2617
INFRARED STUDIES OF TiC14 WITH AROMATIC HYDROCA.RBONS AR'D ETHERS
Conclusions Both X-ray fluorescence and infrared spectroscopy applied to silicoaluminas covering the complete range of compositions a t different hydration levels have given rather interesting information on the organization of these amorphous materials. 1. Three oxygen environments were determined for aluminum corresponding to octahedral coordinated atoms (C type) and to aluminum tetrahedra sharing corners (A type) or edges (D type). X-Ray fluores-
cence does not directly permit the distinction between these two last modes. 2. "A" type occurs in silicoaluniinas containing lorn amounts of aluminum regardless of the hydration level; (A C) types are found in hydrated samples richer in aluminum and (A D) types in the same samples heated above approximately 400 '. 3. In silicoaluniinas containing aluminum of the D type, the apparent silicon coordination number is smaller than four.
+
+
Infrared and Phase Equilibria Studies of Intermolecular Compounds of Titanium Tetrachloride with Several Aromatic Hydrocarbons and Ethers
by J. R. Goates, J. B. Ott, N. F. Mangelson, and R. J. Jensen Department of Chemistry, Brigham Y o u n g Uniuersity, Prow, Utah
(Receieed A p r i l 17, 1964)
Solid-liquid phase equilibria studies were made on mixtures of TiC14with benzene, toluene, p-xylene, pseudocumene, diphenyl ether, anisole, and phenetole. A previously reported 1 :3 compound in the TiC14-benzene system was not verified. Only the anisole and phenetole systems show solid coinpound formation. Solid compounds of 1 : 1 composition are formedin both the anisole and phenetole systems with melting points of 317.21 and 281.96' K., respectively. Infrared absorption measurements were made on solutions of anisole, p-xylene, and diphenyl ether in TiCL and also on the solid TiC14-anisole compound. These results are consistent with a model in which the bonding in the solid compounds is through the oxygen rather than the aromatic ring.
Previous phase diagram studies have shown that CC1, forms solid compounds with benzene and several of its derivatives.l--'l On the other hand, SiCla and SnC14 do not form solid compounds with either benzene or p-xylene.8 Because TiCh is similar in size and structure to the tetrahalides of the group IV-A elements, it was thought that an investigation of this group IV-B tetrahalide with aromatic compounds of varying electron density in the ring would be interesting. This paper reports the solid-liquid phase properties of solutions of TiC14 with benzene, toluene, p-xylene, pseudocumene, anisole, phenetole, and diphenyl ether.
Experimental Chemicals. The starting materials were all reagent grade or better. They were further purified by fractional distillation in a 40-em. vacuum jacketed distilla.(1) A. F. Kapustinskii, BUZZ.Acad. Sci. U S S R , 435 (1947). (2) L. Ebert and H. Tschamber, Monatsh. Chem., 80, 473 (1949). (3) C . J. Egan and R. V. Luthy, Ind. Eng. Chem., 47, 250 (1955).
(4) R. V. Luthy, U. S. Patent 2,855,444 (1958). (5) J. R. Goates, R. J. Sullivan, and J. B. Ott, J . Phys. Chem., 63, 589 (1959). (6) R . P. Rastogi and R. K. Nigam, T r a n s . Faraday Soc., 55, 2005 (1959).
V o l u m e 68, Number 0 September, 1864
2618
J. R. GOATES,J. B. OTT, N.F. MANGELSON, AND R. J. JEXSEN
tion column operating a t a reflux ratio of approximately 50: 1. Only the center third cut in each distillation was used in the measurements. Phillips research grade toluene was used without further purification. The amount of liquid soluble-solid insoluble impurity as estimated from the change in melting point with fraction melted is as follows: Tic&,0.01 mole %; benzene, 0.04 mole %; toluene, 0.04 mole %; p-xylene, 0.02 mole 70; anisole, 0.01 mole %; phenetole, 0.09 niole %; and diphenyl ether, 0.19 mole %. The problems encountered in estimating the impurity in pseudocuinene from its freezing point are described in a previous paper.? By a method similar to the one described in that paper, the purity of the pseudocumene is estimated to be >99.8 niole %. Apparatus, Tentpemture Scale, and Accuracy of Measurements. The freezing point apparatus has been described previously. Except for the TiC4-benzene system, temperatures were measured with a platinum resistance thermometer of laboratory designation T-2. T-1 was used for the TiC14-benzene system. The caIibrations of these thermometers have been previously described.', The temperature scale used is conservatively estimated to be accurate to wit>hin *O.O5"K. over the temperature range of the measurements. The calibration of the thermometers was checked periodically during the measurements; no significant changes were observable. Both time-temperature cooling and warming curves were used in constructing the phase diagrams. Agreement between the two methods was generally within 0.03'. The accuracy of the freezing points of the solutions and the invariant temperature points where stirring was possible is estimated t o be within 0.1 O. The freezing points of the pure materials are estimated to be accurate to within *O0.05"K. The values reported have been corrected to 0% impurity. 0" was talien as equal to 273.150"K.
Results Table I summarizes the freezing point data for all the systems studied. Table I1 sunimarizes the invariant teiiiperatures and compositions for the different systems. Figures 1, 2 , and 3 show the resulting phase diagrams for the three binary systems of TiC14 with benzene, anisole, and phenetole, respectively. The phase diagrams of the other systems are not reproduced since they were very similar to the benzene-Tic14 diagram. Only one eutectic and no other invariant points were observed in these systems. It is evident from the diagrams that, unlike the corresponding CCld system, of the aromatics studied only anisole and phenetole form solid compounds. I n both of these systems the The Journal of Physical Chemistry
0.0
02
M o Ie
0.4
0.6
0.a
Fr a c t i o n Tit a n lum Te t ra c h Ior Id e
Figure 1. Phase diagram for the Tickbenzene system.
solid compound consists of one T i c & niolecule to one aromatic ether molecule. The anisole and phenetole compounds melted a t 317.21 and 281-96OK., respectively. The TiCI4--anisole compound has been previously reported. Hamilton, et al.," and Cullinane, et ~ 1 . ~ ' ~ crystallized the 1: 1 conipound froin a solution of TIC], and anisole. Reference 11 reported the melting point of the compound to be 44-45' (317-318OK.); ref. 12 reported 36' (309OK.). These can be compared with the value of 317.21OK. from the present work. Reference 12 reported a complete solid-liquid phase diagram for the TiC14-C6Ho system that shows a solid (7) J. B. Ott, J. R. Goates, and A. H. Budge, J . Phys. Chem., 66, 1387 (1962). (8) J. R. Goates, J. B. Ott, and N. F. Mangelson, J . Chem. Eng. Data. in press. (9) J. It. Goates, J. B. Ott, and A. H. Budge, J . P h y s . Chem., 6 5 , 2162 (1961). (10) J. R. Goates, J. B. Ott, and N. F. Mangelson, ibid., 67, 2874 (1963). (11) P. M. Hamilton, R. McBeth, W. Bekebrede, and H. Sisler, J . Am. Chem. SOC.,75, 2881 (1953). (12) N. 41. Cullinane, S. J. Chard, and D. hl. Leyshon, J . Chem. Soc.,
4106 (1952).
INFRARED STUDIES OF TiC1,
WITH
AROMATIC HYDROCARBONS AND ETHERS
Table I : Freezing Points of Pure Compounds and Their Binary Solutions" ILlole fraction 'Ticla
Mole fraction TiCla
Freezing point, OK.
Freezing point, OK.
0,0000 0,0909 0.1748 0.2891 0.3562
TiCl4-benzene system 278.66* 0.4462 251.96 272.93 0.4977 248.52 267.96 0.5531 244.61 261.29 0.6161 240.00 257.45 0.6809 234.09
Mole fraction TiClr
Table I1 : Eutectic Temperatures and Compositions
Freezing point,
234.22 237.02 239.17 242.88 246.36 249. O l b
0,0000 0 0382 0.0654 0.2215
TiC14-toluene system 178.16* 0.3304 208.97 176.71 0.4436 217.76 175.69 0.5635 225.51 197.92 0.6737 231.74
0.7830 0.8917
237.69 243.41
0,0000 0.0544 0.1210 0.1918 0.2952 0.3980
286. 36* 284.20 281.42 278.30 273,40 268,20
TiCl,-p-xylene system 0.4505 265,25 0.5263 260.61 0.6044 255.02 01.6545 251.07 0.7060 246,29 Cl ,7408 242.64
0 . '7729 0.8030 0.8541 0.9027
239,Ol 238.26 241.20 243.95
0.0000 0.1175 0,2195 0.3127
TiCld-pseudocumene sys t'em 229,35' 0.3871 214,41 0,7137 225.17 0.4558 215.71 0.8037 221.42 0.5209 220.77 0.9057 217.65 0.6199 227.51
233 33 238 44 243 94
0,0000 0.1114 0.2246 0.3211
TiC14-diphenyl 299.98* 0,4424 295.22 0.5633 0 6826 290.32 286.13 0.7999
247 47 244 80 246 20
0.0000 0,0224 0.0488 0.1304 0.2031 0,3044
235. 9gb 273.2d 287.58 302.91 309.76 314.54
TiC14-anisole system 0.4032 316.51 0.5075 317.21 0.6060 316.61 0.7098 314.71 0.8063 311.26 0,9000 304.29
0.0000 0,0159 0.0284 0.0409 0.0993
243. 70* 243.17 242,73 242.30 259. 4d
TiCl,-phenetole system 0.2035 272.84 0.3022 278.41 0.4021 281.23 0.5085 281.95 0.6046 281.22
Eutectic temp., OK.
System
OK.
0.7059 0.7627 0.8060 0.8802 0.9486 1,0000
ether system 280.72 0.8897 275.00 0.9072 268.23 0.9406 259.18
2619
TiClpbenzene TiC14-toluene TiC14-p-xylene TiC14-pseudocumene TiCL-diphenyl ether TiCI1-anisole
233 175 237 212 244 235 248 242 247
TiC1,-phenetole a
35 01 35 71 51 90 91" 02 93"
Eutectic comoosition. mole fraction TiClr
0.688 0.083 0.787 0.420 0.909 o. 999" 0,049 0,977"
Second eutectic
320
r----
300 Y 0
0.9508 0.9802 0.9895 0.9993
296 284 276 253
10 57 3d 8$
0.6996 0.7992 0.8969 0.9797 0.9903
279 275 269 248 248
47 99 81 11 57
0" = 273.150'K. Corrected t o 0% impurity. Literature value, R. R. Dreisbach, hdvances in Chemistry Series, No. 15, American Chemical Society, Washington, D. C., 1955, Less accurate value on steep portion of the curve. p. 20.
0
0.2
0.4 Mole
0.6
0.8
I .o
Fraction T i C I ,
Figure 2. Phase diagram for the TiC14-anisole system.
and warming techniques and cooling to lorn temperatures, but found nothing to indicate that Tic& and C,H, form anything other than a simple eutectic syscompound with the empirical formula 3TiCl4.C6H6. tem. We very carefully examined this system in the neighborI n comparing Fig. 1 with the phase diagram of ref. 12, it appears that ref. 12 based their conclusions for hood of the 3 : 1 composition by means of slow cooling Volume 68, A-umber 9
September, 1964
2620
J. R. GOATES,J. B. OTT, N. F. MANGELSON, AND R. J. JENSEN
288
280
!!
2
i
‘
264
248.5
-
!i
:(q -A-d 248.0
256
247.5
0.97
0.98 099
1.0
241.6 242.4
248
pounds formed between TiC1, and p-dioxane, tetrahydropyran, and tetrahydrofuran. Rolsten and Sisler’s13infrared study of p-dioxane-TiBr4 shows that the bonding in this system is between the ether oxygen and the titanium atom. Sumarokova, et aZ.,l4reached the same conclusion for the p-dioxane-TiC14 system. We have used infrared absorption measurements to investigate the bonding in the TiC14-anisole compound. This system was convenient to study because the solid melts very near room temperature and infrared spectra could be obtained on the solid compound as well as liquid solutions. Absorption spectra were obtained with a Beckman I R 3 spectrophotometer for the pure components, the solid complex, and eight liquid mixtures ranging in composition from 10 to 90 mole yoTiC14. We were particularly interested in distinguishing between (a) bonding through the oxygen and (b) bonding through the aromatic ring. Three observations are pertinent. (1) The symmetrical aromatic-C-0 stretch at 1172 cm.-’ in anisole disappears in the compound. This is analogous to Rolsten and Sisler’s observation for the C-0-C stretch in the TiBr4-dioxane system.13 (2) The out-of-plane bending (aromatic ring) four-band pattern in the 16002000 cm.-l region of anisole assumes the pattern characteristic of 1,2,3-trisubstitution in the complex. (3) In-plane ring breathing frequencies of anisole are not significantly changed in the compound. Infrared spectra were also obtained in a T i C k p xylene solution (mole fraction of TiC14 0.87) and a TiCld-diphenyl ether solution (mole fraction of TiCb 0.97). These spectra were compared with the spectra of pure p-xylene and diphenyl ether, respectively. NO significant changes were evident in the region from 600 to 4000 cm.-l in either system. These observations are all consistent with a model in which the anisole and phenetole involve bonding a t the site of the oxygen rather than through the aromatic ring. It seems probable, therefore, that the bonding in these compounds is similar to that which was proposed for the TiBrr and TiCGdioxane system^.'^,^^ It is interesting to note that of the three ethers studied only diphenyl ether, the ether for which steric effects around the oxygen are the greatest and the electron donating power of the oxygen is the smallest, fails to form a solid compound. Although only anisole and phenetole form solid phase compounds, interactions are evident in all the liquid
0.0 0 . 0 2 *
0.04 P
240
0
(
i
A
0.2
a
0.4
0.6
0.8
I .o
M o l e Fraction T i C l 4
Figure 3. Phase diagram for the TiCld-phenetole system.
compound formation on only two points of their diagram. If these points are in error, there is no evidence for the existence of the compound. Excluding the two points in question, the general shape of the diagram in ref. 12 is similar to Fig. 1. Of greater significance, only a single eutectic temperature was obtained in both ref. 12 and the present study over the entire range of composition. Infrared Spectroscopic Studv. Because each of the aromatic substances that is known to form the cc14 addition compound is characterized by a high electron density in the benzene ring, it has been suggested that the aromatic ring acts as a donor in a charge-transfer process in the CC14 systenm5 The type of bonding in the two TiC14systems reported, however, appears to be different. The relatively very high melting points of the TiClpether compounds suggest a different type of bonding than that present in the CC14systems. Several aliphatic ethers are known to form solid addition compounds with TiC14. For example, Hamilton, et al., l 1 reported high melting point addition comT h e Journal of Physical Chemistry
(13) R. Rolsten and H. H. Sisler, J . Am. Chem. Soc., 7 9 , 1819 (1957). (14) T. Sumarokova, Yu. Nevskaya, and E. Yarmukhamedova, Zh. Obshch. Khim., 30, 1705 (1960).
2621
THEIODINE COMPLEXES OF FLUOROBENZEXES AND FLUOROTOLUENES
solutions. All the TiC14-aromatic solutions studieid have a red color with the exception of the orange-coloreid TiC14-CsH, solutions. Furthermore, the color deepens as the electron density of the aromatic ring is increased. We are currently investigating the thermodynamic properties of these liquid complexes.
Acknowledgment. The authors gratefully aclinowledge the support given this project by the Office of Army Research (Durham). We also thank Mr. Arnold Loveridge for his assistance with the freezing point measurements and Dr. R. T. Hawkins for help in the interpretation of the infrared spectra.
The Iodine Complexes of Fluorobenzeries and Fluorotoluenesl
by Milton Tamres Department of Chemistry, University o,f Michigan, Ann Arbor, Michigan
(Received A p r i l 18, 1964)
-
The charge-transfer (c.t.) bands of a series of iodine complexes with mono-, di-, and trifluorobenzene (in CC1, and in n-heptane) and fluorotoluenes (in n-heptane) were studied. The c.t. bands appear in a region where the free donors also absorb. For those cases where the band maximum was not observed, it was estimated by extrapolation of the absorption curve. The effect of fluorine substitution is to decrease the equilibrium constant for iodine complexation, in correlation with Taft u* values. In most cases, there is an increase in the molar absorbancy index a t the band maximum. There is obsermd also an apparent blue shift of the c.t. band which is in a direction opposite to that expected from the ionization potentiah of the donor molecules. This may be due to the superposition of two c.t. bands which arise from the removal of the degeneracy of the highest occupied orbitals in benzene on substitution. A temperature dependence study of the fluorobenzene-iodine complex both in n-heptane and in CCI, gave a value of -1.4 kcal. mole-1 for the heat of reaction.
Introduction Previous studies on polymethylbenzene-iodine coniplexes213have shown that increased methyl substitution (a) increases the stability of the complex, (b) gives a red shift of the charge-transfer (c.t.) band, and (c) decrerises the molar absorbancy index of the complex (a,) a t the wave length of maximuni absorption (Amax). These observations, except for the last, are consistent with the inductive property of the methyl group and its effect of systematically lowering the ionization potential (I,) of the donor molecule on continued substtitution. The opposite trend in a, (reported also for olefin-iodine complexes4) has been explained as being due to the existence of several geometric arrangements
of the complex, each with its individual equilibrium constant ( K ) and a,, which could lead to a nonlinear log K vs. 1/T plot.6 Since multiple forins are more likely to be present in weak rather than strong complexes, because the latter would favor the existence of a single, stable structure, the fluorobenzenes would seem to be a favorable system to study this aspect. (1) Presented before the Division o f Physical Chemistry at the 146th National Meeting of the American Chemical Society, Denver, Colo., Jan., 1964. (2) (a) H. Benesi and J. H. Hildebrand, J . Am. Chem. Soc., 71, 2703 (1949); (b) L. J. Andrew and R. M. Keefer, ibid., 74, 4500 (1952). (3) M . Tamres, D. R. Virzi, and S.Searles, ibid., 75, 4358 (1953). (4) J. G. Traynham and J. R. Olechewski, ibid., 81, 571 (1959). (5) L. E. Orgel and R. S.Milliken, ibid., 79,4839 (1957).
V o l u m e 68, Number 9 September, 2964
