~CONTRIRUTION PROM THE RESBARCH LABORATORY OP PARKE D A V I S .4ND C O
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PERIODIDES OF CAR ONPL ~~~~~~N BY A RIL. CLOVER Received March 19, 1920
Some years1 ago the writer showed that several diflerent types of organic substances, all possessing the carbonyl group in common, united readrly with iodine and potassium iodide to form fairly stable triple addition compounds which crystallized readily, weie possessed of a strong metallic lustre and could easily be separated into their components. Pure compounds were prepared with benzophenone, benzoic anhydride and other anhydrides, and it was pointed out that there was evidence of the existence of similar compounds of benzanilide and of methyl oxalate. Careful analyses of several of the pure compounds showed that the formulas of some were relatively simple while those of others were complex; and it was also found that a different combining proportion existed for each of the different bodies which were amlyzed. In no case was a perfectly stable substance found, that is, there was always noted a t least a slow disengagement of iodine a t ordinary temperature and in all cases the iodine of the compounds was readily removed by means of very weak reducing agents. The results which were obtained in this former investigation naturally brought to mind the well known class of periodides of the alkaloids and other organic bases, Concerning the structure of the periodides derived from these strongly basic substances and the essential function of the nitrogen in their constitution, there can bc little doubt. When we compare these with the compounds referred to in the previous paragraph, we find that in the latter case we hat-e generally nonbasic, or at the most, feebly basic substances which may take on a metallic iodide in place of the hydriodic acid oi an alkaloidal salt, a further addition of io&.ne in either case giving rise to periodides, or bodies containing loosely combined iodine. It becomes clear that there must be a fundaniental difference between the carbonyl periodides and those derived from strong bases. In 1891,Scholvien2 described a substance which Ire supposed to be a periodide of acetophetietidine, having the composition C&b,&Tz0417. This was patented by Riede13 and lrr-rown as Podophmzia. Emery4 has recently shown that the formula assigned by Scholvien is incorrect and lhar the latter had a wrong conception of the molecular structure of iadophenzn. Emery has proved the correct formula of the body to be (CzKs0G6H4NRCQCHa)2I-II.Iq and negards it as an addition compound oE 1 1
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Am. Chem. J., 31, 2 5 6 (1904). Pharnz. Zentralhalle, 32, 311 I i S g i ) . D. W P. 58409, Ber , 25, 2 3 5 Ref. (1892) THISJOUKNAT,, 38, ~ 4 (1916). 0
PE$RIODIDES OE' CARBONYL COMPOUNDS.
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the 3 constituents. He considers it a periodide of the hydriodide of acetophenetidine and classes it with the well known basic periodides. The results of Emery's investigation are not surprising in view of the work of Wheeler axid Waldenl wlio in 1896 showd that acetanilide combines with iodine and hydriodic acid to form the crystalline addition cornyoitsads (G61K~NHCOCHs)~HI.I~ and (C6IIsNHCOCH3)2HI.I4. These compounds they considered analogous to the periodides of substituted ammonimn salts. Wheeler and W alden naturally made no mention of the acetophenetidine periodide of Scholvien and Riedel for, as has already been stated, the discoverers of this substance, through failure to understand its true constitution. had not properly described it. Shortly afterward, Piutti2 in attempting to prepare other periodides similar to the product obtained by Scholvien and Riedel from acetophenetidine, was able to isolate crystalline periodides, which were composed of p-ethoxy- or p-methoxy-phenylsuccinimide, potassium iodide and iodine and represented as foilows (C4P140zl'h*C6HpOC2H6)2.KX .Iz and (C41K*Q2NC6H~OCH3)2.KI .Iz. ]Extending his experiments beyond the scope originally intended, he isolated a similar- crystalline derivative of succinimide to which he assigned the formula (C4Hb02N)4KI.13.This formula has been found by the author to be incorrect, as will appear from the experimental part of this article. However, Piutti undoubtedly isolated a crystalline addition compound hetween suceinirnide, potassium iodide and iodine which was more or less contaminateci with impurities and with 2 of the derivatives of succinimide he isolated analogous compounds which we may assume to have been pure, The discovery of bodies of this type containing potassium iodide in the molecule was of course not expected by Piutti, and he made no attempt to explain their forn?atian. We concluded, however, that the derivatives of a dibasic acid behaved differently from those of a monobasic acid and was misled into this conclusion by assuming the incorrect forrnula of Scholvien. Moore and in 19x4,isolated periodides of benzamide, triple compounds containing as the third constituent sodium iodide, potassium iodide or hydriodic acid. The writer has examined only the potassium iodide compound and as will appear in the experimental part of this article, a difr'erent composition must be assigned to it, from the one given by Moor and Thomas. This is a mat,ter of secondary importance, however, and the work of these authors has shown more clearly the relation existing beiween the periodides of the amide type which had been previously described. They also pointed out that the product described by Curtiud in r8r)o
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Am.
