Quantum Chemical Investigation of OH-Initiated Oxidation Kinetics of Ethyl 2-Chloroacetoacetate in the Atmosphere
Narendra Pramanik
Department of Chemistry, Himalayan University, Jullang-791111, Arunachal Pradesh, India.
Nabam Tayum
Department of Chemistry, North-Eastern Regional Institute of Science and Technology, Nirjuli-791109, Arunachal Pradesh, India.
Nand Kishor Gour
Department of Chemical Sciences, Tezpur University, Tezpur, Napaam, Assam – 784 028, India.
Arumugam Murugan
Department of Chemistry, North-Eastern Regional Institute of Science and Technology, Nirjuli-791109, Arunachal Pradesh, India.
Devaprasad Dev *
Department of Chemistry, Himalayan University, Jullang-791111, Arunachal Pradesh, India.
Bhupesh Kumar Mishra *
Department of Chemistry, Dera Natung Government College, Itanagar- 791113, Arunachal Pradesh, India.
*Author to whom correspondence should be addressed.
Abstract
Anthropogenic sources release ethyl 2-chloroacetoacetate (CH₃C(O)CHClC(O)OCH2CH₃, E2CAA), a family of organic volatile chemicals, into the environment from the paper industry. Concerns over its effects on the environment are raised by its widespread use in industrial activities. Using the M06-2X functional, we carried out a thorough theoretical analysis of the atmospheric oxidation processes of E2CAA that are started by OH radicals. At room temperature, the most thermodynamically stable conformer of E2CAA was found. Four primary hydrogen abstraction pathways were characterized, each proceeding through the formation of reaction complexes, indicating that the reactions follow an indirect hydrogen abstraction mechanism. Canonical Transition State Theory (CTST) was used to compute and analyze the reaction coefficients and product branching ratios for H-abstraction channels in the temperature range of 250–450 K. Based on these kinetic results, the atmospheric lifetime of E2CAA was estimated to be approximately 4.41 hours.
Keywords: Ester, chloroacetoacetate, DFT, IRC calculation, rate constant