ES&T
CRITICAL REVIEW
Fourier transform infrared (FTIR) studies are being conducted to answer questions concerning the chemical mechanism of
Atmospheric ozone—olefin reactions
Hiromi Niki Paul D. Maker Carleton M. Savage Larry P. Breitenbach Ford Motor Company Research Staff Dearborn, Mich. 48121 Among various classes of organic compounds present in the troposphere, the olefins are unique in exhibiting significant reactivity toward ozone (O3) as well as toward the hydroxyl ( H O ) radical. Numerous potentially important roles of the 0 3 -olefin reac tions have been recognized for some time. Tn brief, these reactions can provide mutual sinks for both O3 and the olefins and concomitantly serve as sources for partially oxidized com pounds, e.g., C O , aldehydes, ketones, and organic acids. Some of the inter mediates formed in the 03-olefin re actions can also lead to HO-radical chain reactions, regenerate O3 by ox idizing N O to NO2, and convert SO2 to sulfate aerosols. Existing theoretical and experimental bases for these re action mechanisms have been reviewed recently by Herron and his co-workers ( 5 ) . A general scheme for the 0 3 olefin reactions, which emerged over the years, can be represented by reac tion 1 followed by reactions 2a-2d. 312A
Environ. Sci. Technol., Vol. 17, No. 7, 1983
General scheme for 03-olefin reactions In memoriam: Bernard Weinstock This article is based largely on ma terial presented at the Atmospheric Chemistry Symposium, held at the 1981 Fall National American Chemical Society Meeting in New York and or ganized by the late Bernard Weinstock. (It also contains additional updated information.) For that meeting, Wein stock had suggested that Hiromi Niki address unanswered questions con cerning the mechanism of gas-phase reactions that are important in the troposphere. Comprehensive assessments of chemical kinetics data needs for modeling purposes are made from time to time by various groups ( 1, 2). This article is therefore intended pri marily to illustrate the current status of knowledge and to point out as-yet un answered questions raised by ongoing Fourier transform infrared (FTIR) studies of the reactions between ozone (0 3 ) and several different types of olefins, such as simple mono-, di-, chloro-, and cyclic olefins.
\
>=
c +
/
O ^ O
\
* — {y?—K)
—*. ^ c — 0 0 + ^ > r = o
(i)
Criegee intermediate J^C
0 0 —*• decomposition
(2a)
(for example, CO, C0 2 , RH, R 0 2 , RCO;R = H or alkyl) —>- isomerization
(2b)
+ RCHO —*• products, Ο Ο such as \ . l \y (2c) 2 in the diluent air. Notably, the carbon balance is seen to be extremely poor, and the residual spectrum in Figure 1 Ob represents the missing products. In addition to the conspicuous C = 0 stretch band cen tered at 1747 cm - 1 , this spectrum ex hibits the aldehydic C—Η stretch bands at 2719 and 2815 cm - 1 , but it does not correspond to a straightchain monoaldehyde of the form C„H 2n CHO (n < 4). Also, there is at least one Ο—Η stretch band in the region of 3600 c m - ' . It is not certain whether all of these bands pertain to one major species or to a variety of secondary products in cluding aerosols. In fact, the carboncontaining products in reaction 18 are likely to be free radical species that must undergo subsequent reactions to yield stable products. Additional mechanistic complications can arise from the fact that the formation of the Criegee intermediate in reaction 17 is not accompanied by a stable aldehydic product. Thus, the bimolecular reac tions involving the Criegee interme diate in this case may be somewhat different from those of the straight-
3 (a) b (b) c
is the spectrum after ~ 10 min. is the residual spectrum obtained from (a). Numbers in parentheses represent ppm.
Environ. Sci. Technol., Vol. 17, No. 7, 1983
321A
(3) (a) Herron, J. T.; Martinez, R. I.; Huie, R. E. Int. J. Chem. Kinet. 1982,14, 201 and 205; (b) Martinez, R. T.; Herron, J. T. / . Environ. Sci. Health 1981, A16,623; and (c) Martinez, R. T.; Huie, R. E.; Herron, J. T. / . Am. Chem. Soc. 1981, 103, 3807. (4) Maker, P. D.; Niki, H.; Savage, C. M.; Breitenbach, L. P. Am. Chem. Soc. Symp. Ser. 1981, 103, 3807. (5) Niki, H.; Maker, P. D.; Savage, C. M.; Breitenbach, L. P. "Spectroscopy in Chem istry and Physics: Modern Trends"; Elsevier; Amsterdam, 1980; pp. 1-15. (6) Bell, R. J. "Introductory Fourier Transform Spectroscopy"; Academic Press: New York, 1972. (7) Su, F.; Calvert, J. G.; Shaw, J. H. J. Phys. Chem. 1980, 84, 239. (8) Niki, H.; Maker, P. D.; Savage, C. M.; Breitenbach, L. P. J. Phys. Chem. 1981,55, 1024. (9) Su, F.; Calvert, J. G.; Shaw, J. H.; Niki, H.; Maker, P. D.; Savage, C. M.; Breitenbach, L. P. Chem. Phys. Lett. 1979, 65, 221; and Niki, H ; Maker, P. D.; Savage, C. M.; Breit-
enbach, L. P. Chem. Phys. Lett. 1980, 75, 533. (10) Niki, H.; Maker, P. D.; Savage, C. M.; Breitenbach, L. P. Chem. Phys. Lett. 1981, 80, 499. (11) Niki, H.; Maker, P. D.; Savage, C. M.; Breitenbach, L. P. J. Phys. Chem. 1980,84, 14. (12) Sanhueza, E.; Hisatsune, I. C ; Heicklen, J. J. Chem. Rev. 1976, 76, 801. (13) Niki, H.; Maker, P. D.; Savage, C. M.; Breitenbach, L. P.; Martinez, R. I.; Herron, J. T. J. Phys. Chem. 1982, 86, 1858. (14) Japar, S. M.; Wu, C. H.; Niki, H. /. Phys. Chem. 1974,75,2318. (15) Adenji, S. Α.; Kerr, J. Α.; Williams, M. R. Int. J. Chem. Kinet. 1981,13, 209. ( 16) Groblicki, P. J.; Neble, G. J. "The Photo chemical Formation of Aerosols in Urban Atmospheres"; Tuesday, C. S. Ed.; Elsevier: New York, 1971; pp. 24-264. (17) Ripperton, L. Α.; Jeffries, Η. Ε. Advanced Chemistry Series; American Chemical Soci ety: Washington, D.C., 1972; Vol. 113, p. 219.
FIGURE 11" •"•"
An ozone-cyclohexene reaction (a) Cyclohexene (10 ppm) + O3 (5 ppm) in air at 700 torr; t - 10 min
Hiromi Niki is a senior staff scientist in the Chemistry Department, Chemical Sci ences Laboratory, Research Staff, Ford Motor Company, Dearborn, Mich. His research interests include gas-phase ki netics, photochemistry, atmospheric chemistry, and chemistry of combustion. Niki was the recipient of the 1980 F. Chambers Award {Air Pollution Control Association). He has served on a number of national panels and committees in volved with research and environmental concerns. Niki is on the editorial board of the Journal of Physical Chemistry. He received his MS and PhD from Carnegie Institute of Technology. Paul D. Maker is α principal research scientist in the Physics Department, Ma terial Sciences Laboratory, Research Staff, Ford Motor Company, Dearborn, Mich. His current research interests are in the areas of molecular and Fourier transform infrared spectroscopy, and at mospheric chemistry. Maker is an asso ciate editor of Optic Letters. He was in volved in early research in pulsed ruby lasers and nonlinear optical phenomena. He received his BSE, MS, and PhD in physics from the University of Michigan.
Carleton M. Savage is α research engineer in the Physics Department, Material Sci ences Laboratory, Research Staff, Ford Motor Company. His current research interests are in the areas of atmospheric chemistry and Fourier transform spec troscopy. He was previously involved in research of nonlinear optical phenomena and pulsed ruby lasers. He received his BS in physics and mathematics from Eastern Michigan University, an MS degree in physics from Michigan State University, and an MBA in finance from the Univer sity of Michigan.
a (a) b (b) c
is the spectrum after - 10 min. is the residual spectrum obtained from (a). Numbers in parentheses represent ppm.
322A
Environ. S c i . Technol., Vol. 17, No. 7, 1983
Larry P. Breitenbach is α research scientist in the Chemistry Department, Chemical Sciences Laboratory, Research Staff, Ford Motor Company. Breitenbach has been involved in atmospheric chemistry research since 1964. He is a coholder of a patent for a catalyst used in NOx detection equipment. He received his BS degree in chemistry at the University of Michigan and has done graduate work in chemistry and metallurgy at Wayne State Univer sity.
