In repeating the work which has been described by Hahn, Kelley and Schaeff er,l results have been obtained which necessitate a complete revision of the conclusions then published. It now seems certain that the ethyl a-bromopropionate2 which was then used in condensation with the sodium derivative of anisalhydantoin contained appreciable quantities of the corresponding acetic ester. Recently a different specimen of ethyl a-brom~propionate~ was used with the result that an entirely new propionate derivative, m. p. 158-158.5', was obtained which in turn yielded a quite different series of compounds from those which had previously been described. The new substance4 has now been identified as ethyl anisalhydantoin-N-1-propionate.This substance was at first assumed to be a position isomer of the esters melting a t 176' and 143' that were obtained in all previous condensations, and it was with a view to establishing these relationships that all three esters were submitted to Dr. Emma P. Carr, of this Laboratory, for spectrographic examination. When results showed that the absorption curves of all three substances were practically identical, it seemed probable that their several relationships could no longer be accounted for on the basis of N-1 and N-3 substitution in the hydantoin ring. Since, however, such deductions depend for accuracy upon the comparison of the absorption curves of a large number of substances of definitely known structure, the development of this phase of the problem necessitated the preparation of additional derivatives of anisalhydantoin. Dr. Carr will Hahn, Kelley and Schaeffer, THIS JOURNAL, 45, 843 (1923).This ester boiled a t 158-160" but was prepared from a very impure propionic acid that was obtained from the General Chemical Company in 1918. This acid was rectified and a fraction boiling a t 138-142" was used in the preparation of ethyl abromopropionate.This ester also boiled at 158-160° but was prepared from a propionic acid boiling at 139-141°, obtained from C. A. F. Kahlbaum. In both cases the Zelinsky method [Be?., 20,2026 (1887) J was used in the preparation of the halogen ester. Acknowledgment is made to Miss Woodward for the preparation of pure ethyl a-bromopropionate.See Part I1 of this paper.
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