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Vol. 76
one of the set Pci2c, P6smc and PB~/mmcrequiring there are two alternative configurations to be conthe glide plane vanishings 1 hh.1) for 1odd. No such sidered. The four chlorine and the four fluorine reflections were observed, but a total of only 21 atoms give two bisphenoids having a corntiion cenforms of all types could be recorded. However, a ter, the one elongated the other flattened along the threefold axis (and additional symmetry) will be unique axis. Probably there are two not very different minima in the niolecular energy correspondrequired of the molecule in any case. Rigorous application of space group theory re- ing to the assignment of chlorine atonis to o m or the quires every atom to have a single equilibrium po- other bisphenoid. The packing shapes of the two sition; assuming further only that discrete mole- configurations, as formulated by analogy with cules of the assigned composition exist in the crys- c4c&and C4F8, are quite different. Either gives tals we arrive a t the following conclusions. No dis- easy packing relations within the unit cul-e for crete molecule having just four atoms of one kind, many but not for random orientations of adjacent e.g., 4C1 in C4C14F4 or C8C14F8,can have the symme- molecules. Perhaps inversion of moleciilar contry of m3m or 43. Further, no molecule C4CI4F4or figuration between the two extremes plays an itnC&&F8 of chemically reasonable nature can meet portant role in the mechanism of “rotation” in the the requirements of 43m; in particular, neither a crystal; a further study utilizing data from the cyclobutane nor a tricyclooctane framework, how- purified isomer might be quite profitable. Based upon the formulas with condensed rings ever distorted, can do so. Nor does it seem possible to devise a configuration with threefold sym- for C6F10and CsC14Fs, packing models having an asmetry which is also chemically plausible for a mole- sumed angle of folding of 120’ between rings sharing cule C6FlO. Certainly the bicyclohexane franie- an edge (with or without puckering of the individual rings) appear to give packing relations within the work cannot have a threefold axis. We conclude that for all three substances the respective cells much like the case of C4C14F4; cermolecules in the crystal must have sufficient rota- tain molecular orientations give easy packing relational mobility to give the observed diffraction tions, but reorientation must involve a codperativc symmetries as statistical averages over groups of mechanism. We may conclude that the bond diacells containing molecules in various orientations. grams suggested by the methods of synthesis are Previously cited data on the Bragg intensities, the not inherently improbable in terms of our strucdiffuse background scattering, and the physical tural data. properties of the crystals support this conclusion. We wish to thank the Atomic Energy CommisHowever, the “molecular rotation” cannot be sion for support of this w o r k u n d e r Contract No. unhindered as is shown by direct experimental evi- AT(30-1)-578 with Cornel1 University. dence of the following sort. Were the rotation BAKERLABORATORY OF CHEMISTRY entirely “free” the effective electron density in the CORNELL UNIVERSITY NEW YORK molecule would be independent of angular vari- ITHACA, ables, ;.e., be spherically symmetric, and the reflection intensity would be determined by the value Studies in Low Concentration Chemistry. VIII. of the quadratic form. But, for example, in c&&of Tracer Yttrium, Antimony and Fs (333) has several times the intensity of (511), Some PropertiesSilver in Solution and (551) is far more intense than (711). A slightly BY GEORGE K. SCHWELTZEFAND W. MORRISON JACKSON different analysis applies to the several possibilities for placing two molecules of C6F10 within the hexRECEIVED JANUARY 8, 1954 agonal unit. Unrestricted rotation of the molecule The purpose of these experiments was to investiabout the threefold axis (cylindrically symmetric gate the radiocolloidal properties of several ions in electron density) would in every case require a characteristic extinction of certain reflections which very low concentration solutions. Yttrium-00, are experimentally recorded. The existence of a antimony-125 and silver-11 1 were used as tracers. Experimental restricting potential of appropriate symmetry can Solutions.-Solutions of yttrium-90 0.01 N in hydroscarcely be doubted; the strong coupling of rotachloric acid and silver-111 0.01 N i n nitric acid were prepared tion with lattice vibrations is indicated. previously reported methods.’ A solution of antimonyIire have not attempted to calculate Bragg in- by 125 0.01 N in hydrochloric acid was prepared by dilution of tensities from an assumed model. Except possibly a stock solution obtained from the Oak Ridge National for C4C14F4,our lack of definite knowledge of the Laboratory. The concentrations of the yttrium and silver M and about were established as below equilibrium molecular configurations makes the solutions M by spectrographic analysis,’ and the concentration of the problem a poor choice for study of molecular rota- antimony was established a t about lo-’ A l by a microchemition; and, in contrast with the diffuse background, cal test by Feigl.3 Techniques.-Adjustments of pH, sample preparations, the Bragg intensities are not mficient!y sensitisre radioactivity measurements, as well as filtration, centrifuto details of the model to promise a strong case for gatiqn and adsorption techniques have been described in a a particular assumed configuration. The simplest previous paper.‘ The main difference in procedure is that case of C4CI4Fais probably quite complex. Assum(1) G. K.Schweitzer, B. R. Stein and W.M. Jackson, THIS JOURNAL, ing that we have the stable isomer and that the cy- 76,793 (1953); G. K. Schweitzer a n d J. W. Nehls, ibid.,74,6186 (1952). clobutane ring is markedly puckered as in C ~ C I S ~ (2) Private communications from J. H. Gillette, O a k Ridge National a n d T. DeVries, Purdue University. and C4F87to give a molecule of symmetry D 2 d , Laboratory, (3) F. Feigl, “Laboratory Manual of Spot Tests,” Academic Press, (6) T. B Owen a n d J L H o a r d , A c f a C r y s t , 4, 172 (1951) (7) H F. Lemaire a n d R L. Livingston. THISJ O U R N A,I 74, 5732 1952).
I n c . , N e w York, N. Y., 1943. ( 4 ) G. K. Schweitzer and W. N. Bishop, THISJ O U R N A L . 75, 6330 (1953).
June 20, 1951
COMMUNICATIONS TO THE EDITOR
nitric acid was used for the adjustment of PH with the silver solutions. Purification.-Acidic tracer yttrium solutions were centrifuged, filtered through ultrafine Misco Metallic Filters, or filtered through ultrafine Selas Bacteriological Filters in an attempt to remove suspended impurities. All these experiments were performed in a dust-free atmosphere and all apparatus was washed with centrifuged or filtered water. After centrifugation or filtration, the pH values of the solutions were adjusted with centrifuged or filtered sodium hydroxide solution, and then the solutions were centrifuged for 30 minutes. Samples taken from the solutions before this final centrifugation and after centrifugation were counted and used t o determine the percentage of yttrium removed.
Filtration and centrifugation of labeled silver solutions a t a p H value of 8.0 showed that 55 and 2075, respectively, of the silver was removed a t hl and below and that practically all the silver was separated a t lod5M and above. Conclusions The use of previously purified yttrium solutions in filtration and centrifugation experiments yielded results similar to those obtained with solutions which had not been purified. Adsorption of tracer yttrium onto Norit A carbon as a function of p H differed from the trend shown in centrifugation or filtration. The presence of carbonate does not alter the adsorption behavior to any marked degree, but has 3 profound influence upon removal by filtration.' These observations lead to the conclusion that adsorption of yttrium upon impurities suspended in solution is probably not the major factor involved in the formation of radiocolloids. Some removal of tracer antimony from its solutions can be realized by centrifugation or filtration, maximum removal occurring in the neutral region. The antimony probably existed partly as a radiocolloid and partly as chloro- or chlorohydroxocomplexes at all PH values. Adsorption results showed no similarity to the centrifugation experiments, leading to the conclusion that there is probabiy no reiaiion. The results in the silver experiments are what one would expect on the basis of true colloid formation and not for adsorption of silver ions onto suspended
Results Centrifugation of yttrium solutions which had not been purified gave results in agreement with previously reported values using filtration.6 Up to a p H value of 5.0, no yttrium is centrifuged, then the removal increases almost linearly with pH up to a p H value of 7.0, a t which 100% of the yttrium is removed. The percentage removed remains a t 100% for higher p H values. No differences were noted when the previously purified yttrium solutions were used. Adsorption of tracer yttrium onto Norit A carbon goes from 0% a t a pH value of 0.0 to 100% a t a p H value of 5.0, the percentage adsorption then remaining a t 100% up to a pH value of 12.0. The presence of carbonate had little effect upon the adsorption. The antimany saluiicms were GLtered a d rentrifuged a t pH values from 1.0 to 12.0. From a PH value of 1.0 to S.0 the percentage antimony filtered rose from 15 to 30% then dropped to 20% a t a p H value of 12.0. The centrifugation curve was almost identical in shape, but was about IO percentage points lower. Adsorption of antimony on Norit A increased from GO% to a p H value of 0.0 to 95% a t a pH value of 5.0, then dropped to 34% a t a pH value of 10.0, remaining here up to a p H value of 12.0.
;aDur;ties.
Acknowledgment.-The authors wish to express their gratitude to the U. S. Atomic Energy Commission for Research Grant AT-(40-1)-1058 which supported this work.
( 5 ) J D Kurbatov and M. H. Kurbatov, J Phys. Chem , 46, 441 (1042); 0 K Schweitzer, B. R Stein and W. M. Jackson, THIS JOURNAL, 75, 793 (1953).
DEPARTMENT OF CHEMISTRY UNIVERSITY OF TENNESSEE 16, TENNESSEE KNOXVILLE
COMMUNICATIONS A NOVEL REARRANGEMENT IN THE SYNTHESIS QE AZULENES Sir :
In the course of work which had as its goal the preparation of 4,7-disubstituted azulenes by a method designed eventually to lead to azulenes derivable from natural sources, 2-methylbicyclo(5,3,0)-5-decanone (I), b.p. 92-96' (2.5 mm.) (Calcd. for CllH180: C, 79.46; H, 10.92. Found: C, 79.64; H, 11.02); semicarbazone, m.p. 143143.5' (Calcd. for C I ~ H ~ ~ N ; C, O : 64.54; H, 9.48; N, 18.82. Found: C, 64.58; H, 9.48; N, 19.0) was prepared- as- f0llota:- Cydopentaxrcm~carboxylic ester was condensed with ethyl ybromo - y - methylcrotonate; rearrangement a t this stage is excluded by consideration of the infrared spectrum of I (bands a t 1705 and 1385
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THE EDITOR
crn.-l),l The ncn-enclic character cf the ccndensation product, demonstrated by chemical tests and infrared spectrum, eliminates another, though unlikely, isomerization occurring via reversal of the Dieckmann reaction and recyclization in the other direction. Reduction, hydrolysis and decarboxylation furnished an acid whose ethyl ester was condensed with ethyl cyanoacetate. The condensation product was reduced, hydrolyzed and decarboxylated and the resulting dibasic acid cyclized to I through the barium salt. (1) An SNZ type rearrangement, would have led to a bicyclo(3,3,0)octanone derivative possessing a band near 1735-1750 cm. -1. A shift from a,@-to @,y-typeunsaturation in the crotonic ester during bromination, which might have led to a &bromo compound, would have resulted in the formation of bicyclo(6,3,0)undecanone and elirninatlafl d thu *CHI band at 1848 wn. wbkb appears in e l l eufutrttuadll,
