NOTES
1595
According to eq 4, a plot of (J
+ (J)~+=o]}/flA+
- [(J)AP-o
against A+ should yield a straight line when AP is kept constant. Similarly, when the same quantity is plotted against A P keeping Ad constant, a straight line should be obtained. This is confirmed in Figures 1 and 2 showing thereby that eq 4 satisfies the experimental data. The phenomenological coefficients were estimated as follows. Ll1 was estimated from the solvodynamic data. Llz and Llzzwere estimated from the analysis of electroosmotic velocity data. L1122 and Llllz were estimated in a similar manner using Figures 1 and 2. The intercept in Figure 2 is equal to L112/!P $L1122/TaA4 and that in Figure 1 i s equal to Lllz/T2 &lllz/Ta~P. LIE could therefore be obtained from either of the intercepts. These values are found to agree within &4%. The values of phenomenological Coefficients obtained are
+ +
Ln/T = 3.87 X lo-' cm5sec-l dyn-l L1z/T = 1.58 X
cma sec-1 V-'
L122/T2 = 2.76 X lo-* cmasec-l L11z/T2 = -6.88 X 10-lO cm5sec-l dyn-1 V-1 Llllz/TS = 19 X 10-l6 cm7sec-l d y r 2 V-I L1122/T9 =
- 13.6 X
The validity of eq 4 was independently checked by analyzing the data on electroosmotic pressure. Electroosmotic pressure can be computed in the steady state for various magnitudes of A+ by substituting the values of phenomenological coefficients in eq 4 and using the condition J = 0. The calculated values of electroosmotic pressure using eq 4 and retaining terms up to second and third order are compared with the experimentally obtained values of electroosmotic pressure in Figure 3. The experimental and theoretical O ~ ~ P V Q B agree when terms up to third order are included. The measurements of (J)AP,o,(J)A+o, and J are fairly precise and reproducible. The departures from mean values never exceed 1% when each observation is repeated at least four times. The uncertainty in electroosmotic pressure measurements is of the order Z from of &2%. Since the mean value of L ~ I obtained Figures 1 and 2 has been used, the computed values of electroosmotic pressure may have an uncertainty of &5%. In view of these limitations, the agreement between calculated and experimental values of electroosmotic pressure may be considered very satisfactory. The above analysis, therefore, confirms that phenomenological eq 4 holds good in the nonlinear region under study.
Acknowledgment. S. N. S. is thankful to Council of Scientific and Industrial Research (India) for the award of a junior research fellowship.
10-la cm5sec-1 dyn-I V-2
For the evaluation of slopes and intercepts the method of least squares was used. Reduction of Quinone in Its Charge-Transfer Complex with the Hydrogen Molecule by Motoyuki Tsuda, Hiroo Inokuchi, and Hideo Suzuki The Institute for Solid State Physics, The University of Tokyo, and the Department of Physics, School of Science and Engineering, Waseda U n h m i t y , Toxyo, Japan (Received October I , 1 9 6 8 )
Quinone-type compounds have been extensively studied for their importance in biological functiom mainly because of their ability to form charge-transfer complexes and their capability for reversible reduction to the hydroquinone form. For example, Tollin and Green demonstrated the occurrence of light-induced electron-transfer reactions between electrically excited chlorophyll molecules and various quinones and detected a semiquinone radical intermediate by the esr method.' Further, Yamazaki and Ohnishi reporte that semiquinone plays an important role in the
4$ (VQUS)
Figure 3. Examination of the validity of eq 4: 0,experimental curve; 0,calculated curve using eq 4 and retaining second-order , calculated curve using eq 4 ~
(1) 0. Tollin and G . 66, 308 (1963).
Green, Biochim. Biophys. Acta,
6 0 , 624 (1962)
~
Volume 75,Number 6 M a y 1060
NOTES
1596
oxidation-reduction equilibrium between ferro- and ferricytochrome c or quinone and hydroquinone.2 Is it possible to find a similar reaction between quinone and hydroquinone in solid state? As we have already reportedjs molecular hydrogen adsorbs dissociatively on a surface of a solid alkali metal-aromatic complex. In this paper, we show that hydrogen adsorbed on a quinone-sodium complex in the solid phase reduces the quinone to the hydroquinone. The p-benzoquinone-sodium complex was used in this study and was prepared as follows. Sodium metal was deposited onto the surface of a quartz plate in vacuo and then p-benzoquinone, which was purified with repeated recrystallizations and sublimations, was brought into contact with the sodium film by means of vacuum sublimation. Further, the dark green complex film between p-benzoquinone and sodium was subjected to heat treatment a t 353'K for 24 hr and was evacuated completely to remove excess quinone. The purified hydrogen gas was admitted into the vessel containing the p-benzoquinone-sodium complex up to a pressure of about 100 Torr (at room temperature). When the vessel was maintained a t 353'K overnight, white crystals were isolated from the complex. The white crystals, dissolved in alcohol solution, were identified clearly as p-hydroquinone from its absorption spectra in the ultraviolet region. This reaction may be illustrated as absorb
2H2
I 2Na -+
2Na*
over
complex
+
2[Ht][H']
111
Q
-1 . . . . . . . I " -
I
200
1
JOO
t
1
eco w a w m mp
,400
I
a00
mm
.
mo
Figure 1. The absorption spectra of the p-benzoquinone-sodium complexes.
white crystals, identified as p-hydroquinone, were isolated as described above. The spectrum of a p-hydroquinone solid film is also drawn in Figure 1 as curve 1.
Acknowledgment. We gratefully acknowledge an important suggestion with Dr. Y. Harada and express our thanks to the Kawakami Foundation for financial support. (2) I. Yamazaki and T. Ohnishi, Biochim. Biophys. Acta, 112, 469 (1966). (3) T. Kondow, H. Inokuchi, and N. Wakayama, J . Chem. Phys., 4 3 , 3766 (1965);H.Inokuchi, N. Wakayama, T. Knodow, and Y . Mori, ibid., 46, 837 (1967). (4) N. K. Bridge and G. Porter, Proc. Roy. SOC.(London), A244, 259,276 (1958). ( 6 ) J. H. Baxendale and H . R . Hardy, Trans. Faraday Soc., 49, 1433 (1953). (6) Y. Harada and H. Inokuchi, Mol. Phys., 8 , 265 (1964).
2e
Step 1 is postulated to be the addition of electrons from alkali metal to the quinone producing the corresponding dianion radical 11. The addition of the hydrogen is assumed to be a secondary process forming the hydroquinone, The role of H- in reaction 2 is not clear. The observation of the spectra in the reaction processes in the solid phase supports these hypotheses. Curve 2 in Figure 1 shows the absorption spectrum of the p-benzoquinone-sodium complex in solid film; the peaks assigned originate from a semiquinone-type ~ompound.~-6When hydrogen gas was admitted into the reaction vessel, these peaks disappeared and only a peak around 295 mp was found, as shown in curve 3; this peak is assumed to be that of p-hydroquinone, but its assignment is rather uncertain because the absorption peaks of p-hydroquinone and a semiquinone-type compound exist in the same wavelength region. When the reaction vessel was heated a t 353'K overnight, The Journal of Phusical Chemistrg
Nuclear Magnetic Resonance Study of Hydrogen Bonding in Ethanol by W. L. Chandler and R. H. Dinius Department of Chemistry, Auburn Un$versttg, Auburn, Alabama (Received October 10, 1 9 6 8 )
Van Ness and coworkers' have recently reported the results of a rather thorough investigation of the infrared spectra of ethanol-n-heptane and ethanol-toluene midtures in the frequency range of the hydroxyl-stretching mode. These authors point out that the literature (1) H. C. Van Ness, J. Van Winkle, H. H. Richtol, and H. B. Hollinger, J. Phys. Chem., 7 1 , 1483 (1967).
