228
J. Phys. Chem. 1980, 84, 228-229 1
-1
400
300
i,
/ DPPH
500
h.(nrni
Figure 1. Low-resolution spectrum of argon-saturated CuS04 solution (0.1 M) insonated at 459 kHz.
kinetic energy of the products formed at room temperature is -0.5 kcal/mol, the dissociation energy at room temperature is 90.1 - 0.5 = 89.6 kcal/mol, in good agreement with the thermal value of 90 f 4 kcal/m01.~H,O, formed during the sonolysis of the aqueous solutions will most likely reoxidize SO3*-and so it would be very difficult to detect analytically. The diffuse band in the green at -500-550 nm arises from the formation of CuOWlo in an ultrasonic field, i.e.
Figure 1. ESR spectrum of bromothiophenol with sodium nitrite in methanol at room temperature.
-
Cu2+
USF
H,OH
CuOH
Excited copper may also be formed with resonance lines a t 324.7 and 327.4 nm but this emission would be imbedded in the broad continuum due to the association of H and H02. In conclusion, the sonoluminescence spectrum of CuS04 solution is found to be composed of a broad continuum arising from the radiative association of H and H 0 2 and emission from CuOH and it is likely that the HOz is formed by a reaction of hydroxyl radicals with sulfate anions. Further kinetic studies are required to confirm this postulate.
References and Notes (1) E. L. Mead, R. G. Sutherland, and R. E. Verrail, Can. J. Chem., 54, 1114 (1976). ( 2 ) 6. Sehgal, R. P. Steer, R. G. Sutherland, and R. E. Verrall, J . Chem. Phys., 70, 2242 (1979). (3) C. Sehgal, R. P. Steer, R. G. Sutherland, and R. E. Verrall, J . Phys. Chem., 81, 2618 (1977). (4) C. Sehgal, R. G. Sutherland, and R. E. Verrall, J . Phys. Chem., accepted for publication. (5) K. J. Taylor and P. D. Jarman, Aust. J . Phys., 23, 319 (1970). (6) T. K. Saxena and W. L. Nyborg, J . Chem. Phys., 53, 1722 (1970). (7) M. A. Margulis, Russ. J . Phys. Chem., 52 (3), 342 (1978). (8) C. Sehgai, R. G. Sutherland, and R. E. Verrali, J . Phys. Chem., accepted for publication. (9) P. Gray, Trans. Faraday SOC.,55, 408 (1959). (10) J. A. Dean and S. Hanamura, "Flame Emission and Atomic Absorption Spectrophotometry", J. A. Dean and T. C. Raine, Ed., Vol. 3, Marcel Dekker, New York, 1975. Department of Chemistry and Chemical Engineering University of Saskatchewan Saskatoon, Saskatchewan Canada, S7N OW0
C. Sehgal R. G, Sutherland R. E. Verrall"
Figure 2. ESR spectrum of bromothiophenol with 15N-labeledsodium nitrite in methanol at room temperature.
0.002 mT, was observed when various substituted thiophenols (p-bromothiophenol, p-chlorothiophenol, p thiocresol) were treated with equimolar amounts of NaNOz in methanol at room temperature (Figure 1). The relative spectral intensities observed (1:2:3:2:1) are suggestive of the presence of two equivalent nitrogen nuclei ( I = 1). With 15N-labeledNaNOZ,a three-line ESR spectrum was observed with intensity ratios of 1:2:1 and g = 2.028 f 0.002, a N = 0.325 m T (Figure 2), again indicating the presence of two equivalent nitrogen nuclei ( I = l/z) in the radical species. Other reactions involving substituted thiophenols with a methanol solution of a C-nitroso compound [tert-nitrosobutane (t-NB)], N-nitroso compounds (N-nitrosodiethylamine, N-nitrosodibutylamine, N nitrosopyrrolidine), or nitrosyl chloride (generated in situ by bubbling NO gas into an air-saturated, KCl-methanol solution) also exhibited similar five-line ESR spectra. 15N-labeled diethylnitrosamine (I) was synthesized by CH3CH2 \14
/
N-
15
N=O
CH3CH2
.
I
the nitrosation of diethylamine with 15N-labeledNaNOZe4 Unreacted nitrite was then removed by the addition of excess ammonium su1famate.l When I was treated with p-bromothiophenol in methanol, a three-line ESR spectrum with the same g factor and uN value as the 15N-laESR Study of the Radicals Generated in the Reaction beled nitrite-thiolphenol reaction was observed. This result clearly indicates that the nitrogen adjacent of Thiophenols with Nitroso Compounds to the alkyl group was not involved in the radical species Publication costs assisted by the Food and Drug Administration which gave the five-line ESR spectrum for N-nitroso compounds. Consequently the radical species proposed Sir: Thiols, in the presence of N204or sodium nitrate, can by Waters (11)in the reaction of N-nitrosopiperidine and be converted into the corresponding thionitrates (RSN= 0);in the presence of excess thiols, disulfides are f~rmed.l-~ N-nitrosodiethylamine with thiol compounds5 is probably not the structure of the intermediate. Results from our In these reactions, a five-line ESR spectrum, with the ESR studies support the initial formation of thionitrite relatively high g value of 2.028 f 0.002 and uN = 0.235 f Received July 30, 1979
This article not subject to U S . Copyright. Published 1980 by the American Chemical Society
J. Phys. Chem. 1980, 84, 229-230 R\
R
/
/OS
N-N
‘SR‘
I1
(RSN=O) intermediates, and the subsequent trapping of the NO radical: RSNO + XH RSH + X-NO (1)
+ -
where X = R2:N, tert-butyl, NaO, or C1 RSNO RS- NO. RSNO
+ NO.
(2)
RSN N=O)O* $11
(3)
Paramagnetic species can also be produced from reaction of NO with ferrous iron containing ligands. Results from the ICP optical emission spectroscopy indicated that the thiols in question are almost void of iron impurity ( < 2 ppm). It, was reported3 that thionitrites, in the presence of secondary amines, produce N-nitrosamines. A detailed knowledge of the mechanism of the reaction of nitroso compounds with thiols is pertinent, since it may involve the formation as well as the inhibition of the carcinogenic N-nitrosamines.
Figure 1. Capacity ratio k , of naphthalene as a function of pressure at three supercritical temperatures measured in a chromatographic column filled with silica gel (Perisorb A; surface 14 m2 g-’) as ithe stationary phase and carbon dioxide as the mobile phase.
plbar
Acknowledgment. We thank Drs. E. Ragelis and A. Pohland for helpful discussions and Mr. J. Jones for running samples in the ICP spectrometer. References and Notes (1) B. Saville, Analyst, 83,670 (1958). (2) S. Oae, Y. K:im, D. Fukushima, and T. Takata, Chem. Lett., 833 (197’7). (3) S.Oae, D. Fukushima, and Y. Kim, J. Chem Soc., Chem. Commun., 407 (1977). (4) H. H. Hatt, “Organic Syntheses”, Collect. Vol. 11, Wiley, New York, 1943,p 211 (5) W. A. Waters, J . Chem. Soc., Chem. Commun., 741 (1970). Division of Chemistry and Physics Food and i3rug Administration Washington, D.C. 20204
George C. Yang” Avlnash Joshl
Received July 16, 1979
Flgure 2. Partial molar volumes V,” of naphthalene and fluorene at infinite dilution in supercritical carbon dioxide [(V)naphthalene, stationisry phase Perisorb A; (A) naphthalene, stationary phase Perisorb RP 8; (0) fluorene, stationary phase Perisorb A; (0)fluorene, stationary phase Perisorb RP 8; (--) isothermal compressibility K of pure CO, (from ref
411.
Partial Molar Volumes of Naphthalene and Fluorene at Infinite Dilution in Carbon Dioxide near Its Critical Point Publication costs assisted by the University of Bochum
Sir: Critical phenomena in pure compounds and mixtures are of rapidly increasing interest. In this paper partial molar volumes of organic substances at infinite dilution in carbon dioxide near its critical point are presented. These data have been obtained from supercritical fluid chromatography (SFC); it would have been difficult to determine these data with other (e.g., static) methods. In the chromatographic process the sample (2) is distributed between the supercritical solvent (1, here supercriticitd C02) in the mobile phase (’) and the stationary phase (” here two different adsorbents). The partition coefficient K 2 E: cz/’/c; determines the capacity ratio k z (ci’/ci) (V”/V’) where V” and V’ are the volumes of the stationary phase (that is assumed to be proportional to the surface) and the mobile phase, respectively, with the concentrations of the sample in the two phases being c2” and c2/. The basic chromatographic equation kz -- ( t R 2 - to)/t, (1) 0022-3654/80/2084-0229$01 .OO/O
relates the capacity ratio k z to the retention time tR2of the sample 2 and to the time toan inert particle needs to travel through the column. For the thermodynamic description a model was chosen that was derived for adsorption from solutions.2 Its application on the chromatographic process yields a simple expression for the capacity ratio hz and the pressure dependence is found to bell3
(a In k2/ap)T =: (V2”’- (az/al)Vl*’)/RT(1/ P ’ ) (ap’/ap)?- (2)
Here Vzm’is the partial molar volume of the sample in the solvent at infinite dilution, VI*’ the partial molar volume of the nearly pure solvent, p’ the bulk density of the mobile phase, and thus (l/~’)(ap’/ap)~ the isothermal compressibility K ; al and a2 are the partial molar areas on the surface occupied by species 1 and 2 . In the experiments hz has been determined for naphthalene and fluorene by using two different stationary surfaces (Perisorb A; Perisorb RP8) at three temperatures each over a wide range of pressure. One set of data is shown in Figure 1. From these data the partial molar volumes have been calculated according to eq 2. For VI*’ the molar volume of pure GO2*was uaed and a 2 / a 1was roughly estimated to be the ratio of the molar volumes of the pure soliid 0 1980 American
Chemical Society
