09-23-03 23:04
No 460615
In the Ref they go on and make the methyl ester with MeN2, which could be used as in Post 333615 (Barium: "Holy cow!!!", Novel Discourse). If anybee's interested, ask.
alpha-bromopropionic acid
Alanine (4.0g, 45 mmol) was added to a saturated solution of KBr (10ml), followed by dropwise addition of HBr (15ml of a 47% soln). The resulting mixture was then cooled to 0°C and NaNO2 (6.21g, 90mmol) was added over 1h. The reaction mixture was maintained below 5°C for a further 1h and then allowed to warm to room temp. The resulting soln was then extracted Et2O (3 x 25ml), the combined ether extracts were then dried over MgSO4 and concentrated in vacuo to give a pale yellow oil (6.54g) in 95% yield. This was distilled under reduced pressure to give pure bromopropanoic acid. B.p. 68-70°C/0.1 mmHg.
Ref: Archer, Catherine H.; Thomas, Neil R.; Gani, David; TASYE3; Tetrahedron: Asymmetry; EN; 4; 6; 1993; 1141-1152
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(Chief Bee)
09-24-03 03:29
No 460648
That is a great procedure you have resurrected, but it has already been posted in Post 264850 (ChemicalSolution: "space efficient, easy 2-Br-propionic acid prep", Methods Discourse)
For those interested in the preparation of alpha-halogenated propionic acids from alanine, there are 20 references to similar procedures listed in Post 221276 (megamole: "Re: Easy nitroethane in quantitative yield", Methods Discourse)
Also see the following posts:
Post 221895 (lugh: "(R)-2-Bromopropionic Acid from D-Alanine", Methods Discourse)
Post 346512 (moo: "alpha-bromopropionic acid from lactic acid", Methods Discourse)
Post 220587 (foxy2: "Preparation of alpha-Bromo Carboxylic Acids", Methods Discourse)