4417
NOTES
Table I: p K Values for Some Nitrophenols and for Salicylic Acid in Water and in Deuterium Oxide Compound
o-Nitrophenol p-Nitrophenol 2,PDinitrophenol Salicylic acid
Long and McDougall PKH APK
7.19 7.26 4.12 2.94
0.75 0.48 0.70 0.75
Bell and Kuhn PKH
AP K
...
...
... ...
4.07
0.52
...
...
Martin and Butler PKH APK
PKH
APK
7.25 7.24 4.02 3.00
7.22 7.14" 4.12 3.01
0.60 0.58 0.56 0.56
a R. Robinson and A. Peiperl give the value 7.156: J. Phus. Chern., 67, 1723 (1963). 624 (1936).
pointed out similar large discrepancies in the values reported by McDougall and Long and those of Martin and Butler3 for o-nitrophenol and p-nitrophenol. A summary of these values i;3 given in Table I. Noting that the results of McDougall and Long were obtained using the glass electrode to measure pH or pD whereas his results and those of Martin and Butler were made using spectrophotometry, Bell suggests the possibility that the glass electrode is not wholly reliable in deuterium oxide solutions. Since we have published several results for dissociation constants of acids in deuterium oxide using the glass electrode, we undertook the measurement of pKH and PKDfor the nitrophenols in question using the procedure described in an earlier notes4 The solutions were in general very dilute, usually less than 0.01 M , owing to the low solubility of the nitrophenols in water. The ionic strength was kept around 0.05 by addition of KCl. It was found that the glass electrode was much more stable in such a solution than it was in the nitrophenol alone. I n all cases, the pK values are corrected for the ionic strength using the Debye limiting law. The values we have obtained are shown in Table I. I n each case, our value checks reasonably well with Bell or with Martin and Elutler. I n view of these results, we conclude that in these cases the glass electrode gives proper results in deuterium oxide solutions. Long and McDougal12 report a value for ~ K .-D ~ K (or E ApK) for salicylic acid of 0.75. This is much higher than that given by La Mer and Korman,6 0.61. We have measured the PKD and the ~ K Efor I salicylic acid and obtain 0.56. We conclude that the deuterium isotope effect in salicylic acid is only slightly greater than that of "normal" carboxylic acids.'s6 (3) D. C. Martin and J. A. V. Butler, J . Chem. SOC.,1366 (1939). (4) P. K.Glasoe and L. Eberson, J. Phys. Chem., 68, 1560 (1964). (5) See footnote b of Table I. (6) C. K. Rule and V. K. La Mer, J. Am. Chem. Soo., 60, 1974 (1938).
0.57 0.56 0.52 O.6lb
This work
V. K. La Mer and S. Korman, Science, 83,
The Proton Magnetic Resonance Spectrum of Phenanthrene
by Robert C. Fahey and Gary C. Graham Department of Chemistry, University of California at San Diego, La Jolla, California (Received August 18, 1966)
The proton n.m.r. spectrum of phenanthrene (Figure 1) contains two complex multiplet patterns. Because inter-ring coupling constants are usually negligibly small in aromatic hydrocarbons, the 9,lO-protons should give rise to a single line. The intense line a t
the center of the high-field multiplet is reasonably assigned to these pr0tons.l The remaining lines in the spectrum comprise an ABCD pattern, the lowfield multiplet of which has been assigned to the 4,5protons based on studies of phenanthrene-9-dl and 4methylphenanthrene.2 An approximate analysis of the spectrum has been reported previou~ly.~We report here a complete analysis of the spectrum and compare our results with the earlier findings. Spectra were measured at several concentrations (8.9 to 17.4%, w./v.) in CDC1, on a Varian HR-60 spectrometer. Peak positions were determined relative to tetramethylsilane as internal standard using the side-band technique. The spectra were analyzed using (1) N. Jonathan, S. Gordon, and B. P. Dailey, J . Chem. Phys., 36, 2443 (1962). (2) H. J. Bernstein, W. G. Schneider, and J. A. Pople, Proc. Roy. SOC. (London), A236, 515 (1956). (3) T. J. Batterham, L. Tsai, and H. Ziffer, Australian J . Chem., 17, 163 (1964).
Volume 69, Number 12 December 1966
NOTES
4418
/I
an appreciable discrepancy in the chemical shift values, our values for a 10% solution being consistently to lower field by 0.28 to 0.32 p.p.m. Independent spectra were obtained on two different Varian A-60 spectrometers. The chemical shifts of the 9,lO-protons agreed satisfactorily ( f 0.02 p.p.m.) with our other results, lending credence to their accuracy. It may be noted that the low-field resonance lines are broader than the others. This might be the result either of long-range coupling or of a short relaxation time for the 4,5-protons. No significant narrowing of these lines was observed during spin-decoupling experiments in which the 9,lO-proton resonance was irradiated.
I Figure 1. Observed and calculated proton n.m.r. spectra of phenanthrene a t 60 Me.
the procedure and iterative computer program described by Swalen and re ill^.^ A variety of different line assignments was tested corresponding to different chemical shift assignments and relative signs for the coupling constants. Only one assignment gave satisfactory agreement for both the line positions and the line intensities. The observed and calculated spectra for a 13% solution are given in Figure 1. The analysis was checked by comparing the observed 100-Me. phenanthrene spectrum with that calculated from the parameters determined at 60 Mc., and good agreement was found. The coupling constants showed no significant variation with concentration over the range studied. The chemical shifts did vary, and values were extrapolated to infinite dilution. The results, together with values from the previous study, are shown in Table I.
Acknowledgment. We wish to express our appreciation to Varian Associates for supplying 60- and 100-Me. n.m.r. spectra of phenanthrene, to Dr. E. Wadsworth of San Diego State College for making an A-60 spectrometer available for our use, and to the National Science Foundation for partial support of this work as well as for a grant-in-aid assisting the purchase of the n.m.r. spectrometer used in these studies. (4)J. D. Swalen and C . A. Reilly, J. Chem. Phys., 37, 21 (1962).
Logarithmic Distribution Functions for Colloidal Particles
by E. P. Honig Philips Research Laboratories, N . V. Philips’ Glosilampenfabrieken, Eindhoven, The Netherlands (Received August 91, 1966)
Table I: Chemical Shifts and Coupling Constants for Phenanthrene - 6 ~ ~ 8
i
1 2 3 4 9
- &$I,
10% in CDClP
8.125 7.825 7.883 8.933
~ J . j j0.p.8.,
p.p.m.-
This
Inf. dil. in CDClsb
work
(k0.006)
CJ’
Ref. 3
(&O.OS)
7.855 7.570 7.612 8.648 7.702
12 13 14 23 24
8.4 1.6 0.5” 7.3 1.6 8.4
8.11 1.31 0.66 7.20 1.24 8.40
34
Recently, Espenscheid, Kerker, and Matijevi6I stated that a set of different logarithmic distribution functions p,(r) was obtained by varying a parameter n of the “general” logarithmic distribution function (eq, 21 of their paper), characterized by the three parameters n, r,, and a, P,(T>
a
See ref. 3.
This work.
Assumed.
The coupling constants found here are generally similar to those reported earlier,3 but some differences do occur, It should be pointed out that the previous analysis was based on an interpolation procedure, and JI4 was assumed to be 0.5 C.P.S. There is also The Journal of Physical Chernistru
=
rnexp [- (In T - In rn)2/2an2] 2/2?ra,rnn+lexp[(n 1>zan2/2]
+
(1)
However, it will be shown now that all distribution functions (1) can be reduced to the logarithmic normal distribution function, containing only two parameters: r, and a., (1) W. F. Espenscheid, M. Kerker, and E. MatijeviO, J . Phys. C h m . , 68, 3093 (1964).
