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Working Bee
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Joined: 13 Feb 2005 |
Posts: 236 |
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9718.84 Points
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re: n-methylalanine synthesis
Fri May 13, 2005 6:36 am |
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If anyone has thought perhaps methylation w/ HCHO was possible sorry to disapoint you. There is a not so hidden gem in here however!
Following was taken from this fine article posted by Java recently. Java has to be the smartest chemist ever having read and absorbed all these articles.
The Action of Formaldehyde on Amines and Amino Acids; By H. T. Clarke, H. B. Gillespie & S. Z. Weisshaus; JACS 55, 4571-4587, Nov. 1933.
The behaviour of aliphatic amino acids toward formaldehyde similarly displays the effect of the unsaturation inherent in the carboxyl group. Zeleny and Gortner
[17]Zeleny and Gortner. J. Biol. Chem., 90, 427 (1931). have recently shown that when alanine, glutamic acid, tyrosine and cystine are boiled with an excess of formaldehyde in 20% hydrochloric acid, as much as 40% of the nitrogen is eliminated as methylamine. We find analogous decompositions to
take place on warming amino acids with formaldehyde in formic and acetic acids. Glycine under these conditions yields 60-70% of dimethylglycine, but at the same time considerable amounts of more complex, non-crystallizable products, as well as 6% of volatile base (mostly trimethylamine) are formed in the reaction. b-Aminopropionic acid behaves in much the same way, though the yield of the dimethyl derivative is distinctly lower. With alanine, on the other hand, none of the dimethyl derivative could be secured; a complex mixture was formed, and 36% of the nitrogen was converted into methylamines. Similar results were obtained with
leucine, a-aminocaprylic acid and glutamic acid, in all of which an even greater proportion of the nitrogen was split oh. When the formic acid was replaced by acetic acid, volatile bases were produced, but definitely less carbon dioxide was liberated.
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Drats, sounded like a good idea at first sans HCl. What about trying methylation w/ HCHO on the ester? |
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