Rajakumar Balla

RR-GC-FID technique was used to investigate the rate coefficient (k) for the reaction of vinyl butyrate (VB) with Cl atoms in the temperature range of 268 and 363 K at 760 Torr of N2. The k at 298 K was measured to be k298KVB+Cl=2.57±0.68×10-10 cm3 molecule−1 s−1. To comprehend the reaction pathway, and kinetic parameters associated with the title reaction were assessed computationally using CVT/SCT/ISPE method at CCSD(T)//MP2/6-311++G(d,p) level of theory. Product analysis was performed using GC–MS and GC-IR. Cumulative Atmospheric Lifetime (CAL), Radiative Forcing (RF), Global Warming Potential (GWP) and Photochemical Ozone Creation Potential (POCP) were estimated.

The relative rate method was employed to investigate the kinetics of the Cl-initiated reactions of 1-chlorobutane (1-CB) and 2-chlorobutane (2-CB) over 263–363 K, and the measured rate coefficients at room temperature are (1.04 ± 0.24) × 10−10 and (5.84 ± 0.27) × 10−11 cm3 molecule−1 s−1, respectively. The Arrhenius equations for the title reactions were derived to be k1-CB + Cl (T = 263–363 K) = (2.77 ± 0.72) × 10−11 exp [(422 ± 79)/T] and k2-CB + Cl (T = 263–363 K) = (1.40 ± 0.32) × 10−11 exp [(415 ± 70)/T] cm3 molecule−1 s−1, respectively. The products were analysed qualitatively using gas chromatography-mass spectrometry (GC-MS), and the reaction mechanism was proposed for the reactions. The rate coefficients for the title reactions were calculated computationally over the temperature range of 200–400 K using canonical variational transition state theory with appropriate tunnelling corrections at CCSD(T)/6–311++G(2d,2p)//BHandHLYP/6–311++G(2d,2p) level of theory to complement our experimentally measured kinetic parameters. The experimental and theoretical data obtained were used to evaluate the impact of the studied molecules in the troposphere.

The kinetics of the reaction between pinonaldehyde (C 10H16O2) and Cl atom were studied using high level ab initio G3(MP2) and DFT based MPWB1K/6-31 + G(d) and MPW1K/6-31 + G(d) levels of theories coupled with Conventional Transition State Theory in the temperature range between 200 and 400 K. The negative temperature dependent rate expression for the title reaction obtained with Wigner’s and Eckart’s symmetrical tunneling corrections are k(T) =(5.1 ± 0.56) × 10 −19T2.35exp[(2098 ± 2)/T] cm 3 molecule −1s−1, and k(T) =(0.92 ± 0.18) × 10 −19T2.60exp[(2204 ± 4)/T] cm 3 molecule −1 s −1, respectively, at G3(MP2)//MPWB1K method. The H abstraction reaction from the –CHO group was found to be the most dominant reaction channel among all the possible reaction pathways and its corresponding rate coefficient at 300 K is k(Eckart’s unsymmetrical) = 3.86 ×10−10 cm 3 molecule −1 s −1. Whereas the channel with immediate lower activation energy is the H-abstraction from –CH- group (Tertiary H-abstraction site, C g). The rate coefficient for this channel is k Cg(Eckart’s unsymmetrical) = 1.83 ×10−15 cm 3 molecule −1 s −1 which is smaller than the dominant channel by five orders of magnitude. The atmospherically relevant parameters such as lifetimes were computed in this investigation of its reaction with Cl atom. [Figure not available: see fulltext.]

The rate coefficients for the reaction of CH3CF = CF2 with OH radicals were calculated using CCSD(T)/cc-pVTZ//M06-2X/6-31G(d,p) level of theory over the temperature range of 200–400 K. Canonical Variation Transition state theory (CVT) in combination with Small Curvature Tunneling (SCT) was employed to calculate the rate coefficients for the title reaction. The temperature dependent rate coefficient for the reaction of OH radicals with CH3CF = CF2 was calculated to be (5.77 ± 2.55) × 10−25 T3.76 exp [(2355 ± 37)/T] cm3 molecule−1 s−1. Thermodynamic parameters, branching ratios and atmospheric implications of the title reaction were also computed and discussed in the article.