Has anyone actually performed a rigourous analysis of the product obtained by this reaction to determine it's unequivocal composition?
According to JCS 1953, p. 3255 the only recoverable compound is 1,2-diphenylethanolamine.
| Quote: | EXPERIMENTAL
All the decarboxylations were carried out under similar conditions, which are described for the typical case of +/- alanine.
Decarboxylation of DL-Alanine in Benzaldehyde.-DL-Alanine (10 g., 0.11 mole) and freshly distilled benzaldehyde (100 c.c., 1 mole) were heated in a
200-C.C. Claisen flask (thermometer in liquid), fitted so that gases evolved were passed through a trap cooled by solid carbon dioxide and alcohol
into a test-tube containing lime-water. At about 120” the alanine dissolved with effervescence, and heating was continued so as to distil off water
formed but as far as possible retain the benzaldehyde (2-5” below the b. p.). After 5-10 min. evolution of carbon dioxide practically ceased; in the
trap were found ice, acetaldehyde, and a little benzaldehyde. The cooled deep red reaction mixture was shaken with 6N-hydrochlonc acid
(200 c.c.) and distilled in steam to remove all the benzaldehyde. The hot acid solution was boiled with 2 g. of animal charcoal, then filtered, and
the boiling filtrate was cautiously made alkaline with pellets of sodium hydroxide. This treatment was necessary in order to ensure the precipitation
of the bases in a crystalline and filtrable form. After several hours the solid was collected, washed with water, and dried to give 2 g. of crude
product (8.4%). The two racemic forms of 8-hydroxy-1 : 2-diphenylethylamine were separated from the crude product by shaking with ether (150 c.c.), in
which the is0 is much more soluble than the normal isomer. The residue, recrystallised from benzene, had m. p. 163-164” (Found : C, ‘78.8; H, 6-8;
N, 6-7. Calc. for C,,H,,ON : C, 78.8; H, 7.0; N, 6-6%), unaltered by admixture with an authentic specimen of normal 2-hydroxy-1 : 2 diphenylethylamine
(Weijlard, Pfister, Swanezy, Robinson, and Tishler, J. Amer. Chem. SOL, 1951, 73, 1216). The N-acetyl derivative (from ethanol) had m. p. 196’ ;
Soderbaum (Bey., 1896, 29, 1210) gives m. p. 196-197O. |
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I was in a hurry and should have thought
more about my post.
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