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CHARLES R. HAUSER AND EARLJORDAN
a solvent has been studied. The preparation of 3- and 4-bromofluorenes from the resulting
[CONTRIBUTION FROM
THE
VOl. 57
fluorene mercury derivatives has been described. COLUMBUS, OHIO
RECEIVED SEPTEMBER 26, 1935
CHEMICAL LABORATORY OF DUKEUNIVERSITY ]
The Removal of Hydrogen and Acid Radicals from Organic Compounds by Means of Bases. 11. The Removal of Acetic Acid from Acetyl-aldoximes by Alkalies BY CHARLES R. HAUSERAND EARLJORDAN As part of a general program on the removal of the elements of acids from organic compounds by means of bases it was of interest to study the removal of acetic acid from geometrically isomeric acetyl-aldoximes, (I) and (11).
the removal of the proton, thereby hindering the release of the acetate ion and formation of nitrile. Although the reactions of acetyl aldoximes with alkalies have been studied extensively in connection with the determination of configurations of aldoximes there appears to have been relatively R-C-H 0 0 R-C-H !! /I I1 '! little quantitative work carried out under conN-O-C-CH3 H3C-C-0-N trolled conditions. In this investigation we have (11) anti (0) (1) s w (a) studied these reactions at definite temperatures I t is well known that in the presence of alkali and in most cases have isolated almost quantitaone of these isomers eliminates acetic acid more tive yields of products. The results are given in readily than the other. Indeed, this reaction is the following tables. The melting points of the used to distinguish a pair of geometrically isomeric crude products and those recorded in the literaaldoximes ; the isomer whose acetyl derivative ture are listed consecutively following the yields. more readily forms nitrile is designated the p-, In most cases the melting points of the crude whereas the other is designated the a-isomer. products were either practically the same as those Formerly, it was assumed that the unstable ( p - ) reported in the literature or were raised to these acetate had the syn configuration simply because values after one recrystallization. the hydrogen atom and acetate group are in Discussion closer proximity in (I) than in (11); this view I t is often stated or implied in the literature was based presumably on the assumption that the elements of acetic acid were removed simultane- that acetyl-a-, and acetyl-0-aldoximes react enously. At the present time, however, the un- tirely differently toward alkali, that the CY- give stable ( p - ) acetate is assigned the anti configura- only oxime, and the p- only nitrile. Recently, tion (11), whereas the more stable (a-) isomer is however, it has been shownS that with sodium assigned the syn (I). This view is based on a hydroxide certain acetyl-p-aldoximes give both good deal of experimental evidence' accumulated nitrile and oxime, the yields of these products during the past ten years. It is supported also being dependent on the temperature, and now it on theoretical grounds on the basis of the hypothe- has been found that a t the temperature of the sis that, in the formation of nitrile, a proton is re- boiling water-bath a t least certain acetyl-cymoved first by the action of alkali followed by aldoximes with alkali give some nitrile in addition the release of the acetate ion. According to to the corresponding oxime. Mills,2 after the removal of a proton, the moveIt can be seen from Table I that, in general, ment of the nitrogen nucleus to form the triple acetyl-0-benzaldoximes with 2 N sodium hydroxbond of the nitrile favors the release of the acetate ide gave higher yields of oxime than nitrile a t O", ion, only in the case of the isomer with configura- but greater yields of nitrile at 30". These results tion (11). It should be pointed out also that the confirm and extend those previously reported. proximity of the acetate group to the hydrogen In Table I1 are given the yields of products atom in (I) might offer some steric hindrance to obtained from the reactions of certain acetyl-a( I ! For review of evidence, see Freudenberg, Slereochemie, 7, 974benzaldoximes with 2 iV sodium hydroxide. I t 979 ( 1 9 3 3 ) ; Perkin and Kipping. "Organic Chemistry Part 111, can be seen that at 61-A4° the "nitro derivative 1934, pp. 661.663. "
(2) Mills, J . SOC.Chem. fnd.. 61, 756 (1932).
(3) Hnuser and Sullivan, THISJ O U R N A L 66, 4611 (193.3)
REMOVAL OF ACETIC ACID FROM ACETYL-ALDOXIMES BY ALKALIES
Dec., 1935
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TABLE I PERCENTAGE YIELDSOF PRODUCTS FROM ACETYL-p-BENZALDOXIMES AND 2 N SODIUM HYDROXIDE Temp., Yield,
Acetyl derivative
4-Nitro4-Nitro3.4-Methylenedioxy3,4-Methylenedioxy4-Methoxy-a 4-Methoxy-a 4- Methoxy-'
Nitrile
M. p.. OC.
Yield,
OC.
%
Obsd.
Lit.
0 30 0 30 0 30 30
38 1 33 48 25 41 45
139-140 126-127 85-88 93-94 56-57 53-54
