Vol. 77
DONALD B. MILLERA N D H.IRRYH. SISLER
499s
for cis-2-butene17 and for two of the methyl rotations in 2 - m e t h y l - 2 - b ~ t e n e . ~ ~ The contributions of anharmonicity to the thermodynamic functions were treated by the empirical method of McCullough, et al.Ig The two empirical mole-' and v = constants 2 = 1.17 cal. de:.-] 1250 cm.-' were selected to give a satisfactory fit to the calorimetric values of the heat capacity over the whole experimental temperature range. Use of Pennington and Kobe's tables'O simplified the numerical calculations. The calculated contributions were insignificant at the lowest temperatures and amounted to 0.2% of the free energy functicin, 1.3y0of the heat content function, 0.5'& of the entropy and 2.1% of the heat capacity a t 1500'K. Thermodynamic Functions.-The vibrational assignment and molecular-structure pnratncters given in the two previous sections were used to compute I I o - II:, the functions ( F O - H;) ' T , (IIO - H:) IT, S" and Cg for 2,3-dimethyl-2-butene for selected temperatures up to 1500°K. These functions are tabulated in Table X . Some values in Table X are given to more decimal places than is justified by their absolute accuracy in order to retain internal (17) J. E. Kilpatrick and R. S. P i t z r r , J . R # Y S t a n d a r d s , 97, 163 (1946). (18) D. W. S c o t t , G . Waddington, J . C S m i t l i :ind 11. A T , IIiiffrnati, THISJ O U R N A L , 71, 2767 (l.
\V;iddinyton, i b 1 0 . . 76, 26G1
consistency within the table. The satisfactory fit obtained with the calorimetric data may be judged by the comparisons of observed and calculated values of So and C,O in Tables VI1 and VI. T H E SIOLAL
TABLE X TIICRVODYNAMIC FCVCTIO\5 2-BUTFUE
-
273.16 298 l i i :300 100 500 (io0 i00
-
6.5.59 fi7.:10 07 42 -'> if)
I::!
79 20 84 43 89.38
- 94.14 - 98.71 - - 103. I 1
800 900 1000 1100 1200 1300 1100 1500
-107.37 - 111.48 - 115,4(i -119.:~0 - 123.03
19.01 19.85 19.91 23 *33 2 6 . 9:; ,
3iJ , 54
34 01 37. 30 10. 3 R
5,200 5.918 5.972 9.331 13.36 18.32 28.81 29. 84 36.35
50.8i)
52.97 51 90
2,s-DIMETHYL-
81,63 27.71 8 7 . 1 5 29.51 8 7 . 3;3 96 95 100 13 114.9ii
,
123 39 131.44 139.09 14G. 30 153.33 159.05 160.26
82.49
172.27 178.02
13.28 4 3 . 2 8 15.96 48.37
OF
50. 5ii 58.16 I X i 01 74.l(i
29.68
37.48 45.04 51.78 57.07 02.78 67.25 71.14 74. 55 77.51 so 08 82 :I:< 34.:;1
Acknowledgment.-The authors wish to thank Dr. J. Rucl Nielsen, of the Physics Department, University o f Oklahoin:i, for his help in having the Iiainan spectrum studied in his laboratory. BARI.LESVILLC, OKI,AHO.\IA
THE 1\fCPIIERSON
CHEMISTRY 1,ABORATORIES
OF
TIIE OHIO STATE ~ J N I V E R S I T Y ]
Observations on the Addition Compound of Silicon Tetrafluoride and Ammonia BY DONALD B. MILLERAND HARRYH. SISLER RECEIVED MAY18, 1935 The addition compound SiFI.2NH3has been prepared in a highly purified form. Its X-ray diffraction pattern has measured, as well as its dissociation pressure over the range of 331.9 to 422.4"K. Observations concerning the susceptibility of this substance to ammonolysis and hydrolysis have been matic.
The preparation of a diammoniate of silicon tetrafluoride was first reported nearly a century and a half ago' and has been discussed in a few publicat i o n ~since ~ , ~ that time. However, the properties of the substance have not been well-defined. I t became necessary, in connection with our research program, to prepare this material and to study some of its properties. We are hereby reporting some of the resulting observations. These fall under the following classifications : (a) susceptibility to hydrolysis, (b) resistance to ammonolysis, (c) vapor pressure measurements, and (d) X-ray diffraction pattern. Preparation and Analysis.-The complex was prepared (method 1) by passing silicon tetrafluoride (prepared by treating a mixture of sodium fluosilicate and silica with concentrated sulfuric acid, and dried b.y passing through concentrated sulfuric acid, glass wool, phosphorus(TT) oxide, ~ ~ _ _ ~
( I ) J. D a v y , P h i l . TYiillS., 102, 353 (1812j). ( 2 ) W.hlixter, A m C k u m J . . 2 , 153 (1881). (3) J . Qierut. F. Sowa and J . N i e u l a n d 'I'frls
(1936)
TOITRK..AI.,
58, i S f ,
and a trap cooled with Dry Ice) into a chamber containing :in excess of gaseous :Lminotii:i. The complex settled out in the chamber as a fluffy, white ponder. A second method (method 11) used for the prepwation involved the freezing out, at liquid air temperatures, of a sample of silicon tetrafluoride, and then freezing out on top of this an excess of ammonia. The cooling bath was then rcrnovetl and the mixture allon-et1 to warm up and the excesq :irnmoiiia to evaporate. The products were analyzed for ammonia by distillation with sodium Iiydroxide into a 4% boric acid solution followed 1)y titration with standard HC1 s o h . Fluorine and silicon determinations were made on the same sample of complex. The sample was added to water and any silicic acid which formed was filtered off and retained. Fluoririe was then determined in the filtrate as lead fluorochloride.4 The filtrate obtained upon removal of the lead fluochloride was evaporated to dryness, taken up in concentrated HCI, and the silicic acid filtered off. This was combined with the previously obtained material and ignited and weighed. The typical product prepared by method I gave the following analytical results: Found: SHo, 23.0, 22.8; Si, 20.8, 20.9, 21.0, 20.8; F, 5 3 . 6 , 50.4, 50.1, 55.7. Calcd. for SiF4.2NH3: NHI, 24.7; Si, 20.3; F, 5 5 . 0 . The ammonia __ analysis is, therefore, low. On standing with 110 sprcial ~~~~~~~
(4) K
Relchrr a n d 1. l ~ : t t l , ) y 7 ' l i u . I n i i i , y s l . 76, A!#
(19511.
ADDITIONCOMPOUNDS
Oct. 3, 1955
OF S I L I C O N
precautions against atmosphere, the product gradually loses ammonia, and after a period of one year the ammonia content had decreased to about 18%. Method of X-Ray Measurements.-Since the ammonia content of the sample prepared by the first method was somewhat lower than theoretical for SiF4.2NH3, i t was decided to examine this product by means of X-ray diffraction. For this purpose samples were ground so as t o pass through a 325-mesh screen and were placed in Pyrex capillaries. A 114.6 mm. Debye-Scherrer camera using CoKa radiation in conjunction with an iron filter was used. A Phillips Metallix Model 5100 X-ray diffraction unit was employed and the films were measured on a Norelco illuminator and a measuring device capable of an accuracy of =k0.05 mm. The relative intensities of the lines were estimated visually. The diffraction pattern of ( NH4)?SiFe.h’H4F was identified by the pattern listed by ASTM5 Card File. The pattern for ammonium fluosilicate was identified both by comparison with the ASTM data and by comparison with an X-ray pattern determined on our equipment on a known sample of ammonium fluosilicate. Heterogeneity of Product Prepared by Method 1.-It was found that the product prepared by method I partially sublimed a t 60-65” in vacuo to yield a sublimate A , with an ammonia content of 24.2% and an unsublimed residue with an ammonia analysis of 17.8%. The residue when heated to 120-130° in vacuo yielded a further sublimate B of nearly the same ammonia content (17.9%). The small amount of residue was entirely nonvolatile even a t the maximum temperature of a M6ker burner. Sublimite B was identified by its X-ray pattern as ammonium fluosilicate. Sublimate A gave an X-ray pattern which contained no lines attributable to ( NHa)?SiFo, “IF, (NH4)2SiF6.NHIFor any other conceivable possible product for which X-ray patterns have been determined. Further, the ammonia analysis of sublimate A agrees well with the formula SiF4.2NHs. Sublimate A, was therefore, assumed t o be pure SiF4.2NH3. The lines found in the X-ray pattern of this substance are reported in Table I.
TABLE I PATTERN FOR SiF4.2”~ X-RAYPOWDER DIFFRACTION d,
A.
I/Iu
so
4.995 4.767 4.450 4.295 3.881 3.614 3.165 3.031 2.608
8 100
8 60 30 50 30 50
d,
A.
2.484 2.402 2.338 2.063 2.000 1.935 1.878 1.Sl4 1.756
I/Io
50 40 30 20 35 20 20 10 10
d,
A.
1.716 1.884 1.670 1.609 1.583 1.495 1.416 1.294
I/Io
8 8 10 10 20 5 7 20
TETRAFLUORIDE AND ,IMMONIA
4999
(NH4)aSiFe and SiOt was interpreted as indicating that hydrolysis of SiF4.2XH3by atmospheric moisture proceeds in accordance with equation 2 and that equation 1 is unimportant in this process. Experiments in which SiFa,2NH3was placed in an excess of liauid ammonia a t 100’ for a Deriod of 7 d a w indicated the SiF4.2NH3 does not undergd any ammonolysis under these conditions. In fact preliminary experiments a t 300” also gives no indication of ammonolysis. Dissociation Pressure of SiF4,2NHs.--hleasurements of the dissociation pressures of SiFp.2NH3 in the temperatu; e range of 80 to 150” were made using a thermostated sample chamber connected to a mercury filled manometer, The sample chamber was submerged in an oil-bath. The system was arranged so that the gas over the sample could be pumped out a t will. At the beginning of a run, the system, while being maintained a t constant pressure, was alternately pumped on and allowed to come to equilibrium until the pressure recorded returned to a constant value after each cycle, thus assuring that foreign gases had been removed from the system. The pressure was then recorded and the temperature raised to a new value, and so on. When the maximum temperature in such a series of readings was reached, the system was once again pumped out so that a new sample of vapor was present in the chamber, and a new series of readings taken as the temperature was lowered stepwise. Dissociation pressure data were taken on two different runs, using samples of SiF4.2NH3 prepared in different sublimations. The data, recorded in Table 11,
TABLE I1 DISSOCIATION PRESSURE OF SiF4.2NH3 T ,OR
P,mm
351,9 354.2 363.2 363.6 364.2 370.4 371.7 383.2 390.2 391.7 395.5 397.9 399.0
1.9 2.0 4.3 4.3 5.0 6.6 7.5 15.7 22.7 25.1 33.5 38.0 39.2
Triala
2D 1D 1D 2D
1u 2D 1D 1U 2D 1D 1U 1U 2U
T,
OK
402.7 403.0 403.7 405.2 407.9 412.3 412.5 412.7 413.0 416.0 421.9 422.4
P , mm.
48.3 49.1 49.7 54.9 64.4 82.2 82.1 82.7 86.3 103.5 136.9 140.3
TrialD
1U
1u 1u 2D 1D
1u 2D 1U 2U ID 1U 1D
1 and 2 refer to the two different samples used. D refers to readings taken on the down part of the cycle; U refers to readings taken on the up part of the cycle.
are quite consistent. Values of In P vs. lOOO/T are plotted Hydrolysis of SiFa,2NHa.-The observations made in in Fig. 1. These points fall on a straight line, the slope of connection with the sublimation of the product of method I suggested that an investigation of the hydrolysis of S i R . 52NH3 and of its volatility should be carried out. A sample of sublimate A (SiF4.2Tu”s) was, therefore, added to a large excess of water and the precipitate of silica which formed 4 -was removed by filtration. The filtrate was then evaporated to dryness a t from 20 to 40”. The resulting solid residue {phich had an ammonia content of 23.5% was examined by S - r a y diffraction and found to consist predominantly of the 3double salt ( N H ~ ) ~ S ~ F C N along H ~ Fwith some ( NH4)*SiFs. We may consider that the ammonolysis of the complex In P, proceeds by such reactions as those indicated by the equa2tions 2SiF4,2NHs 2 H 2 0 & ( NHa)?SiF6 2NHlF f Si02 ( 1 ) 3SiF4.2NH3 2H20 + 2(NH4)2SiF6 s i o l 2”s (2) When the silica is removed and the solution evaporated some of the ammonium fluosilicate crystallizes with the IO00 ammonium fluoride t o form the double salt. T The fact that on standing in air the product of method I slowly loses ammonia to form a mixture of SiFa~2NH3, Fig. 1.-Logarithms of dissociation pressure of the complex plotted against reciprocal of the absolute tempera( 5 ) Alphabetical a n d Numerical Indexes of X - R a y Diffraction P a t ture. terns. American Society f o r Testing Materials, 1%53, p 12
+ +
+
+
+
L. F. ACDRIETH .\KD SHERWOOD F. \VEST
3000 which was used to obtain the value
From this the value of AH for the process SiF4.2NH3(s)--+ SiFd(g) f 2NH3(g) was calculated using the equation
The value obtained was 18.2 kcal./mole. The data in Table I1 can be expressed by the equation In P = 23.06 -
T
8050 - 21.9
[CONTRIBUl'IOU FROM THE
the equilibrium constants were calculated using the expression K = (2/3 P)2(1/3P) = 4/27 P 3 Expressing P in atmospheres rather than mm., we derive the expression 24,150 In Rat, = 53.37 - ___ T - 21.9 where T is the absolute temperature. Then using the relation A F ' = - R T In K , and expressing AFO in kcal./mole we obtain the following expression for the L I F O for the dissociation as a function of temperature
whence
where P is in mm. and T is iu 'I;. Extrapolation indicates that the dissociation pressure would become equal to 700 mm. at about 185". From the dissociation presiures a t various temperatures
DEPARTMENT OF
AEg8 =
r;.
20.2 kcal./mole
(23')
and AflS8 = 1.86 kcal./mole
(185")
COLUMBUS, OHIO
CITBMISTRY A S D CFiEhIICAL E N G I N E R B I U C , U N I V E R S I T Y O F ILLINOIS]
Hydrazides of Sulfuric Acid and their Derivatives. BY I,.
1'01. 77
AUDRIETII AND SITERWOOD
I. Hydrazinosulfuric Acid
F.I Y E S T I . ~
RECEIVED MAY25, I955 Hydrazinosulfuric acid (HSA) was prepared by the sulfonation of hydrazine with N-pyridiniumsulfotiic acid. I t is a monobasic acid ( p k , = 3.85). A quantitative study of the hydrolysis of the acid at 4 5 ' has revealed t h a t HSA is less stable than sulfamic acid under comparable conditions. A 0.3036 Af solution of hydrazinosulfuric acid hydrolyzes completely to hvdrazine hvdropen - sulfate i n 5.B hours at 13". The infrared spectrum of solid HSA indicates the presence of an amnionium type zwitterion.
Introduction Although the chemistry of the aquo ammonosulfuric acids, such as sulfamic acid and sulfamide, has been the subject of considerable study,3 comparatively little is known about the analogous hydrazine compound^.^ Theoretically, it should be possible to synthesize a whole series of compounds which are related to hydrazine as the parent substance in much the same way that the better known aquo ammono derivatives of sulfuric acid have been characterized and related to each other. However, only two of these compounds, hydrazinosulfuric acid (I) HaNNHSOsH, and hytlrazi-disulfuric acid, [-NHSO:IH]2,5 have been described adequately. Sulfainyl (N211a), has hydrazide (N-atninosulf amid e ) , SO2", been described as a very unstable intermediate, ?, appears whereas sulfuryl dihy-tlrazidc, SO?(N2HlI) to be relatively stable.6 N-Substituted tlerivntives of I are better known than the free acid. The present investigation has concerned itself with the stability of aqueous solutions of hydrazinosulfuric acid and its structure in the solid state. It has been found that hyc!razinosulfuric acid is much more susceptible to hydrolysis than sulfamic acid ( I ) Abstrarted from t h e doctoral di,sertation preseiited t , ) thi, G r a d u a t e College of t h e Uiiiversity uf Illinois, 19J.i. ( 2 ) Western Cartridge Company (Division uf Olin hlatliiewin Chemical Corporation) 1:ellow in Chemistry, C n i r w s i t y o f I l l i n < t i q , 1u.5x-10.;4. ( 3 ) For il comprehensive review of sulfamic acid, sulfamide a n d related aqiio ainmr,ii~rsulfiiricacids see: L. F. Audrieth, h f . S\.WI:I, 11. H . S i s l e r and 11. J m e t t a Biitler, Chem. Reus., 26, 49 (1910). ( 4 ) I,. F. Aridrieth and B. A . O g g , "The Chemistry of Hydra?it1r," J o h n W i l e y and Sc,ns, N e w York, N. Y., 1931, pp. 2 2 0 - 2 : ? 2 . (.i) 11. Konrad i i n < l I.. I'ellen.;, B e y . , 69B, 135 (1020). ((i)I C f < ~ t I i r ~ i i :i ~n n t l li. l,av)rki, ibit/,, 4 4 , 3%i ( l < l l l ) .
and that, like the latter s ~ b s t a n c eit, ~exists in thc solid state a s a zwitterion complex. Experimental Preparation of Hydrazinosulfuric Acid.-The Baiimgarten procedure* entailing sulfonation of hydrazine with freshly prepared pyridine-sulfur trioxideg was modified only with respect to recovery of the crystalline acid from an aqueous solution of the barium salt, Ba(S03NJ-13)2.H20. T o 10.0 g. (0.027 mole) of the barium salt monohydrate tli+ solved in 200 ml. of water, 2.83 g. (0.028 mole) of sulfuric acid (96.6c7,) was added dropwise with rapid stirriiig. Immediately after removal of the barium sulfate by filtration, addition of ethanol and ether to the filtrate precipitated 4.50 g . of white, cry.stalline l~ydrazinosulfuricacitl corresponding to a yield of 76.8(,/;,based on thc ~veightof the. Ixtrium salt; m.p. 217-217.5" (lit. 2170).1° Anal. Calcd. for N~FT$303H: S,25.00. Found: N , 25.00. Acid Strength.-Figure 1 depicts the curve obtained for the titration of liytlrazinosulfuric acid with sodium h y ilroxide. The p H of a 0.00745 ,If solution of the acid w a s Found to be 3.02. This leads to a value for A ' , = 1.40 X 1 0 - 4 0 r p K , = 3.85. Stability in Aqueous Solution.-Earlier workers10 had reported (a) that hydrazinosulfuric acid is stable in aqueous solution forming sulfuric acid very slowly, ( b ) that mineral xcids cause slow decomposition in the cold, and (c) that hydrazine and sulfuric acid are formed rapidly on heating. I t became apparent during the course of the present investigation that hydrolysis is extensive both a t elevated temperatures and in the presence of acids in the cold. From the data of Sommer and Weise," who determined the hydrogen ion concentrations of solutions of hydrazine ( 7 ) F. h Knnda and A . J. King. Trm J U U R K A L , 73, 2315 (1951). I S ) P. Dourngarten, B P Y ,59, , 1976 (192G). (01 €1. 11. Sisler and I.. F. Audrieth, "Inorganic Syntheses," Vc!I. IT, ~ I c G r a w - I I i I l Book C o . , S r w Y o r k , N. Y . , 1R46, p. 173. (10) U7 l'raiihe rind 4 . Vwkerorlt, Bpi.., 47, 038 ( 1 9 1 4 ) . (11) 1:. Sommer :ind i; li'ci-e Z . ,t!!c,rt. t i l l < t , v i . C ' l t p i t i . , 94, 817 Il!llO)
