Combustive, Postcombustive, and Tropospheric Butadiyne Oxidation by O2, Following Initial HO Attack. Theoretical Study.

摘要: Butadiyne (diacetylene, HC(4)H) is produced during combustions, and has been quantified in different flames as well a biomass burning emission. Its reaction with the hydroxyl radical, HO((2)Π(3/2)), under combustion conditions, was investigated thorough RRKM study by J. P. Senosiain, S. Klippenstein, A.Miller (Proc. Combust. Inst. 2007, 31, 185−192). The present densityfunctional theory (DFT) focuses on mechanism of further oxidation O(2)(3Σ(g)(−)). DFT(M06-2X)/cc-pVTZ energy hypersurface for system C(4)H(2)/HO•/O(2) studied to define variety pathways, relevant thermochemistry temperatures ranging from 200 2500 K assessed, thus encompassing combustive, postcombustive, tropospheric conditions.Energies are then recomputed at coupled cluster level[CCSD(T)/cc-pVTZ], combined DFT thermochemistry.Finally, role channels assessed RRKM-ME simulations same temperature range P = 1 atm,to comprise situation emission troposphere those pertaining flames. This shows that, when considering HO addition triple bond, dioxygen takes part C(4)H(2) higher efficiency lower temperatures, whereas, T rises, O(2) adducts inclined redissociate: instance, 50% redissociation estimated 1800 K. For < 1100 K, two polycarbonyl products (CHO.CO.CCH CHO.CO.CHCO) fragmentation (HCOOH plus OC(•)−CCH) main species predicted channel (fragmentation entropy-favored values). However, aninitial H abstraction can give but adiynyl radical (HC(4)(•)) starting point subsequent intervention.Then, new pathways opened become accessible bring about fragmentations mainly HC(3)(•) + CO(2) also HC(3)(•)O CO.