Carbonyl Products of the Gas Phase Reaction of Ozone with

DGA, Inc., 4526 Telephone Road, Suite 205,. Ventura, California 93003. The gas phase reaction of ozone with alkenes is of critical importance in atmos...
0 downloads 0 Views 221KB Size
Environ. Sci. Technol. 1996, 30, 2036-2044

Carbonyl Products of the Gas Phase Reaction of Ozone with Symmetrical Alkenes ERIC GROSJEAN AND DANIEL GROSJEAN* DGA, Inc., 4526 Telephone Road, Suite 205, Ventura, California 93003

aerosols, which have a significant impact on urban pollution, regional air quality, atmospheric acidity, and global climate (1-5). While the gas phase reaction of ozone with alkenes has been the object of numerous studies (1-34), the reaction mechanism is still poorly understood. The currently believed mechanism involves 1,3-dipolar cycloaddition of ozone at the unsaturated carbon-carbon bond followed by decomposition of the 1,2,3-trioxolane adduct into two carbonyls (hereafter primary carbonyls) and two carbonyl oxide biradicals (1-7, 13-23, 27-31): R1R2C

CR3R4 + O3

R1COR2 + (R3R4COO)* R3COR4 + (R1R2COO)*

The gas phase reaction of ozone with alkenes is of critical importance in atmospheric chemistry. Major uncertainties include the nature and yields of the carbonyl products and the subsequent reactions of the biradicals. In this study, carbonyl products have been identified and their yields measured in experiments involving the gas phase reaction of ozone with the eight symmetrical alkenes ethylene, cis-3-hexene, cis4-octene, trans-4-octene, cis-5-decene, trans-5decene, trans-2,5-dimethyl-3-hexene, and (cis + trans)3,4-dimethyl-3-hexene in purified air. Sufficient cyclohexane was added to scavenge the hydroxyl radical (OH) in order to minimize the reaction of OH with the alkenes and with their carbonyl products. Formation yields (carbonyl formed/ozone reacted) of primary carbonyls were close to the value of 1.0 that is consistent with the simple reaction mechanism: O3 + R1R2CdCR1R2 f R1COR2 + (R1R2COO)*. Carbonyls other than the primary carbonyls R1COR2 were identified as products. Their formation is discussed in terms of subsequent reactions of the R1R2COO biradicals CH3CH2CHOO, CH3(CH2)2CHOO, CH3(CH2)3CHOO, (CH3)2CHCHOO, and C2H5C(CH3)OO. Similarities and differences are discussed for cis and trans isomers and for biradical reactions as a function of the nature and number of the substituents. The results are compared to those for the biradicals H2COO, CH3CHOO, and (CH3)2COO from simpler symmetrical alkenes and contribute to a better understanding of the ozone-alkene reaction under atmospheric conditions.

Introduction The gas phase reaction of ozone with alkenes is of critical importance in atmospheric chemistry and plays a major role in the formation of photochemical oxidants and of * Corresponding author telephone: 1-805-644-0125; fax: 1-805644-0142.

2036

9

ENVIRONMENTAL SCIENCE & TECHNOLOGY / VOL. 30, NO. 6, 1996

(1)

Only limited experimental evidence is available regarding the nature and yields of the primary carbonyl products R1COR2 and R3COR4 and the subsequent reactions of the biradicals (R1R2COO)* and (R3R4COO)*. Complicating the results and their interpretation in previous work is the fact that the hydroxyl radical (OH) forms as a reaction product (5, 6). Under conditions relevant to the atmosphere, OH reacts with alkenes ca. 5 orders of magnitude faster than ozone does (4) and also reacts rapidly with many of the ozone-alkene reaction products including the primary carbonyls that form in reaction 1. Thus, a better understanding of the mechanism of the ozone-alkene reaction can be gained by carrying out experiments that are designed to scavenge OH, thereby minimizing OH-alkene and OHcarbonyl reactions. Several studies of this type, in which sufficient cyclohexane was added to scavenge OH, have been undertaken recently: one involving the measurement of carbonyls and carboxylic acids from C4-C6 alkenes (15) and several involving the measurement of carbonyls from simple alkenes (35), from C5-C10 1-alkenes (6, 36, 37), from unsaturated aliphatic alcohols (38), from unsaturated aliphatic carbonyls and esters (39), and from isoprene (4042). In this work, we have studied symmetrical alkenes, for which reaction 1 reduces to

R1R2CdCR1R2 + O3 f R1COR2 + (R1R2COO)* (2) leading to one primary carbonyl and one biradical. For this reason, symmetrical alkenes provide an excellent opportunity to probe the ozone-alkene reaction mechanism. If the simple mechanism summarized by reaction 2 applies, then the primary carbonyl R1COR2 should be observed to form, and this with a formation yield of 1.0. Other carbonyls, if observed as reaction products, provide information on the nature and magnitude of subsequent reactions of the biradical R1R2COO. These two major features of the ozone-alkene reaction mechanism have received little experimental confirmation at the present time (6, 35-37). We have recently investigated four simple symmetrical alkenes: ethylene, 2-butene (a mixture of ca. 40% cis and 60% trans isomers), trans-3-hexene, and 2,3-dimethyl-2butene (35). For these alkenes, reaction 2 can be written as

S0013-936X(95)00828-5 CCC: $12.00

 1996 American Chemical Society

CH2

CH2 + O3

CH3CH CHCH3 + O3 CH3CH2CH

CHCH2CH3 + O3

HCHO + H2COO

(3)

CH3CHO + CH3CHOO

(4)

CH3CH2CHO + CH3CH2CHOO

(CH3)2C

C(CH3)2 + O3

(5)

CH3COCH3 + (CH3)2COO

(6)

followed by subsequent reactions of the biradicals H2COO, CH3CHOO, CH3CH2CHOO, and (CH3)2COO. In this work, we have re-investigated ethylene for comparison with our earlier work (35) and have studied seven symmetrical alkenes: cis-3-hexene, cis-4-octene, trans-4-octene, cis-5decene, trans-5-decene, trans-2,5-dimethyl-3-hexene, and 3,4-dimethyl-3-hexene (a mixture of the cis and trans isomers). For these alkenes, reaction 2 can be written as shown below for cis- and trans-4-octene (reaction 7), cisand trans-5-decene (reaction 8), trans-2,5-dimethyl-3hexene (reaction 9), and (cis + trans)-3,4-dimethyl-3-hexene (reaction 10), also see reaction 5 above for cis-3-hexene: CH3(CH2)2CH CH(CH2)2CH3 + O3

CH3(CH2)2CHO + (7)

CH3(CH2)2CHOO CH3(CH2)3CH CH(CH2)3CH3 + O3

CH3(CH2)3CHO + (8)

CH3(CH2)3CHOO (CH3)2CHCH CHCH(CH3)2 + O3

(CH3)2CHCHO + (9)

(CH3)2CHCHOO CH3CH2C(CH3)

C(CH3)CH2CH3 + O3

CH3CH2COCH3 + CH3CH2C(CH3)OO

(10)

The symmetrical alkenes R1R2CdCR1R2 studied were selected from considerations regarding the reaction mechanism, see Results and Discussion. The n-alkyl-substituted compounds RCHdCHR were included to study the influence of substituent size from R ) H (ethylene) to R ) n-butyl(cis- and trans-5-decene). These alkenes together with 2-butene (R ) methyl) studied earlier (35) and trans2,5-dimethyl-3-hexene (R ) isopropyl), provide an opportunity to compare biradical reactions that involve H-atom abstraction from primary, secondary, and tertiary C-H bonds. The alkenes 3-hexene, 4-octene, and 5-decene also offer an opportunity to examine similarities and differences between cis- and trans-1,2-disubstituted isomers. The tetrasubstituted alkene 3,4-dimethyl-3-hexene (R1 ) methyl, R2 ) ethyl) was included for comparison with its simpler homologue 2,3-dimethyl-2-butene (R1 ) R2 ) methyl) studied earlier (35) and to provide additional data for comparison of the disubstituted biradicals R1R2COO to the monosubstituted biradicals RCHOO.

Experimental Methods Cyclohexane (Aldrich, stated purity g99.9%) and the alkenes (ethylene and trans-5-decene, Aldrich; all other alkenes, Wiley Organics) were used without further purification. Stated purities were 95% for trans-2,5-dimethyl-3-hexene, 97% for cis-5-decene, 98% for cis-3-hexene and cis-4-octene, 99% for (cis + trans)-3,4-dimethyl-3-hexene, >99% for trans5-decene, >99.5% for ethylene, and 99.8% for trans-4octene. A sample of trans-2,5-dimethyl-3-hexene was analyzed by gas chromatography/electron impact mass spectometry. The total ion chromatogram and the mass spectra (not shown) indicated that the sample contained 91.6% trans-2,5-dimethyl-3-hexene along with 5.2% of the cis isomer and ca. 1.9%, 0.3%, and 0.9% of three other

compounds, one of which was tentatively identified (by matching the compound’s spectrum to the data from a library of mass spectra) as being 3,4-dimethyl-2,4-hexadiene. Similarly, the total ion chromatogram and mass spectra (not shown) indicated that (cis + trans)-3,4dimethyl-3-hexene contained 36.4% of the cis isomer and 63.6% of the trans isomer with no detectable amount of impurities (estimated 0.284 0.572 0.382h 0.272i total 0.654

a From Table 1 and ref 35, standard deviations omitted for clarity. b Formaldehyde from (cis + trans)-2-butene and from 2,3-dimethyl-2-butene; acetaldehyde from cis- and trans-3-hexene; propanal from cis- and trans-4-octene; butanal from cis- and trans-5-decene; acetone from trans-2,5dimethyl-3-hexene; formaldehyde + acetaldehyde from (cis + trans)-3,4-dimethyl-3-hexene. c Hydroxyacetaldehyde and/or glyoxal from (cis + trans)-2-butene; 2-hydroxypropanal and/or methylglyoxal from cis- and trans-3-hexene; 2-hydroxybutanal and/or 2-oxobutanal from cis- and trans4-octene; 2-hydroxypentanal and/or 2-oxopentanal from cis- and trans-5-decene; 2-hydroxy-3-methylpropanal from trans-2,5-dimethyl-3-hexene; hydroxyacetone and/or methylglyoxal from 2,3-dimethyl-2-butene; and (3-hydroxy-2-butanone and/or biacetyl) + (2-hydroxybutanal and/or 2-oxobutanal) from (cis + trans)-3,4-dimethyl-3-hexene. d Mean of results from this study and those from ref 35. e From ref 35. f May be upper limit for actual yield due to co-elution of methylglyoxal-DNPH and system peak (35). g Expected product is (CH3)2C(OH)CHO, which was not measured. h Biacetyl + acetaldehyde, reaction 29 which involves H-atom abstraction from CH group followed by reactions 30-35. i 2-Oxobutanal + formaldehyde, 2 reaction 36 which involves H-atom abstraction from CH3 group, followed by reactions 37-42.

n-butyl) is in our opinion too limited to draw conclusions at the present time. Several other pairs of cis and trans isomers are currently being studied, and the results will serve as a basis for a more detailed analysis of the importance of stereochemistry with respect to the yields of the ozone-alkene reaction products. (C) For all but two of the alkenes studied, cis-3-hexene and cis-4-octene, formation yields of monofunctional carbonyls (reaction 21 followed by reaction 22) are comparable in magnitude to those of hydroxycarbonyls and/or R-dicarbonyls (reactions 18 and/or reaction 19). For cis3-hexene and cis-4-octene, formation yields of monofunctional carbonyls were lower (by a factor of ∼3) than those of hydroxycarbonyls and/or R-dicarbonyls. (D) Formation yields of carbonyls (other than primary carbonyls) are in qualitative agreement with C-H bond strength considerations for reaction 14, the biradical f unsaturated hydroperoxide pathway, which involves Hatom abstraction. For example, carbonyl formation yields for trans-2,5-dimethyl-3-hexene, for which peroxide formation involves H-atom abstraction from a weak tertiary C-H bond, are higher than carbonyl formation yields from those alkenes, e.g., trans-4-octene, for which peroxide formation involves H-atom abstraction from CH2 or CH3 groups. Similarly for (cis + trans)-3,4-dimethyl-3-hexene, the sum of the yields of acetaldehyde and biacetyl is higher than the sum of the yields of formaldehyde and 2-oxobu-

2042

9

ENVIRONMENTAL SCIENCE & TECHNOLOGY / VOL. 30, NO. 6, 1996

tanal by a factor of ca. 1.4, consistent with the hypothesis that, for the disubstituted biradical CH3CH2C(CH3)OO, peroxide formation involving H-atom abstraction from the CH2 group (reaction 29) is easier than peroxide formation involving H-atom abstraction from the CH3 group, reaction 36. Other Minor Carbonyl Products. In addition to the carbonyl products listed in Table 1 and to the unidentified carbonyls listed in Table 2, the following carbonyls were measured in low yields: formaldehyde (0.019 ( 0.002) and butanal (0.0055 ( 0.0002) from cis-3-hexene; acetaldehyde (0.044 ( 0.023) and glyoxal (0.058 ( 0.003) from cis-4-octene; acetaldehyde (0.060 ( 0.020) and glyoxal (0.030 ( 0.002) from trans-4-octene; propanal (0.015 ( 0.002) from cis-5decene; and propanal (0.030 ( 0.004) from trans-5-decene. These carbonyls may be carbonyl impurities, ozone-alkene reaction products of alkene impurities, actual reaction products via pathways other than those discussed in this work, and/or products of the reaction of the alkenes with a small fraction of OH that was not scavenged by cyclohexane. Formation Yields of CO and HO2. From the measured formation yields of the monofunctional carbonyls that are reaction products of the biradicals RCHOO and R1R2COO, it is possible to derive lower limits for the formation yields of the HO2 radical and of carbon monoxide. For monosubstituted biradicals RCHOO, CO and HO2 form in reaction

Scheme 1 ethylene + O3

1.027 ± 0.066 (formaldehyde + H2COO)

(cis + trans)-2-butene + O3

1.150 ± 0.104 (acetaldehyde + CH3CHOO)

trans-3-hexene + O3

1.011 ± 0.049 (propanal + CH3CH2CHOO)

cis-3-hexene + O3

1.022 ± 0.077 (propanal + CH3CH2CHOO)

trans-4-octene + O3

1.145 ± 0.027 (butanal + CH3(CH2)2CHOO)

cis-4-octene + O3

1.206 ± 0.022 (butanal + CH3(CH2)2CHOO)

trans-5-decene + O3

1.093 ± 0.057 (pentanal + CH3(CH2)3CHOO)

cis-5-decene + O3

1.208 ± 0.033 (pentanal + CH3(CH2)3CHOO)

trans-2,5-dimethyl-3-hexene + O3

1.398 ± 0.085 (2-methylpropanal + (CH3)2CHCHOO)

2,3-dimethyl-2-butene + O3

1.006 ± 0.049 (acetone + (CH3)2COO)

(cis + trans)-3,4-dimethyl-3-hexene + O3

1.159 ± 0.064 (2-butanone + C2H5C(CH3)COO)

21 followed by HCO + O2 f CO + HO2, and HO2 also forms in reaction 22. Therefore, for monosubstituted biradicals, the yield of CO is at least equal to that of the monofunctional carbonyl and the yield of HO2 is at least twice that of the monofunctional carbonyl, e.g., the CO and HO2 yields from trans-4-octene are g0.133 and g0.266, respectively, see Table 3. For disubstituted biradicals R1R2COO, CO does not form along with the monofunctional carbonyl (the CH3CO and C2H5CO radicals formed in reaction 34 and 41, respectively, are expected to react with O2 to form RCO3 radicals); the yield of HO2 is at least equal to that of the monofunctional carbonyl, e.g., g0.288 for (CH3)2COO from 2,3-dimethyl-2-butene (Table 3) and g0.406 (sum of reactions 35 and 42) for C2H5C(CH3)OO from (cis + trans)3,4-dimethyl-3-hexene. Under atmospheric conditions, the HO2 radical reacts with NO to form OH + NO2, thus “fueling” photochemical smog processes (1-4). In the absence of NO (this study, also “clean troposphere” conditions), HO2 radicals lead to H2O2 and other products via HO2 + HO2 and HO2 + RO2 reactions (3, 4, 50, 51). Atmospheric Implications. The results obtained in this study provide useful information regarding the mechanism of the gas phase reaction of ozone with alkenes under conditions relevant to the atmosphere. For the eight alkenes studied under conditions that minimize the reaction of OH with the alkenes and with the carbonyl products of the ozone-alkene reaction, the sums of the formation yields of the primary carbonyls are close to the value of 1.0 that is consistent with the simple mechanism: O3 + R1R2Cd CR1R2 f R1COR2 + R1R2COO. Subsequent reactions of the biradicals R1R2COO lead to monofunctional carbonyls and to hydroxycarbonyls and/or R-dicarbonyls whose formation yields vary with the nature, position, and number of the alkyl substituent R1 and R2. For the symmetrical alkenes studied here and those studied earlier (35), the ozone-alkene reactions can be summarized as follows in Scheme 1. According to reaction 2, the measured formation yield of the primary carbonyl is also the formation yield of the corresponding biradical [with the possible exception of (CH3)2CHCHOO as discussed earlier]. Thus, dividing the formation yields of monofunctional carbonyls and of hydroxycarbonyls and/or R-dicarbonyls listed in Table 3 by those of the corresponding primary carbonyls, subsequent reactions of the monosubstituted biradicals can be written as follows:

H2COO f no carbonyls CH3CHOO [from (40% cis + 60% trans)-2-butene] f (0.110 ( 0.019)(HCHO + CO) + (0.220 ( 0.038) HO2 + (0.139 ( 0.016)(CH2OHCHO and/or CHOCHO) CH3CH2CHOO f a(CH3CHO + CO) + 2aHO2 + b(CH3CHOHCHO and/or CH3COCHO), where a ) 0.167 ( 0.009 and b ) 0.139 ( 0.011 for trans-3-hexene and a ) 0.123 ( 0.005 and b ) 0.040 ( 0.006 for cis-3-hexene CH3(CH2)2CHOO f a(CH3CH2CHO + CO) + 2aHO2 + b(CH3CH2CHOHCHO and/or CH3CH2COCHO), where a ) 0.116 ( 0.006 and b ) 0.116 ( 0.008 for trans-4-octene and a ) 0.075 ( 0.005 and b ) 0.022 ( 0.005 for cis-4-octene CH3(CH2)3CHOO f a(CH3(CH2)2CHO + CO) + 2aHO2 + b(CH3(CH2)2CHOHCHO and/or CH3(CH2)2COCHO), where a ) 0.123 ( 0.011 and b ) 0.117 ( 0.012 for trans5-decene and a ) 0.036 ( 0.004 and b ) 0.038 ( 0.003 for cis-5-decene (CH3)2CHCHOO f a((CH3)2CHCHO + CO) + 2aHO2 + b(CH3)2C(OH)CHO, where a ) 0.203 ( 0.041 and b was not measured for trans-2,5-dimethyl-3-hexene Similarly, subsequent reactions of the disubstituted biradicals can be written as follows: (CH3)2COO (from 2,3-dimethyl-2-butene) f 0.286 ( 0.027 (HCHO + HO2) + 0.282 ( 0.017 (CH3COCH2OH and/ or CH3COCHO) C2H5C(CH3)OO f aCH3CHO + bHCHO + (a + b)HO2 + c(CH3CHOHCOCH3 and/or CH3COCOCH3) + d(CH3CH2CHOHCHO and/or CH3CH2COCHO), where a ) 0.228 ( 0.019, b ) 0.123 ( 0.008, c ) 0.102 ( 0.015, and d ) 0.112 ( 0.016 for (cis + trans)-3,4-dimethyl-3-hexene Our results, which could be further simplified to O3 + symmetrical alkene f 1.0 (primary carbonyl + biradical) followed by reactions of the biradicals as given above, may serve as input to update and expand the description of the ozone-alkene reaction in computer kinetic models that are used to describe urban and regional atmospheric photochemistry (1, 3).

Acknowledgments This work has been supported by internal R&D funds, DGA, Inc., Ventura, CA. Dr. Thorsten Hoffmann and Ms. Hali J. Forstner carried out the GC/MS analyses at the California Institute of Technology, Pasadena, CA. Ms. Brenda Brennan prepared the draft and final versions of the manuscript.

VOL. 30, NO. 6, 1996 / ENVIRONMENTAL SCIENCE & TECHNOLOGY

9

2043

Literature Cited (1) National Research Council. Rethinking the ozone problem in urban and regional air pollution; National Academy Press: Washington, DC, 1991. (2) Atkinson, R.; Carter, W. P. L. Chem Rev. 1984, 84, 437-470. (3) Carter, W. P. L. Atmos. Environ. 1990, 24A, 481-518. (4) Atkinson, R. J. Phys. Chem. Ref. Data 1994, Monograph 2, 216 pp. (5) Atkinson, R.; Aschmann, S. M. Environ. Sci. Technol. 1993, 27, 1357-1363. (6) Atkinson, R.; Tuazon, E. C.; Aschmann, S. M. Environ. Sci. Technol. 1995, 29, 1860-1866. (7) Atkinson, R.; Aschmann, S. M.; Arey, J.; Tuazon, E. C. Int. J. Chem. Kinet. 1994, 26, 945-950. (8) Bahta, A.; Simonaitis, R.; Heicklen, J. Int. J. Chem. Kinet. 1984, 16, 1227-1246. (9) Becker, K. H.; Bechara, J.; Brockmann, K. J. Atmos. Environ. 1993, 27A, 57-61. (10) Bennett, P. J.; Harris, S. J.; Kerr, J. A. Int. J. Chem. Kinet. 1987, 19, 609-614. (11) Ga¨b, S.; Hellpointner, E.; Turner, W. V.; Korte, F. Nature 1985, 316, 535-536. (12) Gillies, J. Z.; Gillies, C. W.; Suenram, R. D; Lovas, F. J. J. Am. Chem. Soc. 1988, 110, 7991-7999. (13) Grosjean, D. Environ. Sci. Technol. 1990, 24, 1428-1432. (14) Grosjean, D. Sci. Total Environ. 1984, 37, 195-211. (15) Grosjean, D.; Grosjean, E.; Williams, E. L., II. Environ. Sci. Technol. 1994, 28, 186-196. (16) Grosjean, E.; Grosjean, D. Int. J. Chem. Kinet. 1995, 27, 10451054. (17) Hatakeyama, S.; Akimoto, H. Bull. Chem. Soc. Jpn. 1990, 63, 2701-2703. (18) Hatakeyama, S.; Kobayashi, H.; Akimoto, H. J. Phys. Chem. 1984, 88, 4736-4739. (19) Hatakeyama, S.; Izumi, K.; Fukuyama, T.; Akimoto, H. J. Geophys. Res. 1989, 94, 13,013-13,024. (20) Hatakeyama, S.; Ohno, M.; Weng, J.; Tagaki, H.; Akimoto, H. Environ. Sci. Technol. 1987, 21, 52-57. (21) Hatakeyama, S.; Tanonaka, T.; Weng, J.; Bandow, H.; Takagi, H.; Akimoto, H. Environ. Sci. Technol. 1985, 19, 935-942. (22) Herron, J. T.; Huie, R. E. J. Am. Chem. Soc. 1977, 99, 5430-5435. (23) Herron, J. T.; Huie, R. E. Int. J. Chem. Kinet. 1978, 10, 10191041. (24) Horie, O.; Moortgat, G. K. Chem. Phys. Lett. 1989, 156, 39-46. (25) Horie, O.; Moortgat, G. K. Atmos. Environ. 1991, 25A, 18811896. (26) Horie, O.; Neeb, P.; Limbach, S.; Moortgat, G. K. Geophys. Res. Lett. 1994, 21, 1523-1526. (27) Martinez, R. I.; Herron, J. T. J. Phys. Chem. 1987, 91, 946-953. (28) Martinez, R. I.; Herron, J. T. J. Phys. Chem. 1988, 92, 4644-4648. (29) Martinez, R. I.; Herron, J. T.; Huie, R. E. J. Am. Chem. Soc. 1981, 103, 3807-3820.

2044

9

ENVIRONMENTAL SCIENCE & TECHNOLOGY / VOL. 30, NO. 6, 1996

(30) Niki, H.; Maker, P. D.; Savage, C. M.; Breitenbach, L. P. Environ. Sci. Technol. 1983, 17, 312A-322A. (31) Niki, H.; Maker, P. D.; Savage, C. M; Breitenbach, L. P.; Hurley, M. D. J. Phys. Chem. 1987, 91, 941-946. (32) Nolting, F.; Behnke, W.; Zetzsch, C. J. Atmos. Chem. 1988, 6, 47-59. (33) Treacy, J.; El Hag, M.; O’Farrell, D.; Sidebottom, H. Ber. BunsenGes. Phys. Chem. 1992, 96, 422-427. (34) Zozom, J.; Gillies, C. W; Suenram, R. D.; Lovas, F. J. Chem. Phys. Lett. 1987, 140, 64-70. (35) Grosjean, E.; de Andrade, J. B.; Grosjean, D. Environ. Sci. Technol. 1996, 30, 975-983. (36) Grosjean, E.; Grosjean, D. Environ. Sci. Technol. 1996, 30, 13211327. (37) Grosjean, E.; Grosjean, D.; Seinfeld, J. H. Environ. Sci. Technol. 1996, 30, 1038-1047. (38) Grosjean, D.; Grosjean, E. J. Geophys. Res. 1995, 100, 2281522820. (39) Grosjean, E.; Grosjean, D.; Seinfeld, J. H. Gas phase reaction of ozone with trans-2-hexenyl acetate, ethylvinyl ketone and 6-methyl-5-hepten-2-one. Int. J. Chem. Kinet. 1996, 28, in press. (40) Grosjean, D.; Williams, E. L., II; Grosjean, E. Environ. Sci. Technol. 1993, 27, 830-840. (41) Aschmann, S. M.; Atkinson, R. Environ. Sci. Technol. 1994, 28, 1539-1542. (42) Atkinson, R.; Arey, J.; Aschmann, S. M.; Tuazon, E. C. Res. Chem. Intermed. 1994, 20, 385-394. (43) Grosjean, E.; Grosjean, D. Int. J. Environ. Anal. Chem. 1995, 61, 47-64. (44) Grosjean, E.; Grosjean, D.; Fraser, M. P.; Cass, G. R. An air quality model evaluation data set for organics. 2. C1-C14 carbonyls in Los Angeles air. Environ. Sci. Technol., submitted for publication. (45) Grosjean, E.; Grosjean, D. Int. J. Environ. Anal. Chem. 1995, 61, 343-360. (46) Grosjean, E.; Grosjean, D. Environ. Sci. Technol. 1996, 30, 859863. (47) Bauld, N. L.; Thompson, J. A.; Hudson, C. E.; Bailey, P. S. J. Am. Chem. Soc. 1968, 90, 1822. (48) Bailey, P. S. Ozonation in Organic Chemistry. Vol. I. Olefinic Compounds; Academy Press: New York, 1978; Chapters IV-VII. (49) Bailey, P. S. Ozonation in Organic Chemistry. Vol. II. Non-olefinic compounds; Academic Press: New York, 1982; Chapter XII. (50) Madronich, S.; Calvert, J. G. J. Geophys. Res. 1990, 95, 56975715. (51) Stockwell, W. R. J. Geophys. Res. 1995, 100, 11,695-11,698.

Received for review November 6, 1995. Revised manuscript received January 31, 1996. Accepted February 1, 1996.X ES950828Z X

Abstract published in Advance ACS Abstracts, April 1, 1996.