NOTES
April, 1957 LCV
TABLE I ~,~-DINITROTOLUENE I N THE PRESENCE OF ADDITIVESAT 54.3’
OF
Concn. of additive (moles/100 moles substrate)
2,G-Dinitrostilbene
0.0 0.5 1.o 1.5 2.0 2.5
10.8 8.2 6.1 4.5 3.35
LCV, cm./min. in the presence of 2,4Dinitrophenylhydrazone benzaldehyde
9.9 7.1 5.3
2,3’,4-Trinitrostilbene
13.7 9.9 7.0 5.1 3.55 2.45
bility, while the other two additives do not. The 2,6-dinitrostilbene follows the Freundlich relationship fairly well, while the 3’,2,4-trinitrostilbene follows neither relationship well over the concentration range studied. D. 2,4-Dinitromesitylene.-Tlie effects of the three additives tested on the LCV a t 74” are given in Table 11. As expected, 2-naphthol showed a very weak effect, 2,4,6-trinitrostilbene a stronger one, and a resinous product prepared by refluxing an equimolar mixture of dinitromesitylene and 4phenylbenzaldehyde (xylene solvent) in the presence of piperidine for several hours shows a strong effect. The resin was assumed to have a molecular structure and weight corresponding to
These additives to the dinitromesitylene system affect the crystallization amording to the Langmuir-type isotherm.
TABLE I1 LCV
OF
DINITROMESITYLENE IN THE PRESENCE ADDITIVESAT 74.0”
Conon. of additive (moledl00 moles substrate)
2Naphthol
2: 4: GTrinitrostilbene
0 0.5 1.0 1.5 2.0 2.5 3.5
45 41.7 39.3 37.0 34.9 32.7 29.4
45 37.6 33.4 30.4 27.4 24.5 20.3
OF
LCV, cm./min. in the presence of Resin
45 19.7 13.0 10.3 8.4
7.2
...
X-Ray Studies.-In addition to merely slowing down the advancement of a single growing face of solid into the supkrcooled melt and thereby decreasing the LCV of a compound, it was thought that perhaps strongly absorbed additives might inhibit the LCV by changing the orientation of the crystals formed from the solidifying melt. To determine this effect, if any, rotation patterns were taken of 2,4-dinitrotoluene without additive and with 2% 2,4,4’-trinitrostilbene which had been crystallized a t about 15” below the melting point in thin-walled glass capillaries (about 0.5 mm. i.d.). The additive was found to decrease the number of crystals and greatly increase the degree of orientation.
509
A similar experiment was made on the same samples contained in smaller (about 0.1-0.2 mm. i.d.) capillary tubes. Single crystals were not obtained, but it was even more apparent than in the previous case how much the orientation of solid was increased by the presence of additive. It appears that this greater orientation is related to the lower LCV of 2,4-dinitrotoluene in the presence of 2,4,1’trinitrostilbene. The Effects of Additives on the TNT System Compared with Effects on Other Nitro-aromatics. -In general, conclusions from the study on the 2,4,6-trinitrotoluene system applied well to the compounds studied in this research. I n all cases, the nitrostilbene additives gave much greater crystal growth activity than previous additives reported in the literature. The iniportance of having one end of the molecule similar to the molecule of the system being inhibited is well demonstrated. Perhaps the greatest difference between T N T and the other systems is the extremely rapid decrease of LCV of T N T with very small concentrations of the stilbene additives, as demonstrated by the large “p” values obtained in the modified Langmuir equation for these additives. This great initial decrease is not observed with less powerful additives such as anthracene in TIST, nor with any additives in the other nitroaromatic compounds studied. The modified Langmuir expression for the effect of additives on linear crystallization velocity, which was applicable to the T N T systems, was found to be not generally applicable to nitroaromatic systems. The only conclusion reached from the data available is that the adsorption of the more powerful additives is a complicated phenomenon and like the adsorption of gases a t higher pressures can follow various differing mechanisms. As the Freundlich and modified-Langmuir equations are both 0 1 1 1 ~ approximate mathematical descriptions of the true phenomena, it is perhaps rather fortuitous when one law is followed over a large range of concentration. Acknowledgment.-The authors wish to express their appreciation to E. C. Lingafelter and R. W. Van Dolah for encouragement and helpful discussions throughout the course of this work. THERMODYNAMIC FUNCTIONS FOR T H E ISOTOPIC HYDROGEN SELENIDES AND HYDROGEN TELLURIDE BYA. P. ALTSINLLER Received November 18, 1966
Although the therniodynamic functions for hydrogen and deuterium and tritium oxides and SUIfides are well e~tablished,l-~ no calculations of the thermodynamic functions of the hydrogen and deuterium selenides nor hydrogen telluride over a range of temperatures appears to be available. While the vibrational frequencies of H2Se, HDSe and DzSe were obtained some years ~ g o , ~ , ~ (1) F. D. Rossini, et al., NBS Circular 500, 1952. (2) A. S. Friedman and L. Haar, J . Chem. Phys., 2 2 , 2051 (1954). (3) L. Haar, J. C. Bradley and A. 9. Friedman, J . Research Natl. Bur. Standards, 86, 285 (1955). (4) A. Dadieu and W. Engler, Wiener dnzeiger, 128, 13 (1935). ( 5 ) D. M. Cameron, W. C. Sears and H. H. Nielsen, J . Chem. Phus., 7, 994 (1939).
NOTES
510
Vol. 61
TABLE I1 the molecular dimensions of these molecules have FUNCTIONS FOR HYDROGEN DEUTERIUM been determined only recently.6J The vibrational THERMODYNAMIC frequencies used in calculating the thermodynamic IN THE IDEALGASSTATE IN CAL./DEG./MOLE SELENIDE H o - Ho' - F o - HQ' functions are HzSe: v1 = 2260, vz = 1074, v3 = T so T CP" T,OK. 2350 em.+; HDSe: VI = 1691, v2 = 905, v3 = 38.21 46.16 7.95 100 7.95 2352 em.-'; D2Se: VI = 1630, vz = 745, v3 = 1696 43.73 51.70 7.97 200 8.08 ~ m . - l . ~The molecular dimensions of hydrogen 45.51 53.52 8 . 0 1 250 8.26 selenide are r(Se-H) = 1.460 f 0.013 A. and 54.31 8.04 46.27 275 8.37
