THE CHEMICAL CONSTITUTION OF THE UNITS 97 



COOH CH 2 . C 6 H 5 



y CH 2 . C 6 H 5 + C 6 H 4 (COOH) 2 + C0 2 



( + H 2 =CH.NH 2 



\NH . COC 6 H 4 COOH 

 COOH COOH 



Phthalimidobenzylmalonic Phenylalanine Phthalic acid 



acid 



Wheeler and Hofmann, in 1911, showed that phenylalanine is very 

 readily prepared from benzaldehyde and hydantoin. By the conden- 

 sation of these compounds in acetic acid solution in presence of sodium 

 acetate, benzalhydantoin is formed : 



HN CO HN CO 



OC OC 



HN CH 2 + OCH . C 6 H 5 = HN C = CH . C 6 H 5 + H 2 O 



By the action of hydriodic acid this compound is reduced to benzyl- 

 hydantoin, 



HN CO HN CO 



OC OC 



HN C = CH . C 6 H 5 + H 2 = HN CH CH a . C 6 H 5 



which, on saponification with baryta, is converted into phenylalanine, 

 carbon dioxide and ammonia : 



HN CO 



OC + 2 H 2 = COOH 



HN CH CH 2 . C 6 H 5 H 2 N CH CH a . C 6 H 5 + CO 2 + NH 3 



Benzalhydantoin is converted directly into phenylalanine hydriodide- 

 by boiling for several hours with hydriodic acid : 



HN CO 



\\ 



+ 4 HI + 2H 2 O = COOH 



HN C = CH . C 6 H 5 HI . H 2 N CH CH 2 . C 6 H 5 + NHJ + CO a + I, 



PT. I. 



