968
NOTES
temperature region studied (1273- 1513OK.) is defined by
and acetophenone, and that no such specificity of product formation is displayed by isobutyrophenone or benzoylcyclopropane. The parallel with the Norrish Type I1 photolytic reaction of aliphatic ketones2-' suggested that similar mechanisms may be important Using the available values for the entropies of solid in radiolysis and photolysis of phenyl alkyl ketones. and gaseous RIgFz3 coupled with the experimentally At the same time, the paper reported failure to find determined vapor pressures, a third-law value for any correlation between these results and mass spectra. AH298sUt, of RIgF, of 83.95 f 0.64 kcal./mole is obThe spectra were stated to be so similar as to be useless tained. The excellent agreement between secondfor predicting how radiolytic reactions of the three and third-law values obtained in this investigation for ketones might differ. The present writer furnished AHZgasUb of IZIgF, coupled with the fine agreement) of the spectra referred to, but does not concur in this the AS298sub with the theoretical value of 42.2 cal./ judgment. deg./mole confirms the previous experimental obThe statement cited is correct if only the grossest servation that the vapor species above MgF2(c) conspectral features are taken into consideration. For sists of only MgF,(g) within experimental error (1-2%). example, the three most intense fragment-ion peaks in The value of AH298sub obtained in this work is in each of the three spectra are those due to C?H60+, reasonably good agreement with the value previously COH5+,and C4H3+,of masses 105, 77, and 51. Among calculated3 by combining the vapor pressure data peaks of lower intensity, however, the partial spectra of the liquid1 and the melting point and heat of fusion2 shown in Table I reveal significant differences, some of (85.6 i 1.0 kcal./mole), and the third-law value of which parallel closely differences found in radiolysis. Berkowitz4 (-85 kcal./mole). It should also be menIn particular, the normal peak a t 120 and the nietationed that the vapor pressure of R4gF2(c) a t 145OOK. stable peak a t 97.3 arise from primary rearrangementreported by Berkowitz4 (2.8 x 10-5 atm.) is only about dissociation of n-butyrophenone to ethylene and acetoone-third of the measured value (7.3 X atm.) phenone (enol) ions; no indication of an analogous reported here. Based on the excellent agreement beprocess is observed In the spectra of isobutyrophenone tween the second- and third-law values for AHZgBsUb and benzoylcyclopropane. This reaction, characterobtained in the present investigation, coupled with the istic of a wide variety of carbonyl compounds under very large number of points obtained in the 240' electron impact provided they have the requisite structemperature range studied, it is considered that the tural features, has been shown6 to parallel precisely present vapor pressure curve and the heat and ent)ropy the Norrish Type I1 photolysis of aliphatic ketones. of vaporization reported here are more definitive than Admittedly, the reaction leading to acetophenone in those previously reported. radiolysis of n-butyrophenone looms far larger than the It should be pointed out that in this investigation, analogous reaction in the mass spectrum. Such a difin which two effusion cells were employed having oriference might have been anticipated even if reaction fice areas differing by a factor of four, no dependence mechanisms in radiolysis were assumed identical with of the vapor pressure on orifice area was observed. This is consistent with previous experimental observa(1) D. J. Coyle, J . P h y s . Chem., 67, 1800 (1963). tions made in this laboratory in studies of BeFZ5and (2) R . G. W. Norrish, Trans. Faraday Soc., 33, 1521 (1937); Wr. Davis and W. A. Noyes, 6.Am. Chem. Soc., 69,2153 (1947); J. R. BeC12,6where orifice areas of cells were varied by as McNesby and A. S.Gordon, ibid., 80, 261 (1958); N. C. Yang and much as a factor of sixteen. D. H. Yang, ibid., 80, 2913 (1958); P. husloos and E. Murad, ihid., 8 0 , 5929 (1958); R. Srinavasan, ibid., 81, 5061 (1959); P. Ausloos,
Mass Spectra, Radiolysis, and Photolysis
of Phenyl Alkyl Ketones
by Seymour Meyerson Research and Deuelopment Department, American Oil C o m p a n y , W h i t i n g , I n d i a n a (Received October 31, 1963)
A recent paper1 reported that radiolysis of n-butyrophenone is dominated by a reaction leading to ethylene The Joikrnal of Physical Chemistry
J . P h y s . Chem., 65, 1616 (1981); R. P. Borkowski and P. Ausloos, ibid., 6 5 , 2257 (1961). (3) The well-known correspondence between primary rearrangementdissociation reactions of aliphatic ketones in photolysis and under electron impact [A. J. C. Nicholson, T r a n s . Faraday Soc., 50, 1067 (1954); T.W.Martin and J. N . Pitts, J . Am. Chem. Soc., 77, 5465 (1955); P.P. Manning, ibid., 79, 5151 (1957); F. W. McLafferty, A n a l . Chem., 31, 82 (1959)l was recently extended to include also radiolysis [J. N. Pitts and A. D. Osborne, J . Am. Chern. Soc., 83, 3011 (1961)l. (4) Reference 1 reports, on the basis of preliminary experiments, that "the photolysis with 2537--k. radiation of the neat aralkyl ketones in zacuo yields products anticipated on the basis of the photochemistry of dialkyl ketones." (5) 8 . Neyerson and J. D. McCollum, Advan. A n a l . Chem. Instr., 2 , 179 (1963), and references cited there.
NOTES
969
Table I : Partial Mas8 Spectra of Phenyl Alkyl Ketones"
-
~ n-CsH1
'L'-CIH~ Relative intensity-------
2.33 1.60 0.40 1.26 7.21 16.0 37.9 2.75 0.30
2.38 2.18 0.34 1.40 7.28 15.5 47.6
Mass
39 41 42 43 51 77 105 120 Parent less 1 Parent
Alkyl group-----------~
6.00
cycloCsHs
4.89 3.63 0.28 0.12 7.41 13.6 27.5 0.01 1.84 7.56
0.01 0.06 2.78
Metastable peaks corresponding to primary reaction stepsb
74.5 75.5 97.3 144.0 146.0
0.06
0.08
...
...
, . .
0.15 ... 0.04
...
0.69 ... 0.13
, . .
...
, . .
'Transitions denoted by metastable peaksh
74.5 75.5 97.3 144.0 146.0
+ + + +
(148 +) + (1O5+) 43 (146+) -+ ( 1 0 5 + ) 41 ( 1 2 0 + ) f 28 (148+) ( 1 4 6 + ) + (145+) 1 (148+) -+ (147 +) 1
-
(6) H. M. Grubb, C. H. Ehrhardt, R. W. Vander Haar. and W. H. Moeller, presented before ASTM Committee E-14 on Mass Spectrometry, Los Angeles, Calif., May, 1959.
a Total ion inhensity = 100.0. No corrections made for contributions of naturally occurring heavy isotopes. 6 For interpretation of metastable peaks, see ref. 5.
those in the mass spectrometer. Extrapolation of results from the gas phase a t lop6 torr to the liquid phase may be possible for primary reaction steps and especially for low-energy processes, but would seem progressively less likely for succeeding steps and for higher-energy processes. Moreover, involvement in radiolytic processes of reactive intermediates, such as those appearing in mass spectra, might well be obscured in the ultimaie reaction products even if the latter were all isolated and identified. Common intermediates and reaction paths in mass spectra-as in photolysis-and radiolysis of phenyl alkyl ketones are certainly not established by available evidence. However, the parallel is striking. Interpreted with care, mass spectra can furnish helpful guidance in exploring radiolytic systems. Experimental Mass spectra were measured with 70-v. electrons on a modified6 Consolidated 21-103 instrument with the sample-introduction system a t 250'.
Charge-Transfer Complqxes of
Oxygen and Inorganic Anions
by G. Kavon Department of Physical Chemistry, The Hebrew University, Jerusalem, Israel (Received October 31, 196.9)
Oxygen was recently found to bring about an extra light absorption when dissolved in various solvents. - 5 The linear dependence of the transition energy on the ionization potential of the solvent molecule has led to the conclusion that this absorption is of chargetransfer type. 1,4,5 For the same reason Meyerstein and Treinin,6 following the suggestion of M ~ l l i k e n , ~ concluded that the spectrum of the trihalide ions is also of charge-transfer character, where the halogen molecule acts as an acceptor and the halide ion as a donor. The purpose of this note is to present spectroscopic evidence for the existence of analogous complexes between oxygen and the iodide, bromide, chloride, and thiocyanate ions in solution. Experimental Materials. The oxygen used was the Extra Dry Grade of the Matheson Co., with minimum purity of 99.6%. The nitrogen was the Perpurified Grade of the Matheson Co., with minimum purity of 99.996%. Water was triply distilled. Ethylene glycol of RiedelDe Haen Ag. was distilled in vucuo. All other chemicals were of A.R. grade without further purification. Spectrophotometric measurements were carried out a t room temperature (24 l o )using a Hilger Uvispek spectrophotometer. Quartz cells (4 cm.) with ground glass stoppers were used. Procedure. All solutions were near neutral pH. No buffers were used. Oxygen was bubbled through the solutions for 5 min. and the absorption spectra were
*
(1) D. F. Evans, J . Chem. Soc., 345 (1953); J . Chem. P h y s . , 23, 1424
(1955). (2) .A. U. Munck and J. F. Scott, Nature, 177, 587 (1956). (3) L. J. Heidt and L. E. Ekstrom, J . Am. Chem. Soc., 79, 1260 (1957). (4) H. Tsubomura and Ii. 5. Mulliken, ibid., 82, 5966 (1960). ( 5 ) J. Jortner and C . Sokolov, J . P h y s . Chem., 6 5 , 1633 (1961). (6) D. Meyerstein and A. Treinin, T r a n s . Faraday SOC., 59, 1114 (1963). (7) R. S. Mulliken, J . Am. Chem. SOC.,72, 600 (1950).
Volume 68, N u m b e r .4
A p r i l , I 96.4
