THE CHEMICAL CONSTITUTION OF THE UNITS 101 



,OH X)H 



C 6 H 4 < ,NH.COC 6 H 6 -> C 6 H 4 / .NHCOCeH, 



\CH=CC \CH 2 .CH< 



\COOH \COOH 



X OH 

 -> C 6 H/ 



\CH 2 .CH(NH 2 )COOH 



Just as in the case of phenylalanine, p-oxy-a-benzoylaminocinnamic 

 acid, when treated with ammonia, yields a substance which reacts 

 with ammonia giving a complex compound ; this, on hydrolysis, 

 by heating in a sealed tube with hydrochloric acid, is converted into 

 tyrosine. 



Tyrosine is most conveniently prepared by synthesis from anisalde- 

 hyde and hydantoin. (Compare preparation of phenylalanine p. 97). 

 Wheeler and Hoffmann have obtained an excellent yield in two opera- 

 tions : 



HN CO HN CO 



OC OC 



HN CH 2 + OCH . C 6 H 4 . OCH 3 = HN C = CH . C 6 H 4 . OCH 3 + H 2 O 

 HN CO 



OC + 5HI + 2H 2 O = COOH 



HN C = CH . C 6 H 4 . OCH 3 HI . H 2 N CH CH 2 . C 6 H 4 OH + 



NH 4 I + CH 3 I + CO a + I 2 . 



Tyrosine is obtained from the hydriodide by treatment with am- 

 monia. 



