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All 4 posts   Subject: phenylalanine --> benzyl cyanide   Please login to post   Down

01-26-02 09:02
No 261050
      phenylalanine --> benzyl cyanide     

The  reaction  of  aqueous  hypochlorous  acid  with  a-amino acids  and  dipeptides

HOC1  by  oxidative  decarboxylation  converts  several  a-amino  acids  into  a  mixture  of  the  corresponding nitriles  (major)  and  aldehydes  (minor  product).  In addition,  chlorination  of the  ring  of tyrosine  was observed.  Cysteine  when  reacted  with HOC1  yielded cystine  and  cysteic  acid,  while  with  cystine,  cysteic  acid  was  the  only product  identified.  The  amide  nitrogen  bond  of  several  dipeptides 

The  reaction  of  a-amino  acids  (I)  with  NaOCl  was  investigated  by  Langheld' who  observed  the  production  of  an  aldehyde  (II),  CO  and  NH,.  Subsequently, Dakinssg  demonstrated  that  one  equivalent  of  the  N-chloro  compound,  chloramine T  [(N-chloro-p-toluenesulfonamido) sodium]  converted  a-amino  acids  to  their corresponding  aldehydes  (II)  while  if  two  equivalents  of reagent  were  used"  the corresponding  nitriles  (III)  resulted. 

Wright found  that  aldehydes  were formed  from several  a-amino  acids  by  reaction  with  NaOCl  while  nitriles  predominated  at  lower pH  values. 
(11  Wright,  N.  C. (1936)  Biochem.  J.  30, 1661-1667)

Reaction  of  L-phenylalanine  with  HOC!  Two  products  were  obtained  from  the  reaction  of  HOC1 with  l-phenylalanine. They  were  identified  by gas chromatography-mass  spectrometry  as  phenylacetonitrile (XI,  95 % of  the  reaction  mixture)  and phenylacetaldehyde  (XII,  5 T/,). Acid  hydrolysis  of  the  crude  reaction  mixture  yielded phenylacetic  acid  (XIII)  which  was  identified  from  its  m.p.,  mixed  m.p.  with  an  authentic  sample  and  mass  spectrum.

XI     R = CN

source: Biochimica  et  Biophysics  Ada,  313 (1973)  170-180
(Old P2P Cook)
01-26-02 15:32
No 261115
      Re: phenylalanine --> benzyl cyanide     

Good information, from time to time people around here have wondered about what one would get from a hypohalite oxidation of phenylalanine.
(Hive Addict)
05-29-02 08:04
No 315550
User Picture 
      pH ?     

Would the pH of hypochlorous acid be low enough on its own to convert the L-phenylalanine to phenylacetonitrile ?

John Lennon - Working Class Hero
(Hive Addict)
05-29-02 09:38
No 315567
User Picture 
      Looking at this oxidation with hypochlorous acid, ...     

Looking at this oxidation with hypochlorous acid, it looks as though acetic acid (or maybe another organic acid) can be used to release the hypochlorous acid from common household bleach. Adding extra acetic acid would maybe lower the pH far enough to allow benzyl cyanide to be formed in good yield.

John Lennon - Working Class Hero

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