Oct., 1950
COMMUNICATI~ )NS TO THE EDITOR
acid anhydride (111). Identity was established by a mixed melting point determination and by comparison of the ultraviolet absorption spectra in chloroform and in aqueous alkali.
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tion of the benzoylainino group is choseu in accord with the findings of Rapoport. e1 nl.,0 and (2) that the B-ring of I may be correctlv assigned to colchicine itself.
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2,3,4 - Triinethoxybenzsuber - 5 - ene - 5,6 - dicarboxylic acid anhydride (111) was prepared by the Boupult cyclization of 3,4.5-(CHrO)rCsH,(CHz),CH(C0OGNs)COCOOCzHs which was obtained by two different routes. (A) Ethyl 3,4,5-trimethoxybenzoylacetate was alkylated with ethyl 6-bromopropionate and the resulting ester was hydrolyzed to yield y-(3,4,5-trimethoxybenzoyl)butyric acid. The keto-acid was hydrogenated5 with a palladium-carbon catalyst to y-(3,4,5-trimethoxypheny1)-valeric acid (in. p. 6849"; reported' m. p. 70"). This acid was converted to the ethyl ester (with ethanol-sulfuric acid) (b. p. 151' at 0.3 mm.). (Anal. Calcd. for CaHz4Os: C, 64.59; H. 8.11. Found: C, 64.83; H, 8.32.) Condensation of this ester with ethyl oxalate gave an enolic ester which was cyclized with sulfuricphosphoric acids to yield the anhydride I11 (m. p. 119.5-120'). (Anal. Calcd. for C I E H ~ E OC, ~: 63.15; H, 5.30. Found: C, 63.28; H, 5.59.) (R) A Reformatsky reaction with 3,4,5-trimethoxybenzaldehyde and methyl y-bromocrotonate yielded an olefinic ester which was hydrogenated (palladium-carbon catalyst) to provide a saturated ester. From this ester, which was not obtained in analytical purity, it was also possible to prepare I11 by condensation with ethyl oxalate, followed by cyclization. Degradative,' spectroscopic,' and synthetic' data are now available which show that the conversion of N-acetylcolchinol methyl ether to dihydrodeaminocolchinol methyl ether Via the deamino compound does not involve an alteration in the size of the seven-membered B ring. Further, both N-acetylcolchinol and colchiceine (the Nacety' analog of N-benzoyltrimethylcolchicinic acid) can be oxidized to the same product,&presumably N-acetylcolchinic anhydride. From this i t may be concluded (1) that N-benzoylcolchinic anhydride has the structure I, in which the posi-
RESEARCH DIVISION SUITH,KLINEAKO FRENCHLA"ORATORIIW 1530 SPRIXOARDSSST. PIIII.AI)I'I.PIlI*,
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EIGHT LIQUID PHASES IN STABLE EQUILIBRIUM
Sir: Hildebrand' has reported the construction of a system of seven liquid layers in stable equilibrium. This system consisted of heptane, aniline, water, perlluorokerosene. white phosphorus, gallium and mercury. The authors have discovered that an eight-layer system can be constructed by a suitable modification of the Hildebrand system. The eight layers (in order of increasing densities) are paraffin oil, silicone oil, water, aniline, perfluorodimethylcyclohexane,white phosphorus, gallium and mercury. After mixing, the eight layers reappear upon centrifuging. The system is stable indefinitely a t 43". This temperature is required to melt the gallium and phosphorus.
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The paraffin oil consists of a mixture of paraffin hydrocarbons from CaHW to GaH,,. A Dow Corning silicone oil' was used; it is referred to by (1) Aildcbr.nd. J. Phyr. Cdlold Chrr.. U. 844 (1949). (2) Do- Coraial Slli-a Natabook. Fluid .%As, N a m h S, 21 (1048).
the inanufacturer as DC 200 and has a viscosity of 1000 centistokes a t 25". The peduorodimethylcydohexane was obtained from Halogen Chemicals, Inc., Columbia, S. C. Its isomeric composition was not specified. MARQUETTE UNIVERSITY SCOTTL. KITTSLEY
I t is apparent that the organolithium compound retained its configuration a t - 70°, but racemized when the temperature was raised to 0". The pphenylphenacyl ester derivative (from acid A) melted at 59-60' after five recrystallizations and showed a rotation of [ C Y ] * ~ D-2.8" (0.0515 g./cc. MILWATJFCEE 3, WISCONSIN HERBERT A GOEDRY benzene, 1 = 1). A mixed melting point with an RECEIVED JTJLY 21, 1930 authentic sample showed no depression. ___ ____ From reported rotations for 2-iodoOctane3" and FORMATION OF OPTICALLY ACTIVE 2-methyoctanoic it is estimated that about 1-METHYLHEPTYLLITHIU'M eighty per cent. racemization occurred in the conSir: version of the iodide to the acid. The configuraThe carbonation of the products from a reac- tional relationships are such that either predomition of s-butyllithium and (-)2-iodooetane has nate inversion or retention must be assumed for led to the isolation of (-1.2-methyloctanoic acid. both the interchange and carbonation reactions We can interpret this fact only on the basis that and 2-iodooctane in pentane in (1) optically active I-methylheptyllithium was thes-Butyllithium absence of ether did not react significantly formed by a metal-halogen interchange reaction over a period of forty-two hours at -77". The and (2) asymmetry was retained during the carthat ether so facilitates the interconversion bonation reaction. Previous attempts to prepare fact suggests that the reaction proceeds by an ionic asymmetric organometallic compounds of this rather than by a free radical mechanism. type have been unsuccessful.' (3a) Pickard and Kenyon, J Chem S O L 99, , 69 ( 1 Y 1 1 ) In a typical experiment, a solution of 18.4 g. of {b) Kothen and Levme, J Ckevs Phys , 7, 975 (1939) 3 1 ) d26r 1.3181, W2'D 2-iodooctane ( ~ ~ ~ ~ -45.86', THECHEMISTRY DEPARTMEVP 1.4861) in 100 cc. of petroleum ether (b. p. 28-38') was added over a two-hour period to a petroleum NORTHWESTERN UNIVERSITY ROBERT L. LETSIYGER ether solution of 320 cc. of 1.04 M s-butyllithium Evilvsro~,ILLINOIS RECEIVED AUGUST21, 1950 and 25 cc. of peroxide free ether a t a temperature Two minutes after completion of this of -70'. addition the mixture was carbonated on Dry Ice From the acid fraction was isolated 14.84 g. of 2- MECHANISM OF THE OXO AND RELATED REACTIONS. 111. EVIDENCE FOR HOMOGENEOUS methylbutyric acid ( a 2 l O.OO', ~ = 2) and 0.66 HYDROGENATION g. of 2-methyloctanoic acid (b. p. 133' at 11 mm., Sir: CY~%D -0.75 * 0.01', 1 = 0.5, n Z 51.4270). ~ It has been shown that the hydroformylation The p-chlorophenylisothiuronium salt of 2-methyloctanoic acid melted at 143.5' after recrystalliza- (oxo) reaction is often accompanied by hydrogenation from dioxane, and the mixed melting point tion; indeed, in some instances hydrogenation with a pure sample of the racemic salt was the proceeds to the exclusion of hydroformylation.1,2 same. Regeneration of the acid from this salt We wish to report evidence strongly supporting yielded a material with undiminished rotation and the view that the hydrogenation is homogeneous and, in this respect, unique. ?Z=D 1.4280.2 The organic portion from the carThree experiments were performed a t 185" bonated products was halogen free, and the highest rotation of any fraction was CY% -0.19, E = with reduced cobalt as catalyst and butyraldehyde as substrate. The catalyst was prepared by 0.5 (for the portion boiling 125127' at 10 mm.). Three subsequent reactions differed in that the treating 9.3 g. of cobaltous formate and 50 ml. iodide was added over a period of twenty minutes of cyclohexane with 2000 p.s.i. of hydrogen a t was carbonated (-4) after one 185' for 2 hours in a stainless-steel autoclave of t -70°, (B) after sixty minutes 500-ml. capacity. An initial partial pressure of ) after warming to 0" over a 2000 p.s.i. of hydrogen was used in each of the twenty minute period. The results are indi- three experiments and the partial pressure of carbon monoxide was varied. cated in the table. a* iodide &D acid In the first experiment, no carbon monoxide (1 = l i (1 = 0 5 ) Reaction was present. The reduction proceeded smoothly, -44.36 -1 18 A and the calculated pressure drop was observed. -41.00 -0 96 B Distillation yielded 57 g. (77%) of butanol-1, -39 8.5 0 00 c b. p. 115.5-117°. In a second experiment, 1000 (1) Tarbell and Weiss, Tms JOURNAL, 61, 1203 (1939); Porter, p.s.i. of carbon monoxide was added (total presibid.. M, 1436 (1936); Schwa- and Johnson, ibid., 118, 1063 ( l 9 3 l ) , sure 3000 p.s.i.). Approximately one mole of gas Pickard and Kenyon, J . Cbrm. SOC.,SS, 86 (1911): Zicglerand Wenz, was again absorbed and 49 g. (66%) of butanol-1, BEY..88,364 (1960); Wittig, Vldal and Bdnwt, Bid., 88,369 (1950); Wallis and Adams, TH18 JOWBNAL, I S , a836 (1933). The evidence b. p. 116-117.5', isolated. The reaction was preof Wallis and Adams fm an asymmetric carbanion was shown to be sumably homogeneous with the soluble dicobalt aroneoua by Wittig, Vidal and Bohnert. I
(2) Tha rcfmctive index of a pursed sample of 2-methylactPnoic add prplvcd from a orl-d reagent WM i 1 8 b 1.4280.
(1) Wender. Levine and Orchin, TEW JOURNAL,72, 4876 (1950) ( 2 ) R, Adkina and 0. h k , ibid., 70,888 (1949).
