Experimental and Theoretical Investigations on the Reaction of 1,3

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Experimental and Theoretical Investigations on the Reaction of 1,3-Butadiene With Cl Atom in the Gas Phase Siripina Vijayakumar, and Balla Rajakumar J. Phys. Chem. A, Just Accepted Manuscript • DOI: 10.1021/acs.jpca.6b12227 • Publication Date (Web): 10 Feb 2017 Downloaded from http://pubs.acs.org on February 11, 2017

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The Journal of Physical Chemistry

Experimental and Theoretical Investigations on the Reaction of 1,3-Butadiene with Cl Atom in the Gas Phase S. Vijayakumar and B. Rajakumar* Department of Chemistry, Indian Institute of Technology Madras, Chennai 600036, India. *Address for correspondence: [email protected] http://chem.iitm.ac.in/faculty/rajakumar/ Abstract Temperature dependent rate coefficients for the reaction of Cl atom with 1,3-butadiene were measured over the temperature range of 269-363K relative to its reaction with isoprene and 1pentene. Theoretical calculations were performed for the title reaction using CVT/SCT in combination with CCSD(T)/6-31+G (d,p)//MP2/6-311+G(2df,2p) level of theory, to complement our experimental measurements. The test molecule would survive for one hour in the atmosphere and therefore, it can be considered as a very short lived compound. 1,3-butadience cannot contribute to global warming as it is very short lived. However, a 4ppm of ozone is estimated to be formed by the test molecule, which can be considered to be reasonably significant. 1. Introduction The reactions of unsaturated hydrocarbons with atmospheric oxidizing species (viz. OH and NO3 radicals, Cl atoms and O3 molecules) are highly significant in the Earth’s atmosphere1. These reactions usually lead to the formation of secondary organic aerosols2,3. Among such unsaturated hydrocarbons, 1,3-butadiene is one of the most abundant compound which is

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released into the Earth’s atmosphere via both natural and anthropogenic processes. It is released into the Earth’s atmosphere via several processes such as burning of biomass4, petroleum refining, tobacco burning5, via cooking oils6,7. It is one of the constituents in gasoline and is released into the atmosphere due to incomplete combustion of gasoline and diesel fuels. It is identified as a carcinogenic compound for humans8 as well as rodents9,10. It is widely used in manufacturing of synthetic rubber, includes neoprene, nitrile rubber, polybutadiene, acrylonitrile-butadiene-styrene resin, styrene-butadiene copolymer and nylon 6,6. Styrenebutadiene copolymer is used to make latex, mechanical rubber goods and tires. Latex is used in paints, paper coatings, adhesives, carpet, textile backing and in foam products. According to Clean Air Act, 1995 under California’s air toxic program, 1,3-butadiene was identified as a toxic air pollutant11. California Air Resources Board (ARB) in 1997 has estimated that, approximately 96% annual emissions of 1,3-butadiene are released by motor vehicles. ARB in 1992 stated that 1,3-butadiene is one of the intermediates in oxidation of fuel components such as ethylbenzene, benzene, toluene etc. Naturally 1,3-butadiene is released into the atmosphere as a product of incomplete combustion in forest fires (HSDB, 1995)12. As there are lots of sources of 1,3-butadiene, it is essential to know the fate of this molecule in the Earth’s atmosphere. Lifetimes and global warming potentials which are necessary in understanding its fate in the atmosphere, can be estimated with the measured or computed kinetic parameters of its reaction with the oxidizing species in the Earth’s atmosphere. Cl atoms are one of the most powerful oxidizing agents and therefore, the present study is focused to obtain the kinetic parameters for the reaction of 1,3-butadiene with Cl atoms using both experimental and computational methods.


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Very few groups measured the rate coefficients for the reaction of 1,3-butadiene with Cl atoms using relative rate and absolute methods at room temperature. Ragains and Finlayson-Pitts et al.13 reported the rate coefficient for this reaction as k = (4.2±0.4) ×10-10 cm3molecule-1s-1 at 298K and 760 Torr pressure which was measured using relative rate technique. Notario et al.14 reported the rate coefficient as k = (3.48 ±0.10) ×10-10 cm3molecule-1s-1 at 298K and 15-60 Torr pressure using laser photolysis-resonance fluorescence technique. Even though these two studies are available at room temperature, the temperature dependent rate coefficient data is not reported till date for the title reaction. As far as the reaction of 1,3-butadiene with OH radicals is considered, many studies were reported in the literature15-19 which include temperature dependent studies using varieties of experimental methods and computational studies. In the event of lack of temperature dependent studies on the title reaction, in this paper, we are reporting the temperature dependent rate coefficients measured over the temperature range of 269-363K using relative rate method. To complement the experimental measurements, the rate coefficients for the title reaction were also computed using CVT/SCT over the temperature range of 200-400K in combination with CCSD(T)/6-31+G(d,p)//MP2/6311+G(2df,2p) level of theory. Thermodynamic properties, atmospheric implications and the ozone formation potentials of the test molecule are discussed in this manuscript.



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2. Methodologies 2.1. Experimental Rate coefficients for the reaction of 1,3-butadiene with Cl atom were measured over the temperature range of 269-363K using relative rate method. The complete experimental setup and the details were given in our earlier publications20-22 and only a brief and necessary description is given here. All the experiments were performed in a double walled Pyrex chamber of volume 1250 cm3. The temperature was maintained inside the reaction cell by circulating a heated/cooled fluid in outer jacket and the temperature of the reaction chamber was calibrated using a thermocouple (K-type). The uncertainty in the measurement of the temperature is ±2 K in the studied temperature range. To allow the UV radiation into the reaction chamber, UV fused silica broad band windows (Thorlabs) were employed. Concentrations of the organics were monitored by Gas Chromatograph (GC, Agilent Technologies 7890B) coupled with a Flame Ionization Detector (FID). HP-PLOT/Q, a 30 m × 0.320 mm × 20.0 µm, 19091P-Q04 column was used for the separation of the organics with an optimized flow, pressure and temperature conditions. Cl atoms were produced in situ via photolysis of oxalylchloride (COCl)2 at 254 nm using two UV lamps (Sankyo Denki G8T5, 8 W). Typical concentrations of (COCl)2 used in reaction chamber were in the range of (6-8)×1017 molecules cm-3. Some elementary tests were performed to check for wall losses. The reaction mixture was kept in the absence of light for about six hours and the samples analyzed with GC-FID. No significant decrease in the concentrations of reactants was observed. The reactant and the reference compounds were mixed and photolyzed at 254 nm in the absence of the precursor for Cl atoms to verify the loss of the compounds due to direct photo dissociation and no such thing was observed in the post photolysis analyses. The


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reaction mixture (reactant, reference compounds and the Cl atom precursor) was photolyzed for a period of 3-4 minutes and after photolysis, the reaction mixture was allowed undisturbed for about 20 minutes to get uniform concentration throughout the reaction chamber. The samples were withdrawn using a gas tight syringe for the analyses in GC. The rate coefficients were determined using standard relative rate expression, given below. In this method, the rate of decay of sample due to its reaction with Cl atoms is compared with that of a reference compound whose rate coefficient is already known for its reaction with Cl atoms. ,

, =

,

………

(1)

where, [1,3-butadiene]0, [1,3-butadiene]t, [reference]0 and [reference]t are the concentrations of the sample and reference compounds at time ‘0’ and ‘t’ respectively, k1,3-butadiene and kreference are the rate coefficients for their reactions with Cl atoms. Thus, the plot of ln([1,3-butadiene]0/[1,3butadiene]t) versus ln([reference]0/[reference]t) should be a straight line with zero intercept, in the event of the absence of any secondary reactions. The rate coefficient for the reaction of interest can be calculated using the slope [k1,3-butadiene/kreference] obtained and the available rate coefficient for the reference reaction at a given temperature. Chemicals: 1,3-butadiene (purity 99.5%, Praxair), oxalylchloride (purity 98%, Spectrochem), isoprene (purity 99%, Aldrich), 1-pentene (purity ≥98.5%, Aldrich), nitrogen (99.995%, Bhuruka gases, India), oxygen (98%, Bhuruka gases, India). Before using isoprene, 1-pentene and oxalylchloride were subjected to repeated freeze-pump-thaw cycles.



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2.2. Computational The rate coefficients for the title reaction were also calculated using Canonical Variational Transition State Theory (CVT) with Small Curvature Tunneling (SCT) in combination with CCSD(T)/6-31+G(d,p)//MP2/6-311+G(2df, 2p) level of theory. All the geometries of reactants (1,3-butadiene and Cl), pre-reactive complexes, transition states and products were optimized with the second order MP2 (Møller-Plesset)23 level of theory using the Pople’s basis set24 6-311+G(2df,2p). All the electronic structure calculations were carried out using Gaussian 09 program suite. The Intrinsic Reaction Coordinates (IRCs) calculations were carried out at the same level of theory to check if all the transition states are connected to reactants and products via distinguishable reaction paths25-27. Single point energies of all the stationary points (reactants, pre-reactive complexes, transition states and products) were calculated using Couple-Cluster with Single, Double and Triple excitation (CCSD(T)) theory with 6-31+G(d,p) basis sets. Dual level calculations were known28,29 to calculate accurate kinetic parameters and therefore were used in this reaction. The energies obtained at CCSD(T)/631+G(d,p)//MP2/6-311+ G(2df,2p) level of theory were used to calculate the rate coefficients for the title reaction. 2.2.1. Kinetics The temperature dependent rate coefficients for the reaction of 1,3-butadiene with Cl atoms were calculated using CVT with SCT30. , ! = "

#$ & '( ,)! %

ф+ !

/012 3!

!exp

#$

4/ ! = 5673 , ! = ,

! …… (2)

4/ !


…... (3)

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where kcvt is the rate coefficient from CVT and kGT is the generalized rate coefficient. VMEP(s) is potential energy of generalized TS at‘s’. σ is the reaction path degeneracy, h= Planck’s constant, kB is the Boltzmann constant, T= temperature (in Kelvin), фR and QGT are the partition functions of a generalized reactant at ‘s’ and transition state respectively. sCVT is the reaction coordinate of the canonical variational transition state dividing surface. The tunneling corrected rate coefficients (kCVT/SCT) were obtained by multiplying kCVT and a temperature dependent transmission coefficient Ƙ4//)4 (T). The two spin−orbit (SO) states 2P3/2 (lowest) and 2P1/2 of Cl atom having degeneracies of 4 and 2 respectively and separated by 882.3515 cm−1 were included in the Cl atom electronic partition function calculations 31. k 4//)4 ! = Ƙ4//)4 !k 4/ !

…… (4)

3. RESULTS AND DISCUSSION 3.1. Experimental The temperature dependent rate coefficients for the reaction of Cl atoms with 1,3butadiene were measured experimentally over the temperature range of 269-363 K using isoprene and 1-pentene as reference compounds. Although the rate coefficients of Cl atom reactions with unsaturated hydrocarbons at room temperature have reported by several groups3235

, there are only two temperature dependent rate coefficients (Cl + isoprene36 and Cl + 1-

pentene37) available whose rate coefficients are close to the rate coefficients of the title reaction at the temperatures across the study. The rate coefficients measured relative to isoprene were observed to be very close to the reported rate coefficients. However, the rate coefficients measured relative to 1-pentene over the studied temperature range (269-363K) were found to be overestimated when compared with those available in the literature. Bedjanian et al.36 carried out 7 ACS Paragon Plus Environment


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the reaction in 0.2 L Pyrex chamber and used the discharge-flow mass spectrometric method with Cl + Br2 as the reference reaction and reported the temperature dependent rate coefficient as k233-320K=(6.7±2.0)×10-11exp[(485±85)/T] cm3molecule-1s-1 with a room temperature (298K) rate coefficient of (3.41±0.50)×10-10 cm3molecule-1s-1. The error associated with the rate coefficient reported by Bedjanian et al.36 was 15%. Coquet et al.37 studied the reaction of Cl atoms with 1pentene in 3L Pyrex flask equipped with magnetic stirrer and GC-FID with reference to hexane + Cl reaction and reported the temperature dependent rate coefficient as k283-323K= (4.0±2.2)×10-11 exp[(733±288)/T] cm3 molecule-1s-1 with a room temperature rate coefficient of (4.69±0.08)×1010

cm3molecule-1s-1. The error associated with the Coquet et al.37 was reported to be 2%. In the

present experimentation, the reactions were carried out with two references in back to back mode. Therefore, any systematic errors should be similar in both the cases. Measurement of physical parameters such as temperature and pressure were also carried out following the same procedures in both the cases. Identical analytical procedures were followed while carrying out the reaction with both the references. Therefore, we are confident that the systematic errors, if any would have been almost identical in both the cases. In any case, the rate coefficients measured using isoprene [(3.31±0.48)×10-10 cm3molecule-1s-1] were found to be close to the one reported by Notario et al.14 [(3.48±0.10)×10-10 cm3molecule-1s-1] and also close to the rate coefficient obtained in the present computational investigations (3.31×10-10 cm3molecule-1s-1), vide infra. Therefore, the rate coefficients measured using isoprene as reference compound were used to fit the Arrhenius equation by using Linear Least Squares methods. Thus deduced temperature dependent rate coefficient for the title reaction is kExperimental (269-363K) = (1.05±0.19) ×10-10 exp [(332±56)/T] cm3 molecule-1s-1. Slight negative temperature dependence was observed over the range of 269-363K. The negative temperature dependence is mainly due to the addition


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of Cl atom across the double bonds. This would lead to the formation of pre reactive complexes, which are more stabilized, vide infra. The Arrhenius plot is shown in Figure 1. The rate coefficients obtained using 1-pentene as reference compound were not used to deduce the temperature dependence of the studied reaction, as they were found to be overestimated. The rate coefficients were measured following the above described procedure at 269, 285, 298, 310, 330, 350 and 363K and are given in Table 1. To evaluate the reproducibility of the results, experiments were repeated at least three times at every temperature. Slopes and errors were obtained from the linear least-square fitting of the experimental data and are depicted in Table 1. Typical relative rate plots for the reaction of 1,3-butadiene with Cl atoms are shown in Figure 2. 3.2. Electronic structures and energetics All the optimized geometries of reactants, pre-reactive complexes, transition states and products obtained at MP2/6-311+G(2df,2p) level of theory are shown in Figure 3. The prereactive complexes for the reactions going through submerged transition states (TS1a and TS2a) were also identified and optimized. The optimized parameters for the reactants, pre-reactive complexes, transition states and products are given in Tables S-1-1 to S-1-11 of the supporting information. The vibrational frequencies of all the geometries were optimized at the same level of theory and are given in Tables S-2-1 to S-2-2 of the supporting information. The potential energy level diagram obtained at CCSD(T)/6-31+G(d,p)//MP2/6-311+G(2df,2p) level of theory at 298K is shown in Figure 4.



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In 1,3-butadiene, there are ten reaction sites in total including four addition channels (via TSs TS1a, TS2a, TS3a and TS4a) and six abstraction channels (via TSs TS1, TS2, TS3, TS4, TS5 and TS6), as shown above. Addition channels are represented by adding suffix ‘a’. Since 1,3-butadiene has C2h point group symmetry, the addition reaction sites, two terminal carbons (TS1a and TS4a) and two middle carbons (TS2a and TS3a) are identical. The abstraction reaction sites, terminal hydrogen atom (TS1) on ‘CH2=’ and another terminal hydrogen atom (TS6) are identical. Similarly TS2 and TS5 are identical. Hydrogen atoms (TS3 and TS4) which are located on middle carbons are also identical. Finally, the ten transition states are reduced to five independent channels (two addition channels (TS1a & TS2a) and three abstraction channels (TS1, TS2 and TS3). Cl atom addition to the double bond of the terminal carbon and at the second carbon leads to the formation of products P1a and P2a respectively. Hydrogen abstraction from two terminal and the middle carbons leads to the formation of products P1, P2 and P3 respectively. In case of hydrogen abstraction, in transition states the breaking-C-H bond lengths are stretched up to 38%, 40% and 25% for TS1, TS2 and TS3 respectively when compared with respective normal-C-H bond lengths in 1,3-butadiene. To predict the feasibility and spontaneity of the reaction, the standard Gibbs’s free energies (∆Go), standard enthalpies (∆Ho) and entropies of the transition states were calculated at 298K and given in Table 2. The addition channel (TS1a) was found to be highly exothermic (∆Ho=-23.65 kcal./mole at 298K) and abstraction 10 ACS Paragon Plus Environment

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channel (TS1) was found to be highly endothermic (∆Ho=24.3 kcal./mol at 298K). TS1a (-2.93 kcal./mol at 298K) and TS2a (-0.12 kcal./mol at 298K) are submerged transition states and therefore they contribute maximum to the overall reaction. 3.3. Rate coefficients Rate coefficients for the title reaction were calculated over the temperature range of 200400K with an interval of 25K are tabulated in Table 3. The rate coefficients obtained at CCSD(T)/6-31+G(d,p)//MP2/6-311+G(2df,2p) level of theory are in very good agreement with the experimentally measured rate coefficients at room temperature and reasonably in good agreement at temperatures other than room temperature. The good agreement at the room temperature may be because of cancellation of errors. And therefore, this particular combination of the theory may be considered as a good choice for the present system only. The computed rate coefficients were used to derive the temperature dependent Arrhenius expression, which is kTheory (200-400K)

= (4.12±0.3)×10-12 exp[(1312±20)/T] cm3molecule-1s-1. It should be noted here that, the

rate coefficients for the reaction below 275 K are touching the gas kinetics limit. This kind of behavior is expected in case of the radical – radical reactions. One justification that can be provided here is, the presence of Cl atom/radical in the title reaction. In addition, the reaction is totally governed by the addition of Cl atom at the two double bonds present in the substrate. Both the reaction channels are exothermic. Also, these two channels are feasible both kinetically (because of the submerged transition states) and thermodynamically. As the reaction is dominant and proceed via negative transition states, the rate of reaction increases with the decrease in temperature. This is an added advantage for the reaction to be very fast. All these would probably favor the reaction at low temperatures to the largest possible extent.



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In the present investigation, the experimentally measured rate coefficient kExperimental= (3.31±0.48)×10-10 cm3molecule-1s-1 is in excellent agreement with computationally calculated rate coefficient kTheoretical= 3.31×10-10 cm3 molecule-1s-1 at 298 K. Also, both experimentally measured and theoretically computed rate coefficients are in good agreement with the reported rate coefficient by Notario et al.14, k = (3.48±0.10) ×10-10 cm3molecule-1s-1 at 298K and in the pressure range of 15-60 Torr pressure. However, the rate coefficient reported by Ragains et al.13, k = (4.27±0.40)×10-10 cm3molecule-1s-1 at 298K and 1 atm. pressure is not in good agreement with the one obtained in this study. This is mainly because of their experimental conditions and uncertainties associated with rate coefficients of reference compound (n-butane) used in their study, which was different from the present study (isoprene). Notario et al.,14 measured the rate coefficient for the title reaction using the laser photolysis-resonance fluorescence technique at 298K and in pressure range of 15-60 Torr whereas Ragains et al.,13 measured the rate coefficient using relative rate technique with reference to n-butane at 298K and at 760Torr pressure. Experimentally measured rate coefficients have shown slight negative temperature dependence and theoretically calculated rate coefficients have shown strong negative temperature dependence. Probably this is due to uncertainties associated with the submerged transition states and theoretically calculated pre-exponential factors. Here it should be noted that the uncertainties in the calculated energies of adducts and transition states can critically effect the calculated rate coefficients (Lynch and Truhlar et al.38). On the other hand, the pre-exponential factor depends on how best the partition functions of reactants and transition states are estimated which in turn depends on the vibrational frequencies obtained in the calculations. As the rate coefficient at a given temperature is the combination of both the pre-exponential factor and the activation


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energy, the difference can be attributed to the accuracy with which both these factors are determined. To understand the mechanism of Cl atom reactions with butadienes, series of butadienes were studied in our laboratory. In our earlier study17, the reported rate coefficients for the reactions of Cl atoms with 2-methyl-1,3-butadiene and 2,3-dimethyl-1,3-butadiene are 4.67×1010

cm3molecule-1s-1 and 4.70×10-10 cm3molecule-1s-1 respectively. In present investigation, the

obtained rate coefficient for the reaction of Cl atoms with 1,3-butadiene is 3.31×10-10 cm3molecule-1s-1. There is an increase in rate coefficient from 1,3-butadiene to 2,3-dimethyl-1,3butadiene. The same trend was observed by Notario et al.,14 for the reactions of series of butadienes with Cl atoms and reported to be 3.48×10-10, 3.61×10-10, and 3.63×10-10 for 1,3butadiene, 2-methyl-1,3-butadiene and 2,3-dimethyl-1,3-butadiene respectively. The increase in these rate coefficients is due to the increase in the available reaction sites (3 more H atoms) and reaction may happen via direct hydrogen abstraction from methyl group. A similar phenomenon was observed by Atkinson et al.,15 and Ohta et al.,16 where they have reported the rate coefficients for the reactions of OH radicals with 1,3-butadiene, 2-methyl-1,3-butadiene and 2,3dimethyl-1,3-butadiene and observed gradual increase in rate coefficients from 1,3-butadiene to 2,3-dimethyl-1,3-butadiene. In case of NO3 radicals reactions, Wayne et al.,39 observed the increment in the rate coefficient from 1,3-butadiene to 2,3-dimethyl-1,3-butadiene due to increase in number of methyl groups. Essentially, the number of reaction sites increases with the addition of methyl groups and therefore, the reaction goes faster. The reaction of unsaturated hydrocarbons with Cl atoms proceeds primarily via addition reactions13. In our theoretical investigation, we also found that the Cl atom addition channels play major role rather than hydrogen abstraction channels. The contribution of the reactions going through addition via 13 ACS Paragon Plus Environment


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transition states TS1a+TS4a (49% each) and TS2a+TS3a (1% each) towards the global rate coefficient are 98% and 2% respectively. However, the contribution of abstraction channels seems to be negligible. Cl atom addition to the double bond at terminal carbon (channel TS1a/TS4a) seems to be major reaction as it contributes about 98% to the total rate coefficient which shows that the Cl atom is preferentially added at the terminal carbon. This is due to the formation of secondary radical which is in conjugation with the other double bonds in 1,3butadiene. Therefore, it gains more stability compared to the primary radical which is generated by Cl atom addition at the second carbon (TS2a/TS3a) which contributes only 2 % to the total rate coefficient. The reaction of Cl atom with 1,3-butadiene via the transition state TS1a/TS4a leads to the formation of 4-chlorocrotonaldehyde and chloromethyl vinyl ketone which is in consistence with the findings reported by Weihong et al.40 Hydrogen abstraction seems to be negligible as per our computational calculations which is in agreement with the observations made by Ezell et al.32 and Walavalkar et al.41 In case of reaction of Cl atom with propene, the contribution of the abstraction of hydrogen atoms is significant, as the number of reaction sites at allylic carbon (two) are greater than those in 1,3-butadiene (zero). Lee et al.,42 estimated the allylic hydrogen abstraction (14%) in propene-chlorine reaction at 3000 Torr total pressure. Kaiser et al.,33 estimated hydrogen abstraction (9%) for Cl–propene reaction at 700 Torr which depends on the relative yield of the products. Both these studies are in consistence with our recent findings on hydrogen abstraction reactions of 1-heptene with Cl atoms, which takes place more favorably at allylic hydrogens when compared with olefinic hydrogens43. To have a clear idea on the trends of the reactions of Cl atoms, OH and NO3 radicals with n-butane, 1-butene, 1,3-butadiene, 2-methyl-1,3-utadiene and 2,3-dimethyl-1,3-butadiene, the reported rate coefficients and the measured ones in the present study at 298 K are tabulated in 14 ACS Paragon Plus Environment

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Table 4. It is very obvious from this Table that, there is systematic increase in the rate coefficients for the reactions of Cl atoms with butane34 through 2,3-dimethyl-1,3-butadiene from 1.94×10-10 cm3molecule-1s-1 to 4.7×10-10 cm3molecule-1s-1. A similar trend is observed in case of the reaction of OH radicals15 from 0.24×10-11 cm3molecule-1s-1 to 12.2×10-11 cm3molecule-1s-1. In case of the reactions of NO3 radicals15, the increase is very drastic from 4.59×10-17 cm3molecule1 -1

s to 14.1×10-13cm3molecule-1s-1. Therefore, it is very clear that butadienes are more reactive

than the butenes and further, butenes are more reactive than butanes. This is due to the increase in unsaturation i.e., the ᴨ-electron system which is present in double bond of the butadienes makes them more reactive than the corresponding alkanes. This reactivity trend shows that more preferential electrophilic addition mechanism rather than hydrogen abstraction for OH radicals, Cl atoms and NO3 radicals reactions. Moreover, the additions of Cl atoms, OH and NO3 radicals have the lower activation energy than the abstraction of hydrogen atom. Hence, addition channels are more dominant in the reactions of double bonded molecules with all the atmospheric oxidants (Cl atoms, OH and NO3 radicals). 4. Atmospheric implications The atmospheric lifetime of a molecule in the Earth’s atmosphere depends on the rates at which it reacts with the oxidizing species such as OH radicals, Cl atoms, NO3 radicals and O3 molecules. Therefore, in the present study the cumulative atmospheric lifetime of 1,3-butadiene was estimated with respect to oxidizing agents such as Cl atoms, OH and NO3 radicals and O3 molecules using the following equation ;

Experimental and Theoretical Investigations on the Reaction of 1,3

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