Photolysis of Mixtures of Acetoned 6 and Diethyl KetoneM. H. J. Wijnen Citation: The Journal of Chemical Physics 22, 1631 (1954); doi: 10.1063/1.1740501 View online: http://dx.doi.org/10.1063/1.1740501 View Table of Contents: http://scitation.aip.org/content/aip/journal/jcp/22/9?ver=pdfcov Published by the AIP Publishing Articles you may be interested in Studies of the 193 nm photolysis of diethyl ketone and acetone using timeresolved Fourier transformemission spectroscopy J. Chem. Phys. 102, 6660 (1995); 10.1063/1.469139 Deuterium quadrupole coupling in solid complexes of diethyl ether, acetone, and mesitylene withchloroformd J. Chem. Phys. 60, 3184 (1974); 10.1063/1.1681504 Photolysis of Mixtures of Diethyl Ketone and Carbon Tetrachloride J. Chem. Phys. 38, 2925 (1963); 10.1063/1.1733621 Photolysis of Mixtures of Cyclobutane and Acetoned 6. Reactions of the Cyclobutyl Radical J. Chem. Phys. 36, 824 (1962); 10.1063/1.1732616 The Photolysis of Methylethyl Ketone J. Chem. Phys. 8, 466 (1940); 10.1063/1.1750690

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LETTERS TO THE EDITOR 1631

Photolysis of Mixtures of Acetone-d6

and Diethyl Ketone M. H. J. WI]NEN

Division of Pure Chemistry. N altonal Research Council, Ottawa, Canada

(Received July 9, 1954)

T HE photolysis of mixtures of acetone-ds and diethyl ketone has been studied over the temperature range 27 to 200°C.

If acetone-ds and diethyl ketone are photolysed separately, the following reactions have been shown to occur. I-a

2CDs->C,Ds, (1)

CD 3+CD,COCDa->CD,+CD2COCD3 (2)

(3)

2C 2H,->C,H,+C,H., (4)

C2H.+C,H5COC,H5->C,Hs+C,H,COC,H" (5)

C,H,COC,H5->C,H,+CO+C,H5. (6)

When, as in our case, mixtures of acetone-ds and diethyl ketone are photolyzed then, in addition, the following main reactions may be expected to occur.

CDa+C,H,COC,H5->CDaH +C2H,COC 2H 5, (7)

CDa+C,H5->CaH5Da, (8)

CD3 +C,H5->CD3H+C2H" (9)

C,H5+CDaCOCDa->C,H.D+CD,COCDa. (10)

As expected from the reaction mechanism above, the reaction products are CO, CD" CDaH, C,D., C,DsH, C,Hs, C2H" CaH5Da, and C,H,o. The products were separated by fractionated distilla­tion and analyzed by mass spectrometer. Because of overlapping of the ethane spectra, no accurate results could be obtained for C,H5D and C,Hs.

From the reaction mechanism, the following equations may be derived, where Rx means the rate of production of the com­pound X.

R'CaH 5D a RC,Ds·Rc,H,O

RCDaH =k7/k2 RCD, . (DK) +k./kg

,

RCaH5Da RCaH5Da (Ac-d.)

RCDaH ._1__ iii Rlc,HIO RtC,Ds (DK) -k7/kI +k./(k, ka ) (DK) ,

RCDaH (Ac-d.) iRic,HIO RCD,' (DK) = k7/k,+k./k 2ka (DK)'

I

II

III

IV

This investigation was carried out mainly to obtain information about reactions (8) and (9). It could, however, be shown at 141°C, where a larger series of experiments was carried out, that the results are correctly expressed by the foregoing equations. By plotting RCDaH/ RCaH5Da against RCD,/ RCaH5DaX (DK) / (Ac-ds) we obtained a straight line going within experimental error through the origin. From the slope of this line we obtained kr/k2=56.1 (141°C). The fact that the line passes within experi­mental error through the origin indicates that k./ kg is small. At 141°C RCDaH/RIC,DsX1/(DK) and RCDaH/RcD,· (Ac-ds)/(DK) are independent of Rlc,Hlo/ (DK) indicating that Rlc,H,o/ (DK) is small compared to kr/k,i and kr/k,.

From equations IV and V we obtained kr/k,I=80X 1013 cm! molecules-i sec! at 141°C and kr/k2 =57.2 (141°C), the latter result in good agreement with that obtained by Eq. II.

Equation I indicates that the product R'CaH5Da/Rc,Ds'Rc,Hlo is constant, independent of pressures of acetone-ds and diethyl ketone. This has been found to be correct, and in Table I we give the average values found for kB'/kIka at the different temperatures of this investigation. Column 2 gives the number of experiments, from which the average values for kB'/k,k, are calculated, and

column 3 gives the extreme values of PCDaCOCDa/ PC,H,Coo,H5 for these experiments.

Since reaction 9 produces CDaH and C,H, which are also pro­duced by other reactions, it is difficult to obtain quantitative information about this reaction. The fact that within experimental

TABLE 1. Values of k,'/kIk,.

Number of Temperature °C experiments PAo/PDK k,'/klk,

27 8 6.4-1.0 3.4 108 5 5.5-0.4 2.7 141 12 2.8-1.1 3.4 197 7 4.6-0.5 3.4

error no intercept was found when plotting RCDaH/ RCaH5Da against RCD,/RcaH5Da' (DK)/(Ac-ds) indicates that k./kg is small. CD ,H is produced by reactions (9) and (7). At room tem­perature the amount of CDaH produced by reaction 7 is small. The ratio RCDaH/RcaH5Da will therefore give us at room tempera­ture a maximum value for kg/kg. The maximum value for RCDaH/ RCaH.Da at room temperature was 0.08, therefore kg/kg <0.08. If we compare our value of kg/kg with the value k./ka=0.13±0.02,' then there seems no doubt that the rate of disproportionation over recombination is smaller for methyl plus ethyl radicals than for two ethyl radicals.

1 A. F. Trotman.Dickenson and E. W. R. Steade, J. Chern. Phys. 18, 1097 (1950).

2 M. H. J. Wijnen and E. W. R. Steade, Can. J. Chern. 29, 1092 (1951). 'Kutschke, Wijnen, and Steade, J. Am. Chern. Soc. 74, 714 (1952). 4 P. Ausloos and E. W. R. Steade, Bull. soc. chim. Belges. 63, 87 (1954).

Simultaneous Vibrational Transitions in the Infrared Absorption Spectra of

Compressed Gases* J. FAHRENFORT AND J. A. A. KETELAAR

Laboratory for General and Inorganic Chemistry of the University of Amsterdam, Amsterdam, The Netherlands

(Received June 28, 1954)

I N the course of our investigations on the infrared absorption spectra of compressed gases,' we have found that on the addi­

tion of nitrogen to carbon dioxide two bands appear, not observed in pure compressed CO,.

We used an optical path length of 100 cm with a pressure of 20 at of CO, and nitrogen added to a total pressure of 75 atmos.

The intensity of these bands at 2994±3 cm-1 and at 4670±5 cm-I varies proportionally both with the density of the N, and with that of the CO,.

These facts can most readily be explained only by attributing the new bands of simultaneous transitions in each of the two partners of the CO, - N 2 collision complex, the CO, molecule performing one of its fundamental allowed vibrational transitions at 667.3 cm-1 (VI) and at 2349.3 cm-I (V3), simultaneously with the fundamental vibrational transition of 2330.7 cm-I in the N, molecule.

The calculated frequencies of 2998 cm-I and 4680 cm-I show a very good correspondence with the observed values given above.

A further confirmation of the explanation of these bands as due to simultaneous vibrational transitions is gained from the ob­servation of analogous bands in mixtures of carbon dioxide with oxygen and with hydrogen.

We have indeed found a band in 20 at CO, and oxygen added to 75 atmos pressure, due to the transition expected at 1554.7 (0,) +2349.3 (CO,) =3904 cm-I observed at 389S±5 cm-I. One band expected at 4160.2 (H,) +2349.3 (CO,) =6509.4 cm-I was observed at 6505±7 cm-I, already with 10 atmos carbon dioxide and hy­drogen added to a total pressure of 27.5 atmos.

Both combinations with the deformation frequency of CO,

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1632 LETTERS TO THE EDITOR

at 667.3 cm-1 could not be observed as a consequence of the strong absorption of CO2 in the corresponding regions.

Our results indicate that simultaneous vibrational transitions arising from collision complexes, as predicted by van Kranendonk,2 are indeed observed as a quite general phenomenon in pressure induced infrared absorption spectra of mixtures.

In pure gases it will always be difficult to distinguish between the simultaneous transition in a pair of molecules and the corre­sponding combination frequency (pressure induced transition) in a single molecule.

The appearance of the simultaneous transitions must be pri­marily ascribed to the polarization of the symmetrical two­atomic molecule by the electric field of the rather large quad­rupole moment arising from the partial dipoles present in the CO2 molecule.

* Research supported by the Section of Molecular Physics III of the F.O.M. .

1 Fahrenfort. de Kluiver, and Babeliowsky, J. phys. (to be publIshed). 2 J. van Kranendonk, thesis, University of Amsterdam (1952); J. van

Kranendonk and R. B. Bird, Physica 17, 953, 968 (1951).

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