Org. Synth. 1923, 3, 51
DOI: 10.15227/orgsyn.003.0051
[Propionic acid, β-bromo-, ethyl ester]
Submitted by E. C. Kendall and B. McKenzie.
Checked by H. T. Clarke and M. R. Brethen.
1. Procedure
To the crude mixture of ammonium bromide and β-bromopropionic acid, prepared as described on p. 131, from 317 g. of ethylene cyanohydrin, are added 1200 cc. of carbon tetrachloride (Note 1) and 200 cc. of the same solvent which has been shaken with the aqueous distillates; the ammonium bromide is filtered off and washed with 200 cc. of carbon tetrachloride. The watery layer, amounting to about 350 cc., is separated and shaken with 100 cc. of carbon tetrachloride. To the united carbon tetrachloride solutions are added 450 cc. of 95 per cent ethyl alcohol and 10 g. of sulfosalicylic acid or phenolsulfonic acid to act as a catalyst (Note 2).
The mixture is now boiled in a 3-l. flask, the vapors being passed through an efficient condenser and the condensed liquid run into an automatic separator (p. 422) so arranged that the heavy liquid is returned to the flask and the lighter aqueous liquid discarded. If the boiling is sufficiently vigorous no more water will separate after two to two and one-half hours' boiling (Note 3). The reaction mixture is now cooled, washed with dilute sodium carbonate solution, and distilled with the use of a column until the temperature of the vapor reaches 85° and that of the liquid in the flask about 115°. The residue is then transferred to a flask provided with a column for distillation under reduced pressure (Fig. 9, p. 130) and distilled. The fraction boiling at 60–65°/15 mm. is collected, 690–700 g. of pure ethyl β-bromopropionate being obtained (85–87 per cent of the theoretical amount). A high-boiling residue, probably consisting of ethyl hydracrylate, remains in the flask, but the amount is practically negligible.
2. Notes
1. As in the preparation of the β-bromopropionic acid (p. 131), benzene must not be substituted for the carbon tetrachloride, as it has been found impossible to make a satisfactory separation of this solvent from the ester.
2. The esterification may be carried out without the addition of a sulfonic acid, as traces of hydrobromic acid generally remain in the crude material; but since the time of operation must be kept as short as possible this omission is not recommended. It has been found that, if the water is not removed and the mixture boiled under a reflux condenser for two hours before the distillate is passed through the automatic separator, the yield falls to 70–75 per cent of the theoretical amount.
3. It is important to carry out the esterification as rapidly as possible in order to cut down to a minimum the formation of ethyl hydracrylate, which takes place by the action of water on the β-bromopropionic acid or ester; an efficient condenser is therefore necessary. For the same reason it is necessary to remove all residual water from the mixture before adding the alcohol.
3. Discussion
Ethyl β-bromopropionate can be prepared by the esterification of β-bromopropionic acid,1 and by the addition of hydrogen bromide to ethyl acrylate.2
This preparation is referenced from:

References and Notes
  1. Lederer, J. prakt. Chem. (2) 42, 384 (1890); Barthe, Compt. rend. 118, 1268 (1894).
  2. Org. Syn. 20, 64.

Chemical Abstracts Nomenclature (Collective Index Number);
(Registry Number)


sulfonic acid

ethyl alcohol,
alcohol (64-17-5)

Benzene (71-43-2)

ammonium bromide (12124-97-9)

hydrogen bromide (10035-10-6)

sodium carbonate (497-19-8)

carbon tetrachloride (56-23-5)

β-Bromopropionic acid (590-92-1)

Ethylene cyanohydrin (109-78-4)

Ethyl β-bromopropionate,
Propionic acid, β-bromo-, ethyl ester (539-74-2)

sulfosalicylic acid

phenolsulfonic acid

ethyl hydracrylate (623-72-3)

ethyl acrylate (140-88-5)