Buchner and dry in the air. Add the filtrate to 

 that obtained in (iv.). 



Yield: about 12 grams, of the recrystallised product. 



