V O L U M E 23, NO. 1, J A N U A R Y 1 9 5 1 Table 11.
205
Rate of Astatine Deposition on Silver in 3 N Perchloric Acid Time, Min. % Deposited
dried in air, and counted for alpha-activity. Although the astatine deposits principally on the to surface of the silver foil, for quantitative results both sides of &e foil were counted for a1ph:iactivity. Typical analytical results are qhown in Tables T a n d I I. SU&lnfAHY
transferred to a porcelain counting dish. After drying a t 70' ( ' , the dish is counted for alpha-activity. Typical results f n r R series of different tissues are shown in Table I. The principal objection t o the tellurium coprecipitation met hod is the time required in centrifuging, washing, and transferring thc
roprecipitant. To obtain a more rapid analytical procedure, other chemical properties of astatine were studied, particularly its deposition on metallic foils which may be measured for alphaactivity directly. Although astatine is chemically similar t n iodine, the lighter halogen homolog, it also shows definite metrrlllr properties. The similarity between adjacent elements in the lad rows of the periodic table is marked and astatine shows a (510sfi resemblance t o polonium in marly of its properties (1, 1,6). I k pause polonium may be quantitatively removed from dilute arid b i deposition on silver ( 3 ) , a similar study was made with aPt:itine. It n a s found that astatine in biological material may bf, quantitatively recovered by deposition on silver foil from a 3 \perchloric acid solution after organic material has been oxidizrrl bv the perchloric-nitric acid digestion. Determination of Astatine by Deposition on Silver Foil. A sample of astatine-containing tissue is digested in a mixture of perchloric-nitric acid as in the tellurium procedure. After digastion is complete, the solution is eva orated until the perchloric acid fumes (approximately 10 m l j , diluted to 3 N with the addition of distilled water, and transferred to a 50-ml. beaker A circular silver foil 2 mils thick of a size convenient for alpha counting is placed in the bottom of the beaker and the solution iz stirred for 30 minute8. The foil is washed in water and aretonc,
i i i 1)ioIokc:il I'roceciurrs for the riitliocheniic:il analysis of material are described. Organic suhstitnces can he destroyed hv perchloric acid-nitric acid digestion without lose of astatine 1 1 1 . volatilization. .istatinel may hc imlated for alpha counting froin R 3 .V pwchloric acid solution of the oxidation product, t)y miprecipitation with nietallir tc~lluriunior deposition on silvcbr foil. Both procedures may be uscd for quantitative analy,qis. Th(s silver foil method is simpler, requires less time, and is mor(. easily adapted to routine clctrrniinc+tinnsn.here large i i i i i i i t r t w of t i w i f h s are to bt. analyzvil.
ACK~OU'I,F:DGJMENT
The authors wish to thank It.. F. Leininger for his i i i a ~ t yht~1~)i'uI suggestions, Thomas Putnam, G. H. Rossi, and the crew of t,ht: 60-inch cyclotron, and 1l;tlcolm W(.hh for his assistance in dvsisning the target awenihly. LI1'ER.ITPRE CITED (1'1
('orson, D. R., JIacKsnzie. K. R . . and Segre, E., P h y s . Rw.. 57,
439 (1940). ( 2 ) Ibid., 58, 672 (1940). (3) Erbacher and Phillip, 2. Phys.. 51, 309 (1928). (4) Hamilton, +J. G., Asling, C . I\-.. Garrison, W. hi., Scott, K. G., and Axelrod-IIellei. I)., Prric. SOC.E z d . B i d . Med.. 73. :pi (1950). ( 5 ) Hamilton, J. G., and P n l ~ p .If. H., PTOC. XatE. Acad. S c ? . . 26, 483 (1940).
( 6 ) Johnson, G. L., Leinineel R . F..and Segre, E., J . Chem. I'hi/s., 17, 1 (1949). ( 7 ) Kelley, E. L., and Segre, E., Phys. Reo., 75, 999 (1949). I
RECEIVEDJune 26, 1950. Based on work performed under Contract
Yo
W-7405-eng-48 for the Atomic E n e r g j Commission.
40. Nitroguanidine Contributed by WALTER C. MCCRONE Arniour Research Foundation, Illinois Institute of Technology, Chicago 16, Ill. ~ X C E L L E N T crystals
of nitroguariidine can be obtained fruin
EA water by slow cooling. Crystals from a drop of water on microscope slide are usually too h e to be used. Ketones and :I
alcohols have been reported to form addition compounds with nitroguanidine, although crystallization from these solvrnts has been suggested a8 a means of obtaining equant crystals which have higher bulk dendties (3).
CRYSTAL MORPHOLOGY Crystal sytem. Orthorhombic. Form and Habit. Elongated rods sho%ing forms { 1101 rind f 301 } and when massive, 010 1. AGal Ratio. a:h:c: = 0.708: 1:0.143; 0.713: 1:0.146 (I). Interfacial Angles (Polar). 301.4 501 = 63'. Cleavage. Parallel to c. X-RAYDIFFRACTION DATA Cell Dimensions. a = 17.58 A.; b = 24.84 8.;c = 3.Fj8 .I.; n = 17.47A.; h = 21.50.2.: c = 3.59A. ( 2 ) . Principal Lines
Structural Formula of Nitroguanidine Although Bridgman reports poljmorphism for nitroguanidine at a temperature less than 150" c'. under a pressure less than j0,OOO kg. per sq. cm., thcw is no evidence of polymorphisni nt ntmospherir pressure.
d
IIIl
d
I/Il
7.139 6.172 5.579 6.074 4.390 4.144 3.584 3.221 3.081 2.985 2.920 2,732
0.03 0.02 0.01 1.00 0.10 0.80 0.65 0.02 0.02 0.02 0.60 Very n e A k
2,650 2.484 2.384 2.313 2.208 2.174 2.128 2.069 2.011
0.65 Very weak 0.70 Very weak
1.900 1.869
Very weak 0.10 0.10 0.50 0.01 0 02
ANALYTICAL CHEMISTRY
206 e
Formula Weights per Cell. 16. Formula Weight. 104.07. Density. 1.76 (flotation); 1.78 (x-ray); 1.81 (x-ray) (a), Soldate and Noves have also publishpd x-rav powder ditfrae~. tion data for nitroguanidinc (4). OPTICAL PROPERTIES Refractive Indices (5893 A,; 25' C.). a = 1.526 * 0.002; 1.530 * 0.005 (8). B = 1.694 * 0.002; 1.715 * 0.005 (a). y = 1.81 * 0.01. Optic Axid Angle (5893 A,; 25" C.). 2 V = 80'; 74' (2). Dispersion. Very neak. Optic Axial Plane. 100. Sirnof Double Refractiori. Sopatibe. Acute Bisectrix. a = c. 2Molecular Refraction ( E ) (5893 A.; 25' C.). d e P y = 1.673 * 0.005. R(ealcd.) = 25.2. R(obsd.) = 22.2. C
rs
b
C
d
E
Figure 2.
Crystals of Nitmguanidine
From water on SlO" -ling From acefone on slow cooling From sublimation from one alids to anotlmr d . From melt after oomplefe melting
a. h. c.
ACKNOWLEDGMENT
a
1
L9h Figure 1. Orthographic Projection of Typical
Crystal of Nitmguanidine
FUSIONDATA. Kitroguanidina sublimes before melting to give a few separak5 distinct crvstals, hut more representative are the long fibrous ITkds usuallv kith characteristic cross mrkings. Melting occurs a t 246-247" C. with considerable decomposition. If the melting prcmess is stopped ahort of completion, the long fibers formed%$ SIiblimation are elongated parallel to c and show either a obtuse biseotrix figure. More completely melted ~ I W L B crvstallise as fine-needle aggregates in s terracelike pattern charaokenistic of conipounda that mrlt with decomposition.
It is B pleasure to acknowledge the help oi John Krc, who carried out the singlecrystal x-ray measurements of the cell dimensions, and Ann Ihmphreys, who made the powder x-ray measurements. This description is based OLI preliminary work carried out a t Cornell University under contract OEMsr-193 with the O.S.R.D. during 1943-44 under the direction of Alfred T. Blomquiat. John H. Andreen and Sien-Moo Tsang &re associated with this project and contributed t o the above rlruoription. LITERATUHF. C I T E D
(1) Bridgman, P.W., PTOC. Am. Acad. A ~ t Sci., 8 72. 227 (1938) (2) Doll. J., snd Grison, E., Compt. rend., 226, 679 (1948). (3) Pritehard, E. J., and Wright, G. F.,Con. J . Resear&, 25F, 257 (19471~ ~. ..,. (4) Soldate. A. M.. and Noyea, R.M., ANAL.CHEM.,19,442 (1947). C o ~ ~ n i a n ~ r ooi i r orystsliographic s data for this section shovld be sent tu Wdter C. MoCmne, Analytical Swtion. Armour Researoh Foundation of IIiinobInstituteof Technology,Chicago 16, Ill.
