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COMMUNICATIONS TO THE EDITOR
Deaks a t 3.29, 5.89 and 11.56 u (>C=CH,’I.
VOl. 79
at
On treatment with boron trifluoride etherate and a trace of water,4however, it is converted to a white crystalline solid, m.p. 300’ (d.). This new sub’Cipon- quantitative hydrogenation over Adams stance is insoluble in ether, chloroform or benzene, catalyst I absorbed three equivalents of hydrogen but can be dissolved in methanol and subsequently simultaneously. Formaldehyde, isolated as its recovered. It is reconverted by potassium cyanide dimedone derivative, was obtained upon reductive to (I). The analysis of the compound indicates ozonolysis of I. The triene rapidly added two that it is 1,2,3-triphenylcyclopropenylfluoborate equivalents of bromine a t room temperature, (11,X=BFI) contaminated with the hydroxyfluogiving rise to the tetrabromide VIII, m.p. 118-119’ roborate (11,X = BF3OH) ; (calcd. for C21H&F4: (eff.). Anal. Calcd. for Cl8HI4Br4:C, 39.31; H , C, 71.21; H , 4.27; F, 21.46. Calcd. f 0 r C ~ ~ H 1 ~ B F 3 0 : 2.57; Br, 58.13; mol. wt., 549.9. Found: C, C, 71.62; H, 4.58; F, 16.18. Found: C, 71.03, 39.01; H, 2.37; Br, 58.36; mol. wt., 509.2. VI11 71.18; H,4.56,4.38; F, 17.80, 18.31). in CHCls showed Amax 288 mp (log E 4.29) in the Consequently, the fluoroborate has been converted ultraviolet, consistent with a disubstituted cis- to a picrate, m.p. 195-196’ (11, X = C6H2N307); stilbene chromophore, and weak absorption a t (Calcd. for C27H17N307: C, 65.45; H, 3.46; N, 6.08 ,u in the infrared, attributed to the conjugated 8.48. Found: C, 65.50, 65.67; H, 3.55) 3.50; tetrasubstituted double bond. N, 8.59, 8.71). This compound is bright yellow, Acknowledgment.-This investigation was sup- indicating the presence of picrate ion, and is ported by a National Science Foundation research insoluble in benzene or ether. It is quite soluble in ethanol or methanol, however. While i t can be grant, for which the authors are deeply grateful. recovered from these solutions, prolonged standing THEBAKERLABORATORY O F CHEMISTRY CORSELLUSIVERSITY A . T BLOMQUIST leads t o some decomposition. ITHACA, NEW YORK YVONNEC. MEINWALD Thus the s-triphenylcyclopropenyl cation is AUGL-ST6, 1957 RECEIVED relatively stable, due of course in part to conjugation of the three phenyl rings with the positive charge. That it has some reactivity, as evidenced SYNTHESIS OF THE S-TRIPHENYLCYCLOPROPENYL by the slow decomposition in alcohols, may be in CATION part due to the strain resulting from the presence Sir: of three trigonal carbons within a three membered h h c h of the interest in the field of non-benzenoid ring. aromatic compounds centers around attempts to Acknowledgment.-The author wishes to acverify theoretical predictions that certain conjugated systems will be especially stable, or “aro- knowledge generous financial support by the du matic,” while others will not. These predictions Pont Company. (4) This procedure is based on a known method for preparing t h e indicate that, in addition to well-known aromatic cycloheptatrienyl cation (M. J. S. Dewar a n d R Pettit, J . Chem Soc systems containing six electrons and more, a three- 2026 (1956)) membered ring containing two electrons, the cy- DEPARTMENT OF CHEMISTRY UNIVERSITY ROSALDBRESLOW clopropenyl cation, should also be aromatic.’ We COLUMBIA wish to report the first preparation of a derivative NEW YORK27, N. Y. RECEIVED AUGUST 16, 1957 of this simplest aromatic ring. Reaction2 of diphenylacetylene with phenyldiazoacetonitrile yields 1,2,3-triphenyl-2-cycloproCRYSTALLOGRAPHY OF OCTACALCIUM pene carboxylic acid nitrile ( I ) ; m.p. 145-146’ PHOSPHATE (calcd. for C22H16N: C, 90.07; H , 5.13; N j 4.77; Sir: mol. wt., 293. Found: C, 90.22; H, 5.43; N, Although octacalciuni phosphate (OCP) was 4.91; mol. wt. (Rast), 286). The infrared spec- described long its crystallography is obscure. trum of (I) contains a band a t 4.3 p (C=N) and the Its relationship to hydroxyapatite is confused, ultraviolet spectrum is almost identical with that of and even its existence as a “discrete” compound l,2-diphenylcyclopropene-3,3-dicarboxylic ester.3 was questioned4 recently. An awareness of the The compound is soluble in non-polar solvents possible significance of OCP in agriculture5 and i n such as benzene, and gives no precipitate with biochemical processes prompted a study of its ethanolic silver nitrate solution. I t is thus cova- crystallography. lent. Very thin blades of OCP up to 250p long were Cs& C6Hr C6H5 CsHs prepared by slow hydrolysis of CaHP04.2H2O in a \ / \ / quiescent 0.5 W solution of sodium acetate a t 40”. The acetate solution was renewed when its fiH approached 6.1. The crystals closely approximated the formula Ca4H(P04)3,3H20 reported by Bjerrum,6 the average composition of three prepa(1) J. D. Roberts, A. Streitwieser. Jr , a n d C. \ I . Regan, THIS rations being Ca3.99Hl.02(P01)3.288H20. 7 4 , 4579 (1952). ( 2 ) This is one example of a n e w method f o r synthesis of cyclopropenes, t o be reported shortly. (3) S. F. Darling and E . W . Spanagel, THISJ O C R X A L , 53, 1117 (1931). We have also prepared this compound b y our new method (R. Breslow a n d R. Winter, A7n. Chein. SOL. Meeting Abstracts, S e w York, 1997,in press). JOURNAL,
(1) J. J. Berzelius, Ania., 63, 286 (1845). ( 2 ) R. Warington, I. Chein. SOL.,19, 29ti (1886). (:3) P. W. Arnold, I’vaizs. F a r u d a y Soc., 46, 1061 (19.50). ( 4 ) D . Carlstrdm, A c t a Radiol., Supplement 1 2 1 (1955). ( 5 ) J . R. Lehr and W. E. Brown, Soil S r i . Sac. A i n Proc., in press. (ti) X. Bjerrum. “Selected Papers,” Einar hlunksgaard, Copen-
hagen, 1949, p. 21.5.
Oct. 5 , 1957
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COMMUNICATIONS TO THE EDITOR
OCP has distinctive X-ray and optical properties. I t contributed the “additional” lines in Carlstrom’s3 X-ray pattern for hydroxyapatite. Single-crystal Weissenberg measurements on OCP gave the lattice constants a = 19.7 A., b = 9.59 A., c =6.87 A., CY /3 = 90.7’ and y = 71.8’. Correspondipg constant^,^ 2a = 18.84 A., hydroxyapatite a’ = 9.42 A., c = 6.885 k., a = a’ = 90” and y = GO”, resemble closely those of OCP in the values of b, c and a , which lie in the plane of the OCP plates. Dehydration of QCP a t temperatures below 180” shifted the 18.4-A. line progressively to lower spacings. The line disappeared upon elimination of about two-thirds of the hydrate water. The final pattern was apatitic, intermediate in sharpness between those of tooth enamel and bone. At 220°, CaHP04 appeared also. At 1000°,the products were /3-Ca3(P04)2 and P-CazP207. Boiling water decomposed OCP into an apatite approaching hydroxyapatite in composition, along with a variable amount of CaHP04. Both thermal and hydrothermal treatments sometimes yielded apatitic single-crystal pseudomorphs after OCP, the c-axes being parallel to the c of the original OCP. Certainly a distinct crystalline compound, OCP probably has a layer-type structure, the layers perhaps closely resembling those conceivable in hydroxyapatite parallel to (10.0) but separated by water molecules. OCP is not, however, isostruct u r d with hydroxyapatite. The two probably do not form true solid solutions but apparently form interlayered mixtures. Sl’ithin the layers, the unit-cell constants of hydroxyapatite and OCP resemble those of Ca(H2P04)z.H20, CaHP04,2Hz0, CaC1H,P04.Hz0 and CazH7K(P0)4.2H20.8The known ion parameter^^^^* are also similar. Marked stability of Ca-P04 layers is indicated, Apatites perhaps can accommodate water, carbonates and other materials non-isomorphously between layers parallel to (10.0),thus accounting for carbonation, hydration and “internal surface”ll of apatites. The “apatite” obtained by dehydration of OCP apparently is the most acidic that has been prepared and may be another defect apatite.12 Precipitated calcium phosphates considered as hydroxyapatite by n‘atson and Robinson13have the morphology of either OCP or apatite pseudomorphs after OCP. The morphology of tooth and bone crystallites, as seen in their micrographs, strongly indicates that OCP is involved in the formation of these tissues, probably as a precursor that alters to apatite in place. Determinations of the crystal structures of OCP and acidic apatite thus appear requisite to an understanding of the formation and chemical properties of skeletal tissues. Our confirmation of the presence of OCP in ( 7 ) W. Perdok, Schwciz. Monatschr. Zahnheilkumfe, 63, 249 (1952). (8) Unpublished work by T V A . (Y) G. MacLennan and C. A. Beevers, Acta C r y s l . , 9, 187 (195G). (10) C . A . Beevers and B. Raistrick, N u t w e (London), 173, 542 (19.54).
(11) S . B. Hendricks and W. L. Hill, PYOC. .\-uti. Acad. Sci. U . S., 36, 7.31 (1950). (12) A . S. Posner and A . Perloff, J . Reseavch S a l l . B w . Standuuds, 68, 279 (19.57). (13) 51. L. Watson and R. A. Robinson, A m . J . Anat., 93, 25 (1453).
dental calculus14 (apparently as a higher hydrate), along with CaHP04,2H20and an apatite, suggests that the transitions CaHP04.2H20+OCP+apatite occur in calculus. (14) Segerman, quoted in ref. 12
ITALTER E. BROWS DIVISIOSOF CHEMICAL DEVELOPMENT JAMES R . LEHR JAMES P. SMITH TESNESSEE VALLEYAUTHORITY A. ~ ’ I L L I AFRAZIER M WILSONDAM,ALA. RECEIVED AUGUST19, 1957
PAUCIDISPERSE DEOXYRIBONUCLEIC ACID AND ITS USE I N T H E STUDY OF GENETIC DETERMINANTS
Sir : Deoxyribonucleic acid (DNA) prepared by current methods is heterogeneous with respect to both size and shape. We wish to present the results of a new technique which leads to low molecular weight, essentially monodisperse, biologically active DNA. DNA solutions are passed a t various pressures through an all-glass atomizer. The molecular weight of the DNA is decreased and the distribution of sedimentation coefficients is narrowed to near monodispersity. The figure shows the sedimentation distributions* of two samples (11, 111) I
n
szo, w Fig. 1.-Curve I, original DNA; curve 11, DKA sprayed at an intermediate rate (liquid flow, 0.1 cc./sec., air pressure, 6.6 cm. ): curve 111, DNA sprayed a t a higher rate (see table). (1) A stream of solution issuing from a capillary is allowed t o pass through a cone of air formed from t h e annular space surrounding t h e outlet of t h e capillary. (2) V. N. Schumaker and H. K. Schachman, Biochim. B i o p h y s . Acta,
23, 628 (1956).
