Methyl «-bromo-/3-methoxypropioNATE

C) dl-Serine.—One-half (350-375 g.) of the crude bromo-methoxypropionic acid prepared from the saponification of 800 g. of methyl a-bromo-/3-methoxypropionate is heated with 3.5 1. of concentrated ammonium hydroxide in a glass-lined autoclave (Note T4) for ten to fifteen hours at 90-100°, and the solution from the bomb is concentrated to a thick syrup under reduced pressure (Note 15). Two liters of water is added, and the solution is concentrated to dryness. The cake is dissolved in 1.5 1. of 48 per cent hydrobromic acid and refluxed for two and one-half hours. The resulting dark solution is concentrated to a volume of about 500 cc. and then cooled under the tap. The... 

The crude ester may be used directly in the preparation of serine. However, greater ease of purification and slightly better yields make it advantageous to prepare the free acid. Pure methyl a-bromo-j8-methoxypropionate is obtained by fractionally distilling the crude material under reduced pressure through a Widmer column. From 100 g. of crude material there is obtained 80-90 g. of pure ester, b.p. 73-75°/6 mm., n 1.4586. 

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