V O L U M E 22;NO.
1225
9, S E P T E M B E R 1 9 5 0
comparable chemical analyses. Direct comparison with the amount evaporated was not possible because of the absorption during the necessary mixing period in the closed room. The results deviate, on the average, by 8.3% from the amount found chemically, with the spectrometer low in five out of the seven c:tses. Although this accuracy is sufficient for many studies in industrial hygiene, particularly when conventional methods are not suitable because of the complexity of the mixture or the need to take instantaneous samples, further work is expected to result in considerable improvement. A further description of this technique and its application will be published
LITERATURE CITED
(1) Happ, G. P., Stewart, D. W., and Brockmyre, H. F., Am. I d . Hug. Assoc., Quart., in press. (2) Manning, A. B., J. Chem. SOC.,1929, 1014. (3) Messinger, J., BeT., 21, 3366 (1888). (4) Stewart, D. W., “Mass Spectrometry,” Chap. XXXI in “Physical Methods of Organic Chemistry,” 2nd ed., Part 11. A. Weiss-
berger, ed., New York, Interscience Publishers, 1949. (5) Vaughn, T. H., and Nieuwland, J. A., IND.ENQ.CREM.,ANAL. ED.,3, 274 (1931); 4, 22 (1932). (6) Washburn, H. W., “Mass Spectrometry,” in “Physical Methods in Chemical Analysis,” W. G. Berl, ed., Vol. I, New York,
Academic Press, 1950. RECEIVED April 14, 1950.
(1).
Cyclotetramethylene Tetranitramine (HMX)
36.
Contributed by WALTER C. MCCRONE, Armour Research Foundation, Illinois Institute of Technology, Chicago 16, Ill. Interfacial Angleso(Polar). 101 A 101 = 8X” Beta Angle. 103 . Density. 1.96.
OPTICAL PROPERTIES
Refractive Indexes (5893 A.; 25’ C.). 01 = 1.589 * 0.002 ; * 0.002; y = 1.73 0.01. ODtic Axial Andes (5893 A.; 25’ C.). 2V = 20”; 2 E = 33”. Dispersion. Scght’horizontal, T > v. ODtic Axial Plane. 1 0 1 0 : rhc = 30” in acute 8. Si’gn of Double RefraFtion.’ Positive. Acute Bisectrix. y.
@ = 1.594
\
CH2-T
/ I
SO? Structural Formula for 1IUX
f
c
IIMX is a high melting by-product in the manufacture of RDX. The cystallography of H M S is therefore important iu order to recognize this component in IlDS products. I t is also particularly interesting because it exists in four polymorphic forms, each of which can be obtained at will from a variety of solvents by varying the rate of cooling during crystallization. HMX I
The room-temperature-stable form of HMX can be prcpwrd by very slow cooling of solutions of HMX in acetic acid, acetone, nitric acid, or nitromethane. .%gitation favors formation of I.
Figure 2. Orthographic Projection of HMX I1 Molecular Refraction (R) (5893 A,; 25“ C.). R (calcd.) = 58.0. R (obsd.) = 56.1. FUSIONDATA
w
Figure 1. Orthographic Projection of HMX I
CRYSTAL MORPHOLOQY Crystal System. Monoclinic. Form and Habit, Massive crystals showing the forms: prism, { 110 ; clinopinacoid, (010) ; clinodome, [ 011 ) ; agd both the positive and negative hemiorthodomes, [ 101) and 11011.
v(YaY = 1.64.
The three low temperature modifications of H M X transform through the solid phase to H M X IV a t about 156’ C.; hence, the sublimate and the crystals formed on cooling are of the latter modification. Some decomposition occurs during melting a t 279” C. and the preparation should be quickly cooled. The sublimate shows slightly rounded hexagonal pimcoid and bipyramid combinations. All possible orientations are usually shown with a few giving a centered uniaxial negative interference figure. The crystals from the melt show the same random orientations, but again some six-sided outlines can be recognized showing low birefringence and a centered figure. HMX I1
HMX I1 can be prepared from the same solyents as I but with more rapid cooling. It is the stable form from about 115’ to 156’ C. CRYSTAL MORPHOLOGY Crystal System. Orthorhombic
ANALYTICAL CHEMISTRY
1226
Form and Habit. Needles from all solvents with no well developed forms except perhaps prism, { 110 ) ; brachypinacoid (010). Occasional well formed ends are macrodomes, ( 101 }. tnterfacial Angles (Polar). 110 A 'I10 = 116"; 101 A 701 = 43 Density. 1.87. OPTICAL PROPERTIES The optical properties vary from crystal to crystal and even from one end of the same crystal to the opposite end over a narrow range as follows: a = 1.561 to 1.565; B = 1.562 to 1.566: y = 1.72 to 1.54. Optic Axial Angles (5893 A.; 25' C.). 2V = 10 to 30" (red); -8 to 30' (blue). Dispersion. Crossed axial plane dispersion (see table below). Optic Axial Plane. 010 (red); 001 (blde). Sign of Double Refraction. Positive. Acute Biswtrix. y. Molecular Refraction ( R )(5893 A.; 25' C,), q x y = 1.61. R (calcd.) = 58.0, R (obsd.) 55.7.
.
i=
Dispersion of Optic Axial Angle (2E)for Two Different Crystals of HMX I 2E Wave Length, A.
Crystal 1
Crystal 2
7000 6400 6000 5800 5600 5400 5100 4500
17.5' 17.0' 15.5' 10.00 0.00 -9.20 -17.5' -25.5'
23.0' 20.00 16.5' 10.00 1.5' -9.00 -16.50
..
HMX 111
H M X I11 is also obtained from the same solvent rn I and 11, but with much more rapid cooling rates. HMX 111 has only a very narrow temperature stability range around 156" C., if at all, a t atmospheric pressure. CEY6TAL MOBPHOLoGY Crystal System. Monoclinic. Form and Habit. Massive or plates lying on 001 ; the usual forms are rism, { 110); orthopinacoid, { 100); and basal pinacoid, ( 00lp. Interfacial Angles (not a polar angle). 110 A i i o (projection on 001) = 74'.
H M X IV
H M X IV can be crystallized most readily from solvents in which it is only slightly soluble and by very rapid chilling, preferably in small amounts poured over ice. This modification is stable from about 156" C. to the melting point, 279' C.
-
/
-*I
Figure 4.
0.
'-a,
Orthographic Projection of HMX IV
CRYSTAL MORPHOLOGY Crystal System. Hexagonal. Form and Habit. Rods and needles elongated parallel to c with the forms: firsborder bipyramid, ( 1011j ; firsborder prism, { lOT0) ; and basal pinacoid,-( 0001 1. Profile Angle. 37' (lying on 1010). Density. 1.78. OPTICAL PROPERTIES Molecular %fraction ( R )(5893 A.; 25' C.). q x = 1.593. R (calcd.) = 58.0. R (obsd.) = 55.9. Most of the work described above was carried out on a contract between Cornell Universit.y and the Office of Scientific Research and Development during June 1943 to Ju!y 1944. It was described in OSRD Report No. 3014 recently declassified by the Ordnance Department of the Army. Acknowledgment is due to Alfred T. Bloomquist who was technical representative of OSRD Section B-2-A during the progress of this work and to Colonel C. H. M. Roberts of the Ordnance Department for his efforts in regrading this report. C o s ~ ~ ~ s n r of ~ ocrystallographic ss data for this section should be sent t o Walter C. McCrone. Analytical ,Section, Armour Research Foundation of Illinoir Institute of Technology, Chicago 16. Ill.
Analytical and Microchemical Group of Philadelphia Section The Analytical and Microchemical Group of the Philadelphia Section has planned meetings for October, November, and December, to he held a t the Philadelphia Museum School of Art, Broad and Pine Sts. Topics and speakers are:
Figure 3.
Orthographic Projection of HMX 111
Beta Angle. 120". Twinning Plane. 001. Density. 1.82. OPTICAL PROPERTIES Refractive Indexes'(5893 A.; 25' C.), a = 1.537 * 0.002; B = 1.585 * 0.002; y = 1.666 * 0.002; ,8' = 1.583 * 0.004 (in the 001 plane). Optic Axial Angles. (5893 A.; 25' C.). 2V = 75" Dispersion. Strong crossed, v > T . Optic,Axinl Plane. J-010; a A c =E 42" in dbtuse j3. Sign of Doutde Refraction. Positive. Acute l3inw:irix. 7 . Molecular Ildraction ( R )(5893 A.; 25" C.). Vf/aSy 1.597. R (calcd.) = 58.0. R (obsd.) = 55.4.
-
Rapid Microspectrophotometric Procedures Used in Studies of Iron-Containing Proteins. BRITTON CHANCE,University of Pennsylvania. October 3 Coulometric Titrations. JOHN W. SEASE,Wesleyan University. November 7 Methods for Molecular Weight Determinations. R O B ~E. T KITSON,Polychemicals Department, E. I. du Pont de Nemours & Co., Inc. December 5
Optical Society of America. Cleveland, Ohio, October 26 to 23 Fourth Symposium on Analytical Chemistry. Louisiana State University, Baton Rouge, La., January 29 to February 1, 1951 Foqrth Annual Summer Symposium. Washington, D. C.. June 14 to 16, 1951
