M. Okazaki, I. Hara, and T. Fujiyama
1586 f1.96X (2/&) X 4.98% = f11.3%. In the caseof ro. however, the limits of relative error can be theoretically reduced further to k1.96 X (l/&) X 4.98% = 5.64% as follows. Since ro is generally small
where the asterisk means extrapolated value to t = 0. Assuming the exchanging curve near t = 0 to be linear, the coefficient of variance of A,*, a,*lps‘, can be readily derived from statistical theory concerning the regression in the case where Cs(= us/@,) is constant. That Is
where ti is the exchanging time of the ith time of the fih sampling n Is the number of samplings, and Tis the average of ti. If @,p near t = 0 is assumed approximately equal to @s*2, this equation is reduced to
where V(t1) is a function of t,’s in the form of variance. When nand V(t,) are taken large enough near t = 0, us*/@,* converges to zero. However practically us*/@,* was taken about 2CJ3 in the present work. Therefore, ur*/wLr* was nearly equal to C., (34)The 95% confidence limits of the expected values of 6’s were calculated from the variances of the data shown in Figures 4 and 7 by using the tdistribution table. The comparatively wide confidence limits are due to the relatively narrow ranges of Sand due to the small number of samplings.
Spectroscopic Studies of Surfactant Solubility. 2. Solubilization in Carbon Tetrachloride by Complex Formation with Chloroform Mitsuyo Okazaki, lchlro Hara, Laboratory of Chemistry, The Department of General Education. Tokyo Medical and Dental University, Ichikawa, Japan
and Tsunetake Fuliyama” Department of Chemistry, Faculty of Science, Tokyo Metropolitan University, Setagaya, Tokyo, Japan (Received December 3, 1975) Publication costs assisted by The Department of General Education
Infrared spectra of water soluble surfactants were studied with respect to their solubility in carbon tetrachloride. The ternary solution of carbon tetrachloride-chloroform-surfactant showed by quantitative analysis of the C-D stretching vibration bands of chloroform-d that the surfactants dissolved in these solvents by forming a complex conaisting of several chloroform molecules to one surfactant molecule. The number of chloroform molecules which form a complex with a surfactant decreases as the mole ratio of carbon tetrachloride to chloroform increases. A t the mole ratio corresponding to the solubilization limit, a (1:l)complex of chloroform and surfactant is formed. The surfactants studied are dodecyldimethylamine oxide and cetyltrimethylammonium chloride. Pyridine is also studied as a reference system.
Introduction
Experimental Section
In a previous publication, the infrared spectra of some water soluble surfactants have been reported. From quantitative analysis of the absorption intensity, it had been shown that molecules that dissolve in chloroform form a complex with several solvent chloroform molecules. The bonding between a surfactant and solvent chloroform had been shown to be of hydrogen bond type.l The present study concerns itself with a further study of solubilities of some surfactants in chloroform by the use of infrared spectra. The surfactants being studied are widely known to be insoluble in carbon tetrachloride, but can be made soluble in carbon tetrachloride by adding a small amount of chloroform. Focusing our attention on the infrared absorption band of chloroform-d, the effect on dilution with carbon tetrachloride on the hydrogen bonding between surfactants and chloroform can be seen. The surfactants studied were dodecyldimethylamine oxide (C12AO) and cetyltrimethylammonium chloride (CTAC1). Many spectroscopic studies on ternary solutions have been performed and are well documented in the literatures.2-22
Materials. Chloroform-d was purchased from Merck and Co., Ltd. and used without further purification. Carbon tetrachloride was purchased from Tokyo Kasei Co., Ltd. and used after distillation. An aqueous solution of dodecydimethylamine oxide was supplied from Kao Atras Co., Ltd. and was used after recrystallization from acetone. Cetyltrimethylammonium chloride was purchased from Tokyo Kasei Co., Ltd. and purified by recrystallization from acetone. The purities of these samples were checked by thin layer chromatography. Pyridine was purchased from Tokyo Kasei Co., Ltd. and was used without further purification. Infrared Absorption Measurements. The absorption spectra were obtained from a JASCO IR-G grating spectrometer with a resolution of 1 cm-l. KBr cells of various thicknesses 0.1,0.5,1.0, and 2.0 mm were used to obtain the spectra of the ternary solutions of chloroform-d-carbon tetrachloride with a surfactant at various concentrations. The thickness of the sample cells were determined by the interference fringe method.
The Journal of Physical Chemistry, Vol. 80, No. 14, 1976
1587
Spectroscopic Studies of Surfactant Solubility carbon t e t r a c h l o r i d e
chloroforrn-d412AOcarbon t e t r a c h l o r i d e
3000
4000
1600 1200 wavenumber ( cm-1 )
2000
400
800
Figure1. Infrared spectra for binary (chloroform-d-carbon tetrachloride) and ternary (chloroform-d-CI2AO-carbon tetrachloride) solutions.
0.05
Bonded (
0.04
rnole/l )
. % lJ .d
a
0.03
‘c1 rl
0
.VI
g
0.02
0
0.01
2400
2300
2200 wavenumber ( c m - 1 )
2100
2000
Figure 2. Concentration dependence of the C-D stretching vibration of chloroform-d for ternary solution (chloroform-6CI2AO-carbon tetrachloride). @CC14/@CDC13= 36.6.The numerical values on the peaks show molar concentration of C12AO.
Ternary solutions containing varying concentrations of solute in the solvents were prepared before measurement by weighing the surfactant and solvents in the sample flask. Since the solutes are very hygroscopic, they were dried thoroughly to an anhydrous condition before each measurement. The
elimination of water from the sample solution was confirmed by observing the infrared spectra in the region of 4000-2000 cm-l. The refractive index, r z ~ ~ and O , the specific gravity of the solution were measured with an Abbe refractometer and a The Journal of Physical Chemistry, Vol. 80, No. 14, 1976
M. Okazaki, I. Hara, and T. Fujiyama
1588
TABLE I: Relative Intensities of the C-D Stretching Vibration and Calculation of the Solvation Number, n,for the Chloroform- d-OlzAO-Carbon Tetrachloride System
0
0.97
3.62
0.017 0.065 0.090 0.114 0.182 0.182 0.329 0.405 0.538
1.4470 1.4471 1.4472 1.4473 1.4474 1.4476 1.4476 1.4481 1.4484 1.4488
1.48 1.478 1.472 1.469 1.465 1.457 1.457 1.438 1.428 1.411
0 0.050 0.100 0.200 0.400 0.800
1.4540 1.4542 1.4545 1.4547 1.4550 1.4560
1.529 1.520 1.513 1.497 1.465 1.401
0
1.4571 1.4572 1.4573 1.4573 1.4574 1.4580
1.554 1.551 1.548 1.544 1.539 1.535
1.4590 1.4594 1.4594 1.4595 1.4596 1.4598
1.567 1.565 1.562 1.559 1.553 1.550
1.4603 1.4604 1.4604 1.4603 1.4602 1.4602 1.4603
1.568 1.566 1.566 1.563 1.561 1.557 1.550
0
0.018 0.035 0.058 0.090 0.111
11.09
0
0.0172 0.0311 0.0471 0.0848 0.1004 36.60
0
0.0094 0.0138 0.0314 0.0439 0.0647 0.1054
0
0.186 0.629 0.886 1.064 1.709 1.647 2.943 3.610 5.029 0
0.438 0.935 1.686 3.359 6.595 0 0.118
0.234 0.371 0.584 0.707 0
0.089 0.159 0.249 0.450 0.522 0
0.0282 0.0458 0.0977 0.1321 0.1965 0.2991
1.302 1.279 1.262 1.252 1.216 1.209 1.189 1.120 1.068 1.010 0.484 0.459 0.448 0.417 0.359 0.266 0.171 0.167 0.164 0.158 0.151 0.148 0.0565 0.0542 0.0521 0.0504 0.0460 0.0435 0.0161 0.0155 0.0153 0.0142 0.0138 0.0130 0.0110
picnometer, respectively, a t the same time as the absorption measurements. All the measurements were taken at 20 f 2 OC and the absorption spectra of the C-D stretching vibrations in the frequency region of 2500-2000 cm-l were measured carefully with a resolution of 1 cm-l and scanning speed of 33.3 cm-l min-l. The absorption due to carbon tetrachloride was eliminated by use of a variable pathlength cell in the reference side. The thickness of the variable cell was adjusted so that the absorption band of carbon tetrachloride in the region of 2350-2250 cm-l was completely eliminated.
Results and Discussion Infrared Spectra and Intensity Analysis. In Figure 1the infrared spectra for a binary solution of CCl4-CDCl3 and for a ternary solution of CCld-CDC13-C12AO are shown. It is seen from the figure that the infrared spectra originating from CDCl3 show remarkable changes in the fundamental bands of chloroform-d; the C-D stretching (v(C-D)), the C-D bending (S(C-D)), and the C-C13 symmetric stretching (v(C-Cl)) vibrations. As is discussed in a previous report,l these are certainly due to hydrogen bond formation between CDCl3 and C12AO. In the case of the spectra in Figure 1, the frequency shifts of these fundamental bands due to hydrogen The Journal of Physical Chemlstry, Vol, 80, No. 14, 1976
0
0.107 0.358 0.501 0.599 0.946 0.912 1.569 1.886 2.534
6.29 5.51 5.57 5.25 5.20 5.01 4.77 4.66 4.71
79 79 79.5 80 80.5 80.5 81.5 82 82.5
69 69 68 68 67 68 67.5 68 68
3.94 4.19 3.66 3.43 3.00
79.5 80 82.5 85
67 67 66 67 68
2.89 2.91 2.79 2.80 2.74
80
0
0.197 0.419 0.731 1.373 2.398
88
0
0.052 0.102 0.162 0.252 0.304
81 82
82.5 83.5
62 62 62 63 63.5
0
0.033 0.060 0.092 0.165 0.191
1.92 1.93 1.95 1.95 1.90
84 84.5 85 87.5 88
64 64 64 65 66
0.87 0.96 0.90 0.87 0.88 0.83
85.5 85.5 88.5 90 94 94.5
72 71 71 71 71 71
0
0.0082 0.0133 0.0283 0.0383 0.0569 0.0871
bonding are observed to be -84, +28, and -16 cm-l, respectively. The absorption spectra for the ternary solution of CC14-CDC1&12AO in the frequency region from 2400 to 2000 cm-l are shown in Figure 2. The bands of the C-D stretching vibration corresponding to the free and the bonded states are observed separately. As the concentration of C12AO increases, the intensity of the bonded band increases remarkably, while that of the free band decreases. The procedure for the intensity measurements of v(C-D) for ternary solution of CC14-CDC13-surfactant is the following. We first make a binary mixture of CCl4-CDC13, the molecular concentrations of which are Cocci, and C°CDC13. The ratio, C o c c ~ / C o c ~ is c ~called s , a dilution ratio hereafter. For a binary solution of a given dilution ratio, we observed the intensity change of v(C-D) by dissolving various amounts of surfactant. We repeat these procedures for various dilution ratios. The molar concentrations of the resultant ternary mixture, CCDCi3, CcC14,and C,, are determined from the observed weight concentration and the density of the solution. The definition of intensities are retained as those described in the previous rep0rt.l The relative intensity, I , of an absorption band is defined as
I =
1
band
In (Io/I)d In (v)
(1)
Spectroscopic Studies of Surfactant Solubility
1589
TABLE 11: Relative Intensities of the C-D Stretching Vibration and Calculation of the Solvation Number, n,for the Chloroform- d-CTAC1-Carbon Tetrachloride System
coca4/ COCDCln
103cCT, mol/cm3
0
d
cm-l
cm-l
103cb, mol/cm3
n
1.4470 1.4480 1.4489 1.4493 1.4499 1.4507 1.4514 1.4529
1.48 1.465 1.463 1.458 1.453 1.446 1.431 1.416
0 0.428 0.810 1.070 1.331 1.594 2.475 3.126
1.311 1.278 1.269 1.255 1.234 1.223 1.169 1.141
0 0.218' 0.406 0.530 0.654 0.772 1.160 1.421
4.54 4.23 4.17 4.17 3.96 4.10 3.88
56 57 57 57.5 58 58 58.5
42.5 42 42 42.5 42.5 42 42.5
1.536 1.529 1.517 1.499 1.482 1.486
0
0.159 0.283 0.379
1.4550 1.4553 1.4560 1.4567 1.4570 1.4574
0.200 0.622 1.222 2.018 2.590
0.386 0.373 0.369 0.356 0.318 0.281
2.56 2.61 3.18 2.85 2.25
62 61.5 64 64 65
41 42 41.5 41.5 41
0 0.021 0.026 0.051 0.099 0.101 0.195 0.283
1.4577 1.4578 1.4578 1.4579 1.4580 1.4583 1.4584 1.4590
1.555 1.549 1.550 1.545 1.540 1.535 1.517 1.499
0 0.089 0.151 0.280 0.451 0.533 0.904 1.451
0.179 0.176 0.170 0.171 0.164 0.161 0.157 0.137
1.71 2.31 2.18 1.78 2.06 1.74 1.85
63 64 65 65 66 66 67
41 40 41 41 41 41 40.5
0
1.4591 1.4591 1.4591 1.4593 1.4592
1.565 1.563 1.562 1.560 1.560
0
0.0769 0.0760 0.0758 0.0746 0.0748
1.20 1.25 1.20 1.25
66 67 67 67
41 41
Ib*,
0
0.048 0.096 0.127 0.157 0.195 0.283 0.366 1.25
0
0.034 0.101
3.33
7.49
- vo), cm-l
nD
0.010 0.016 0.025 0.028
If*,
0.033 0.053 0.080 0.095
-(u
b 2 ,
cm-l
0
0.087 0.264 0.505
0.807 0.856 0
0.036 0.060 0.111 0.176 0.208 0.340 0.523 0
0.012 0.020 0.030 0.035
40
40
CDC13, respectively. Then the absolute intensities of the u(C-D) band for the bonded and free CDCls are, respectively 0.1054
0.3
\
in the unit of cm2/mol. In order to determine both rfand r b simultaneously, we define a new form of a relative intensity, I* I* = fafcI (4)
0.2 d
0 E
I
The factor, fd, corresponds to the correction factor for the local field effect23
H
0.1
where nD is the refractive index of the solution. The factor, is introduced so that the relative intensity, I , can be compared at the same molar concentration for a given dilution ratio. Thus
fc, 0
0.011
0.012
0.013
0.014
If*( cm-1
0.015
0.016
)
Fiaure 3. h,* - k" 1)lot at C'CC~4 / @ ~ ~ ~ 1 =3 36.6 fora ternary solution (chloroform-d-C1~AO-carbontetrachloride). Numerical values on the circles show the molar concentration Cj2A0.
in the unit of cm-l, where 1 is a thickness of sample, I o the energy of incident light, I the energy of transmitted light, and u the frequency of light. The molar concentration of CDCl3 is expressed as (2) CCDC13 = cf + Cb where Cf and Cb are molar concentrations of free and bonded
fc
= C°CDC13/CCDC13
(6)
together with the relations
cf*= f c c f Cb* = f c C b cf*+ c b * = COCDCl,
(7)
Typical examples of the observed results are summarized in Table I for &A0 and in Table I1for CTACl. From Eq 3 and 7 , the relation
The Journal of Physical Chemistry, Vol. 80, No. 14, 1976
1590
M. Okazaki, I. Hara, and T. Fujiyama
TABLE 111:Final Results of the Intensity Data for the Chloroform-d-ClaAO-Carbon Tetrachloride System (A) and the Chloroform-d-CTAC1-CarbonTetrachloride System (B)
A 0 0.97 3.62 11.09 36.60
12.30 5.66 2.296 0.858 0.273
106 86 75 66 59
12.30 4.92 2.46 1.23
107 78 73 63
1726 2191 2268 2666 3422
16.3 25.6 30.4 40.4 58
5.2 3.6 2.8 1.9 0.9
1930 2262 2482 2709
18 29 34 43
4.2 2.7 2.0
85
92 85 77 52
B 0
1.25 3.33 7.49
1.2
77 78 68 52
TABLE IV: Results of the Intensity Data for the Chloroform-d-Pyridine-CarbonTetrachloride System C0cc4/ COCDCl? 0
4.15
rf,
103coCDC13, mol/cm3
cm2/mol
cm2/mol
12.30 2.049
107 66-
1780 1175
rb,
0.8
rb/rf
-(v
- vo),
Avlla,
cm-l
cm-I
30.5 30
40.5 35
16.6 17.8
0
Table 111. From the trend in Table I11 it can be seen that I'f decreases in magnitude as the dilution ratio increases. This corresponds to the fact that the hydrogen bonding between solvent CDC13 is broken as the concentration of CC14increases. Therefore, even in the ternary solution of CC14-CDC1~-surfactant, most of the CDC13 molecules are dissolved in CCld when the dilution ratio is large. On the other hand, r b increases in magnitude as the dilution ratio increases. This probably corresponds to the fact that the strength of hydrogen bond between CDCl3 and a surfactant increases as the dilution ratio increases. The frequency shift of the u(C-D) due to hydrogen bond formation increases as the dilution ratio increases (see Tables I and 11),which is consistent with the increase of
B
rb.
I
I
B
I
I I
0.6
t v
E
.4.y E
0.4
8
Determination of Solvation Number. Figure 4 shows the observed temperature dependency of the solubility of C12AO and CTACl in CC14. At room temperature, both Cl2AO and CTACl are hardly soluble in CC14.2s Therefore, the solvation number, n , can be determined exactly by method described previously.Using the observed r b value, c b is determined as
0.2
c b 20
40
temperature
= fdIb/rb
(9)
60 (
O C
)
Flgure 4. Solubilities of CI2AO (0) and CTACl ( 0 )in carbon tetrachloride.
is obtained, which indicates that both rf and r b are obtained simultaneously for a given dilution ratio, when a plot of I b * against If* for a series of concentration of a surfactant is made.24*25 In Figure 3, a typical example of a I b * - If*plot for a ternary solution of CCLp-CDC13-C12AO at (C 0 c c 1 4 / C o c ~ c l 3 ) = 36.6 is shown. It is evident from the figure that a linear relationship is obtained between I b * and If*. Consequently, rf and r b do not change their magnitude in this concentration range and at this dilution ratio. Linear behavior was obtained for all the systems studied in the present study. The rf and r b values thus obtained are summarized in The Journal of Physical Chemistry, Vol. 80, No. 14, 1976
and the solvation number is determined as
n = cb/c,
(10)
In Tables I and 11,the c b and n values calculated from eq 9 and 10 are summarized. The tables show that almost constant n values are obtained for a given dilution ratio and that the n value changes in magnitude as the dilution ratio changes. As the n value correspond to the number of chloroform-d molecules which forms a complex with one surfactant molecule, the above results indicate that the structure and nature of a complex of CDCl3-surfactant are strongly related to the dilution ratio. The averaged n values, a, a t various dilution ratio are summarized in Table 111for both CnAO and CTACl systems. Spectroscopic Information and Solubilization. The intensity data of the preceding sections show that a complex consisting of several CDCl3 molecules and one surfactant is
Spectroscopic Studies of Surfactant Solubility formed in the ternary solution of CCL-CDC13-C12A0 and of CCl4-CDC13-CTACl. It is important to emphasize that the solvation number, n, decreases in magnitude as the dilution ratio increases for both C12AO and CTACl systems. The n value approaches unity almost as the dilution ratio approaches the solubilization limit. This suggests that the surfactants can dissolve in CC14 only when they form complexes with CDC13 molecules. In the case of C12A0, for example, a complex is formed with about five CDC13 molecules for a binary mixture of CDC13-C12AO. On adding CCl4 to the binary solution, almost all CDC13 molecules are dissolved in the CCl4. Moreover, the CDCl3 molecules which formed a complex with the CIAO molecule are taken from the complex one by one, until there is no CDC13 molecule which can make a complex with the Cl2AO molecule. This may be the microscopic situation corresponding to the precipitation of C12AO from the ternary solution. Table I11 shows that the absolute intensity of hydrogen ,bonded CDC13, r b , increases as the dilution ratio, Cocci4/ C0CDCl3, increases. On the other hand, the number of CDC13 molecule decreases with the increase of the dilution ratio. If the strength of a hydrogen bond can be represented by the intensity ratio, Ij,/Ff, the product of the intensity ratio and the solvation number, n, is an appropriate estimate of the stabilization energy of one surfactant molecule through hydrogen bond formation in the solution. The last column of Table I11 shows the calculated R(Ij,/I’f) products. The result indicates that the product takes roughly the same value for all dilution ratios. This may correspond to the fact that the stabilization energy necessary for the surfactants to be dissolved is almost the same for all the dilution ratios. The decrease of the number of hydrogen bonding CDCl3 is properly compensated by the increase of the strength of the remaining hydrogen bonds. If we give a little too much meaning to the h(I’b/I’f) value, its gradual decrease in magnitude with the increase of dilution ratio would be attributed either to the increase of an entropy term or to the decrease of intermolecular interactions between complexes, although we are not certain of the existence of such interactions yet. This certainly suggests future work into the problem.
Supplementary Results and Discussion. In the previous report,l the binary solution of pyridine and CDC13 was discussed as a reference system, because pyridine is known to form a (1:l)complex with CDC13. The results of the present study for the ternary solution of CC14-CDCla-pyridine are
1591
summarized in Table IV. For this system, the observed values for r b and Av(C-D) are constant on passing from the binary solution to ternary solution. This corresponds to the fact that the strength of the hydrogen bond between chloroform and pyridine does not change by dilution with CC14. Because pyridine is soluble in CC14, a complex such as this dissociates into pyridine and chloroform on dilution with CC14.Therefore, it is not necessary to form a different type of hydrogen bond on dilution in order to be stabilized in the ternary solution. Incidentally, it is of no meaning to calculate the solvation number, n, using eq 10 for the ternary solution of pyridine, although a (1:l)complex between chloroform and pyridine is formed even in the ternary solution. Acknowledgment. The authors are pleased to express their sincere thanks to all the members of Fujiyama Laboratory and Tokyo Metropolitan University for their stimulating and helpful discussions. Helpful discussions and encouragement from Miss Yumiko Katayanagi are also deeply appreciated.
References and Notes (1) M. Okazaki, I. Hara, and T. Fujiyama, J. Phys. Chem., 80, 64 (1976). (2)C. J. Creswell and A. L. Allred, J. Am. Chem. SOC.,85, 1723 (1963). (3) Soon Ng, Spectrochim. Acta, Part A, 28, 321 (1972). (4) T. Gramstad and 0. Vikane. Spectrochim. Acta, Part A, 28, 2131 (1972). (5) K. B. Whetsel and R. E. Kagarise, Spectrochim. Acta, 18, 329 (1962). (6)K. B. Whetsel and J. H. Lady, J. Phys. Chem., 68, 1010 (1964). (7) B. €3. Howard, C. F. Jumper, and M. T. Emerson, J. Mol. Spectrosc., IO, 117 (1963). (8) M. L. Josien, J. P. Leicknam, and N. Fuson, Bull. SOC.Chim. Fr., 188(1958). (9) R. D. Green and J. S. Martin, J. Am. Chem. SOC., 90, 3659 (1968). (IO) A. Allerhand and P. R. Schleyer, J. Am. Chem. SOC., 85, 1233 (1963). (11) G. R. Wiley and S. L. Miller, J. Am. Chem. SOC., 94, 3287 (1972). (12)F. L. Sleiko, R. S. Drago, andD. G. Brown, J. Am. Chem. Soc., 94, 9210
(1972). (13)A. Allerhand and P. v. R. Schleyer. J. Am. Chem. Soc., 85, 1715 (1963). (14)R. E. Kagarise, Specfrochim. Act8, 19, 629 (1963). (15) V. A. Gushchin, Opt. Spektrosk., 17, 385 (1964). (16)K. Kurosaki, Nippon KagakuZasshi, 83, 655 (1962). (17)G. S.Denisov, Opt. Spektrosk., 6, 426 (1964). (18) M. F. Pushlenkov and E. V. Komarov, Radiokhimiya, 6, 426 (1964). (19)J. T. Bilmer and H. F. Shurvell, J. Phys. Chem., 77, 2085 (1973). (20) V. F. Bystriv, V. P. Lezina, and S.M. Shostakovskii, Opt. Spektrosk., 3,339 (1967). (21)S.Nishimura, C. H. Ke, and N. C. Li, J. Phys. Chem., 72, 1297 (1968). (22)0.Torbjoern, Acta Chem. Scand., 24, 3081 (1970). (23)S.R. Polo and M. K. Wilson, J. Chem. Phys., 23,2376(1955);A. C. Gilby. J. Burr, and B. Crawford. Jr., J. Phys. Chem., 70, 1520 (1966);T. Fujiyama. J. Herrin, and B. L. Crawford, Jr., Appl. Spectrosc., 24, 9 (1970). (24)T. Fujiyama and M. Kakimoto, Bull. Chem. SOC.Jpn., in press. (25)K. 0. Hartman, G. L. Carlson, W. G. Fately, and R. E.Witowski, Spectrochim. Acta, PartA, 24, 157 (1968). (26) The results in Figure 4 were observed in the present study. The references to previous work are: C. W. Hoerr and H. J. Harwood, J. Am. Chem. Soc., 74, 4290 (1952);R. A. Reck, H. J. Harwood, and A. W. Ralston, J. Org. Chem., 12, 517 (1947);S. H. Shapiro, “Fatty Acids and Their Industrial Applications”, New York, N.Y., pp 109-1 19.
The Journal of Physical Chemistry, Vol. 80, No. 14, 1976
