Primary Reaction Channels Research Articles

Competing isomeric product channels in the 193 nm photodissociation of 2-chloropropene and in the unimolecular dissociation of the 2-propenyl radical

This paper presents product translational energy spectroscopy measurements of the primary photofragmentation channels of 2-chloropropene excited at 193 nm and of the unimolecular dissociation of the 2-propenyl radical. Tunable vacuum ultraviolet (VUV) photoionization of the products allows us to distinguish between the various product isomers formed in these processes. The data show evidence for three significant primary reaction channels in the dissociation of 2-chloropropene: An excited-state C–Cl fission channel producing fast Cl atoms, a C–Cl fission channel producing slow Cl atoms, and HCl elimination. A minor C–CH3 fission channel contributes as well. The measured branching of the major primary product channels is: [fast C–Cl]:[slow C–Cl]:[HCl elimination]=62%:23%:15%. The experiments also allow us to resolve selectively the product branching between the unimolecular dissociation channels of the 2-propenyl radical, a high energy C3H5 isomer; we measure how the branching ratio between the two competing C–H fission channels changes as a function of the radical’s internal energy. The data resolve the competition between the unimolecular H+allene and H+propyne product channels from the radical with internal energies from 0 to 18 kcal/mol above the H+propyne barrier. We find that the barrier to H+allene formation from this high-energy C3H5 radical is higher than the barrier to H+propyne formation, in agreement with recent theoretical calculations but in sharp contrast to that predicted for the most stable C3H5 isomer, the allyl radical. The experiments demonstrate a general technique for selectively forming a particular CnHm isomer dispersed by internal energy due to the primary photolysis, thus allowing us to determine the branching between unimolecular dissociation channels as a function of the selected radical isomer’s internal energy.

Reactions of actinide ions with ethylene oxide.

Naked and oxo-ligated actinide (An) monopositive ions were reacted with ethylene oxide, cyclo-C(2)H(4)O (EtO). Along with An = U, Np, Pu and Am, ions of two lanthanide (Ln) elements, Ln = Tb and Tm, were studied for comparison. Metal and metal oxide ions, M(+), MO(+) and MO(2)(+), were generated by laser ablation and immediately reacted with EtO. Unreacted and product ions were detected by time-of-flight mass spectrometry. It was apparent that the overall reaction cross-sections decreased in the order U(+) > or = Np(+) > Pu(+) > Am(+). A primary reaction channel for each studied metal was the formation of MO(+) from M(+), in accord with the expected exothermicity of oxygen abstraction from EtO. For U, Np and Pu, the dioxides were also major products, indicating OAn(+)--O dissociation energies of at least 350 kJ mol(-1), the energy required for O-atom abstraction from EtO. For Am, Tb and Tm, the dioxides were only very minor products, reflecting the stabilities of the trivalent states and resistance to oxidation to higher valence states; the structures/bonding in these MO(2)(+) are intriguing given that the formal pentavalent bonding state is effectively unattainable. It was demonstrated that EtO, unlike more thermochemically favorable but kinetically restricted O-donors, is effective at achieving facile oxidation of actinide metal ions to the monoxide, and to the dioxide if the second O-abstraction reaction is exothermic. Several intriguing minor products were also identified, most of which incorporate metal--oxygen bonding and are attributed to the oxophilicity of the f-block elements; the contrast to the behavior of first-row d-block transition elements is striking in this regard. Particularly noteworthy was the formation of MH(4)(+) (and MOH(4)(+)), evidently via abstraction of all four H atoms from a single C(2)H(4)O molecule; the structures/bonding in these novel 'hydride' species are indeterminate and warrant further attention.

Gas-Phase Chemistry of Curium: Reactions of Cm+ and CmO+ with Alkenes, Acetonitrile, and Hexafluoropropene

The metal ions, Cm+, U+, and Tb+, and their oxides, MO+, were reacted in the gas phase with alkenes, acetonitrile, and hexafluoropropene. Product compositions and abundances provide a survey of essential aspects of the gas-phase chemistry of the curium cation, now the heaviest element for which such systematic studies have been carried out (U and Tb were included to provide comparisons). Of particular interest is the difference in behavior between the 4f lanthanide and 5f actinide series and variations in chemistry across the actinide series. The primary emphasis was on reactions with alkenes, particularly dehydrogenation, as indicative of the ability of a M+ to activate C−H bonds (the extent of C−C activation was generally in parallel with that of C−H activation). With acetonitrile and all of the alkenes (except ethene), the three M+ ions induced dehydrogenation. Variations were evident for the different reactant substrates, but the overall qualitative ordering of dehydrogenation efficiency was U+ > Tb+ > Cm+. This order is consistent with the variation in electronic promotion energies (PE) required to provide two spin-unpaired, non-f valence electrons at the M+, i.e., a [Rg]fn-2d1s1 configuration (“Rg” = Xe for the lanthanides and Rn for the actinides), to enable its insertion into a C−H bond. The reduced reactivity of Cm+ relative to U+ and Tb+ suggests that the closed-shell 7s2 electrons of ground Cm+ (8S [Rn]5f7s2) are ineffective in enabling C−H activation and that promotion to the 10D [Rn]5f76d17s1 configuration is prerequisite. The PE[Cm+] (48 kJ mol-1) is only slightly greater than PE[Tb+] (39 kJ mol-1) and the significantly greater reactivity of Tb+ vs Cm+ may reflect that the transition to the prepared “divalent” state (d1s1) is parity forbidden for Cm+. The three MO+ were substantially less reactive than the naked M+ but were comparably reactive to one another, consistent with a multicentered activation process, which is less efficient than direct cleavage of a C−H bond by M+ insertion. With hexafluoropropene, the primary reaction channel was F abstraction and the discrepant reactivities reflected the propensity for U to oxidize to higher valence states compared to Cm or Tb. The terminal MFn+ were CmIIIF2+, TbIIIF2+, and UIVF4+, and among the MO+, only UO+ induced F abstraction, producing UOFn+ with n = 1−3.

The influence of local electronic character and nonadiabaticity in the photodissociation of nitric acid at 193 nm

The dissociation of nitric acid upon πnb,O→πNO2* excitation at 193 nm has been studied in a crossed laser-molecular beam apparatus. The primary reaction channels are OH+NO2 and O+HONO. We measure the branching ratio between these two competing processes and determine (OH+NO2)/(O+HONO)=0.50±0.05. Our experiments provide evidence of a minor O+HONO pathway, which we assign to O(3P) and HONO in its lowest triplet state. The dominant pathway correlates to O(1D)+HONO(X 1A′). The translational energy distributions reveal two distinct pathways for the OH+NO2 channel. One pathway produces stable NO2 fragments in the 1 2B2 electronic state. The second pathway produces unstable NO2 fragments which undergo secondary dissociation to NO+O. We examine the influence of nonadiabaticity along the OH+NO2 reaction coordinate in order to explain the significant branching to this other channel. Finally, we introduce a new method for generating correlation diagrams for systems with electronic transitions localized on one moiety, in which we restrict the changes allowed in remote molecular orbitals along the reaction coordinate. Analysis of previously measured X+NO2 photofragment pathways in nitromethane and methyl nitrate provides further support for using a restricted correlation diagram to predict the adiabatic and nonadiabatic product channels.

The reaction between N(4S) and C2H3: Rate constant and primary reaction channels

The rate constant and the product branching ratios have been determined at T=298 K for the reaction between ground state atomic nitrogen (4S) and the vinyl radical (C2H3) at a nominal pressure of 1 Torr He. The kinetic technique employed was discharge-flow coupled to a collision-free sampling mass spectrometer. The rate constant was determined by monitoring the decay of the vinyl radical in the presence of excess [N], yielding a value for k(N+C2H3) of (7.7±2.9)×10−11 cm3 molecule−1 s−1. Three primary reaction channels have been experimentally observed: N+C2H3→C2H2+NH (1a), C2H2N+H (1b), and C2H3N (1c). The lowest energy isomers of the C2H2N radical and the C2H3N adduct molecule are CH2CN and CH3CN, respectively and their identification as products of the reaction is consistent with experimental results. Contributions from the higher energy isomers CH2NC or cyc-C2H2N in channel (1b) and CH3NC or H2C=C=NH in channel (1c) are not consistent with the experimental results and can be ruled out. Contribution from other higher energy isomers such as the radicals HC–CH=N, HC=C=NH and H2C=C=N in channel (1b) and the adduct species vinyl nitrene and 2H-azirine in channel (1c) cannot be ruled out in the absence of knowledge of heats of formation of the radical species and ionization energies for both the radical and adduct species. The following branching ratios were determined at T=298 K: Γ1a=0.16, Γ1c=0.04. No other potential products were detected. It can therefore be inferred that channel (1b) accounts for most if not all of the remaining products, i.e., Γ1b=0.80. The magnitude of the rate constant and the nature of the observed products for N+C2H3 are compared with those for the reactions N+CH3 and N+C2H5. The formation of the adduct molecule is considered in terms of initial formation of vinyl nitrene or 2H-azirine followed by a series of ring openings, ring closings, and an H atom transfer to yield the lowest energy isomer acetonitrile, CH3CN. The possible role of the N+C2H3 reaction in the atmospheric chemistry of Titan, Neptune, and Triton is briefly considered.

Primary Reaction Channels and Kinetics of the Thermal Decomposition of Phenylsilane

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPrimary Reaction Channels and Kinetics of the Thermal Decomposition of PhenylsilaneH. E. O'Neal, M. A. Ring, D. Kim, and K. D. KingCite this: J. Phys. Chem. 1995, 99, 23, 9397–9402Publication Date (Print):June 1, 1995Publication History Published online1 May 2002Published inissue 1 June 1995https://doi.org/10.1021/j100023a015RIGHTS & PERMISSIONSArticle Views177Altmetric-Citations6LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (649 KB) Get e-Alerts

The photodissociation of toluene studied by forward photofragment translational spectroscopy

The translational energies of different fragments produced in laser induced unimolecular reactions are investigated in a molecular beam experiment. The time-of-flight of the photoproducts is measured in the forward direction with a mass spectrometer. By operating the ion source at low electron impact energies it is possible to nearly eliminate fragmentation and observe the nascent products at their parent mass. With this technique the primary and secondary reaction channels can be identified and branching ratios and product translational energy distribution down to small kinetic energies can be measured. The method is illustrated in a study of the photodissociation of toluene (methylbenzene) at three excitation energies (Eex=51 590, 52 240, and 63 240 cm−1). From the measured product time-of-flight spectra the branching ratio as well as the translational energy distributions of the product molecules benzyl+H and phenyl+CH3 in the two reaction channels were determined. The measured product energy distributions are compared with RRK (Rice–Ramsperger–Kassel) and SACM (statistic adiabatic channel model) statistical theories. The experimental results agree very well with the SACM theory for the phenyl, but not for the benzyl products. This is attributed to a barrier in the exit channel for the latter product.

Photodissociation of 2-bromoethanol and 2-chloroethanol at 193 nm

2-Bromoethanol and 2-chloroethanol were photodissociated in a molecular beam at 193 nm. Only one primary reaction channel was observed, elimination of the halogen atom, with an average translational energy release of 33 kcal/mol. In the case of 2-bromoethanol, some of the C2 H4 OH partner fragment survived and some underwent secondary dissociation to produce C2 H4 and OH. The surviving C2 H4 OH contained up to 43 kcal/mol of internal energy, far more than the expected C2 H4 -OH bond energy of ∼28 kcal/mol. The initial C–Br recoil occurs with a large exit impact parameter and leaves most of the internal energy in C2 H4 OH rotation, creating rotationally metastable fragments. The angular distributions of the secondary C2 H4 and OH products were strongly forward–backward peaked with respect to the primary (C2 H4 OH) velocity vector, consistent with the decay of a long-lived complex in which the total angular momentum is perpendicular to the velocity vector and mainly carried away as orbital angular momentum. This effect is analogous to that observed in the decay of similar long-lived complexes in crossed molecular beam experiments.

Crossed molecular beam study of the reaction O(3P)+C2H4

The reaction between ground state atomic oxygen and ethylene was studied under single collision conditions using the crossed molecular beam method. At an average collision energy of about 6 kcal/mol, the two major primary reaction channels are (a) the formation of CH3 and CHO and (b) the formation of C2H3O and H. Product angular distributions and time-of-flight spectra were measured and the translational energy release was determined for each channel. The observed results and calculated potential energy surfaces suggest that after the addition of O(3P) to ethylene forming a triplet diradical, channel (a) occurs by way of intersystem crossing to the singlet state, 1,2-H migration and subsequent C–C bond rupture, whereas channel (b) proceeds mostly through the direct dissociation of the intermediate triplet diradical, except for a small contribution from H atom elimination of the singlet acetaldehyde intermediate.

Crossed molecular beam study of the reaction O(3P)+C2H2

The reaction between ground state atomic oxygen and acetylene was studied using the crossed molecular beam method with an average collision energy of 6 kcal/mol. The two major primary reaction channels are (a) formation of CH2 and CO and (b) formation of HCCO and H. Product angular distributions and time-of-flight spectra were measured and the translational energy release was determined for each channel. The reaction proceeds primarily on the triplet surface through a long-lived intermediate. For both channels the translational energy distributions were found to peak at about 30% of the total available energy, indicating the existence of an exit channel barrier in each case. The branching ratio between channel (a) and (b) was found to be 1.4±0.5.

ChemInform Abstract: Very Low Pressure Pyrolysis (VLPP) of Methyl‐ and Ethynyl Cyclopentanes and Cyclohexanes

Studies of the kinetics of thermal unimolecular decomposition of methylcyclopentane, methylcyclohexane, ethynylcyclopentane, and ethynylcyclohexane have been carried out at temperatures in the range 861–1218 K using the technique of very low-pressure pyrolysis (VLPP). Multiple reaction pathways and secondary decomposition of primary products results in a complex array of reaction products. VLPP rate data (fall-off regime) were obtained for the overall decompositions and interpreted via the application of RRKM theory. The data for methylcyclopentane and methylcyclohexane were interpreted in terms of ring-opening bond fission pathways and bond fission to methyl and cycloalkyl radicals. By selecting Arrhenius parameters consistent with the analogous pathways in open-chain alkanes, a good fit to the overall decomposition is obtained. The data for ethynylcyclopentane and ethynylcyclohexane were interpreted in terms of ring-opening bond fission and alkyne to allene isomerization. The A factors for ring opening were based on known values for C-C fission in open-chain alkynes and the Arrhenius parameters for isomerization were chosen to be consistent with previously reported alkyne to allene isomerizations. The VLPP data are consistent with the following high-pressure rate expressions (at = 1100 K) for the dominant primary reaction channel of ring opening adjacent to the substitutent group: where θ = 2.303RT kJ mol−. Comparison of the activation energies for the ethynyl-cycloalkanes with those for the methyl-cycloalkanes shows that the effect of the ethynyl substituent is consistent with the propargyl resonance energy. This evidence supports the assumption of a biradical mechanism for ring opening in these cycloalkanes.

Very low‐pressure pyrolysis (VLPP) of methyl‐ and ethynyl‐cyclopentanes and cyclohexanes

AbstractStudies of the kinetics of thermal unimolecular decomposition of methylcyclopentane, methylcyclohexane, ethynylcyclopentane, and ethynylcyclohexane have been carried out at temperatures in the range 861–1218 K using the technique of very low‐pressure pyrolysis (VLPP). Multiple reaction pathways and secondary decomposition of primary products results in a complex array of reaction products. VLPP rate data (fall‐off regime) were obtained for the overall decompositions and interpreted via the application of RRKM theory. The data for methylcyclopentane and methylcyclohexane were interpreted in terms of ring‐opening bond fission pathways and bond fission to methyl and cycloalkyl radicals. By selecting Arrhenius parameters consistent with the analogous pathways in open‐chain alkanes, a good fit to the overall decomposition is obtained. The data for ethynylcyclopentane and ethynylcyclohexane were interpreted in terms of ring‐opening bond fission and alkyne to allene isomerization. The A factors for ring opening were based on known values for C‐C fission in open‐chain alkynes and the Arrhenius parameters for isomerization were chosen to be consistent with previously reported alkyne to allene isomerizations. The VLPP data are consistent with the following high‐pressure rate expressions (at < T > = 1100 K) for the dominant primary reaction channel of ring opening adjacent to the substitutent group: where θ = 2.303RT kJ mol−. Comparison of the activation energies for the ethynyl‐cycloalkanes with those for the methyl‐cycloalkanes shows that the effect of the ethynyl substituent is consistent with the propargyl resonance energy. This evidence supports the assumption of a biradical mechanism for ring opening in these cycloalkanes.

Rate constants and product distributions as functions of temperature for the reaction of OH −(H 2O) 0,1,2 with CH 3CN

A selected ion flow tube was used to measure the rate constants and product distributions for the reactions of OH − (H 2O) n with CH 3CN over the temperature range 240–363 K for the case n = 1 and at 298 K for n = 0 and 2. Proton transfer was the only primary reaction channel observed; this process was found to be fast (efficiency ≅ 70%) for n = 0 and 1 but much slower (efficiency ≅ 4%) for n = 2. Interpreting OH − + CH 3CN in the context of the general reaction OH − + CH 3X, two features are important. First, CN has an abnormally large electron affinity. This gives CN − a large methyl cation affinity and nucleophilic displacement a large barrier: it is not observed, even though exothermic. Second, CH 2CN has a large electron affinity and CH 2CN − is delocalized. Thus (1) CH 3CN shows a low heat of deprotonation, making proton transfer exothermic for OH − + CH 3CN, but (2) less than 100% efficient since the product ion is delocalized, and (3) endothermic for OH − (H 2O) 3 + CH 3CN because CH 2CN − has a low hydration energy. Solvent switching with CH 3CN and the thermal dissociation of the solvated product ions were observed as secondary reactions in the OH − (H 2O) + CH 3CN system. This study suggests that thermal dissociation can complicate the interpretation of product distributions in flow-tube and comparable experiments.

ChemInform Abstract: IR Laser Chemistry and C‐F Chromophore Absorption of 1,2‐Dichloro‐1,1,2‐trifluoroethane.

The photochemical-reaction yields after IR multiphoton excitation of CHFCl-CF2Cl are reported and evaluated in terms of the steady-state rate coefficient for reactant decay The dominant primary reaction channels are α,β HCl and HF elimination, although minor pathways seem to include Cl2 elimination and other channels, which are discussed. The major uncertainty in the comparison with theoretical estimates resides in the fraction of CF chromophore band strength which contributes to excitation. The total band strength for the range from 940 cm−1 to 1310 cm−1 is reported to be G = ∫σ(ṽ) (dṽ/ṽ) = 8.2 pm2.

IR Laser Chemistry and CF Chromophore Absorption of 1,2‐Dichloro‐1,1,2‐trifluoroethane

AbstractThe photochemical‐reaction yields after IR multiphoton excitation of CHFCl‐CF2Cl are reported and evaluated in terms of the steady‐state rate coefficient for reactant decay The dominant primary reaction channels are α,β HCl and HF elimination, although minor pathways seem to include Cl2 elimination and other channels, which are discussed. The major uncertainty in the comparison with theoretical estimates resides in the fraction of CF chromophore band strength which contributes to excitation. The total band strength for the range from 940 cm−1 to 1310 cm−1 is reported to be G = ∫σ(ṽ) (dṽ/ṽ) = 8.2 pm2.

Gas-phase photolysis of spiropentane at 147.0 nm

The gas-phase photolysis of spiropentane has been investigated using xenon (147.0 nm) resonance radiation. Major products observed in order of decreasing importance are ethylene, aliène, methylacetylene, 1,2-butadiene, acetylene, propylene, and vinylacetylene. Nitric oxide was used as a radical scavenger while hydrogen sulfide and hydrogen iodide were employed as radical interceptors in the determination of the relative importance of radical and molecular processes. CH3/CH2 and CH3C=C• radicals were identified and quantified. Seven primary reaction channels were postulated of which those involving the "elimination" of ethylene were the most predominant accounting for 71% of the photodecomposition.

Photodissociation of dibromodifluoromethane at 248 nm by the molecular beam method

The photochemistry of CF/sub 2/Br/sub 2/ at 248 nm has been studied by the crossed laser-molecular beam technique. The only primary reaction channel observed is atomic bromine elimination: CF/sub 2/Br/sub 2/ ..-->.. CF/sub 2/Br + Br. Laboratory angular and time-of-flight distributions of the CF/sub 2/Br and Br primary products were measured and used to derive the center-of-mass (CM) product recoil energy and angular distributions for this reaction. The average CM recoil energy of the products is 21.3 kcal/mol. The shape of the CM angular distribution indicates that the transition dipole moment is polarized parallel to the Br-Br direction in CF/sub 2/Br/sub 2/. The molecular bromine elimination reaction, CF/sub 2/Br/sub 2/ ..-->.. CF/sub 2/ + Br/sub 2/, does not occur to a measurable extent at 248 nm. However, CF/sub 2/ radicals are produced in abundance under collision-free conditions, due to the efficient secondary photodissociation of some of the CF/sub 2/Br primary product.

Kinetics and mechanism of the methylidyne + molecular nitrogen reaction. Temperature- and pressure-dependence studies and transition-state-theory analysis

The reaction CH + N/sub 2/ (hydrocarbon radical + nitrogen) ..-->.. products was studied at 297 K at total pressures between 25 and 787 torr. The second-order reaction rate constant was found to be pressure dependent, varying by a factor of 9.6 in this range. This reaction was also studied in the range 297 to 675 K at 100-torr total pressure. The rate constant decreases with increasing temperature and cannot be adequately described by a linear fit in this range. Transition-state (RRKM) theory calculations for the reaction proceeding through a long-lived intermediate, HCN/sub 2/ (diazomethane), sucessfully describe the data. Stabiliztion of the adduct is the primary reaction channel at lower temperatures while metathesis dominates above 1000 K. These calculations provide a consistent description of these and previous data from flame studies. 10 figures, 4 tables.

The production of O(3P) and ground state OH in the reaction of hydrogen atoms with ozone

The production of significant concentrations of O(3P) in the gas phase reaction of hydrogen atoms with ozone in a fast flow discharge system at 1.1±0.1 Torr total pressure in Ar and at room temperature has been reported earlier. These yields were observed to be independent of the concentration of known deactivators of OH† (v = 9) such as O2 and CO2. We report here the results of detailed studies of the yields of O(3P) and ground state OH(X 2πi)v = 0 (OH) using resonance fluorescence under a wide variety of reaction conditions. It is shown that the highest yields of O(3P), 27±2% of the calculated loss of O3 are observed when H is present in excess and the flow tube is coated with a halocarbon wax. The yields are substantially lower when O3 is present in excess and increases as [O3]0 increases. In addition, in an excess of either reagent, the O(3P) yields are lower when the walls of the flow tube are coated with boric acid, which is known to deactivate the vibrationally excited OH† produced in the initial reaction of H with O3. Addition of NO decreased the yield of O(3P), and increased the yield of OH. These results suggest that secondary reactions of OH†, likely with H and O3, are responsible for the production of O(3P), and that a second primary reaction channel, H+O3→HO2+O(3P) [Eq. (lb)] accounts for ?2% of the net reaction.

Vacuum-ultraviolet (147.0 nm and 123.6 nm) photolysis of 1,1-dimethylcyclopropane

The gas-phase photolysis of 1,1-dimethylcyclopropane has been investigated using xenon (147.0 nm) and krypton (123.6 nm) resonance radiation. Major products observed in order of decreasing importance were isobutene, ethylene, hydrogen, 1,3-butadiene 2-methyl-1,3-butadiene, propylene, allene, methylacetylene, and acetylene. Radical scavengers, NO and O2, and radical interceptors, H2S/D2S and HI, were used to determine the relative importance of radical and molecular processes. CH3, C2H3, C3H5, and C4H7 radical species were identified and quantified. Ten primary reaction channels were postulated, of which the elimination of methylene was the most predominant, accounting for 34% of the photo-decomposition at 147.0 nm and 39% at 123.6 nm. Although ionization was established at 123.6 nm (η = 0.10) the nature of a charge transfer or other ion-molecule reaction channel leading to the formation of 2-methyl-1-butene and 2-methyl-2-butene could not be determined.