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

blondie
(Stranger)
01-26-02 09:02
No 261050
      phenylalanine --> benzyl cyanide

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

summary
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.

C6H5CH2R
XI    R = CN
XII R = CHO
XIII R = COOH

source: Biochimica et Biophysics Ada, 313 (1973) 170-180

terbium
(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.

Elementary
(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

Elementary
(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.

http://www.chemistry.mcmaster.ca/courses/2oa3/labmanual/expt6/2oa3exp6.html
John Lennon - Working Class Hero

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


		blondie (Stranger) 01-26-02 09:02 No 261050				phenylalanine --> benzyl cyanide
						The reaction of aqueous hypochlorous acid with a-amino acids and dipeptides summary 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. C6H5CH2R XI R = CN XII R = CHO XIII R = COOH source: Biochimica et Biophysics Ada, 313 (1973) 170-180



		terbium (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.



		Elementary (Hive Addict) 05-29-02 08:04 No 315550				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



		Elementary (Hive Addict) 05-29-02 09:38 No 315567				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. http://www.chemistry.mcmaster.ca/courses/2oa3/labmanual/expt6/2oa3exp6.html John Lennon - Working Class Hero

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