Atmosfere karışan bazı organik bileşiklerin yapısal özelliklerinin ve tepkimelerinin moleküler orbital yöntemleriyle incelenmesi

Abstract

Bu çal,-mada, hidroksil radikali (.OH), hidroksil radikali-su kompleksi (HO.-H2O), nitrat radikali (NO3.) ve nitrat radikali-su kompleksi (NO3.-H2O) ile metan, etanve propan,n gaz faz,ndaki hidrojen ayr,lma tepkimeleri B3LYP/6-311++G(d,p) veB3LYP/6-311++G(2df,2pd) düzeyinde DFT (YoAunluk Fonksiyonel Teori) yöntemikullan,larak incelendi. Her bir tepkimenin tepkenleri, tepken kompleksleri,geçi- halleri,ürün kompleksleri ve ürünlerine ait geometrik yap,lar optimize edildi. Geçi- halleri,ayn, düzeyde yap,lan frekans hesaplamalar,nda sadece bir tane sanal frekansbulunmas,yla doAruland,.HO.-H2O .kompleksi tepkimelerinin OH radikali tepkimeleriylekar-,la-t,r,ld,A,nda hem kinetik hem de termodinamik olarak tercih edilmediAisonucuna var,ld,. Bununla birlikte NO3.-H2O tepkimelerinin NO3. radikal tepkimelerinegöre termodinamik olarak tercih edildiAi fakat kinetik olarak tercih edildiAi görüldü.Anahtar kelimeler: Atmosferik kimya, Hidrojen ayr lma tepkimeleri, Radikal-sukompleksleri, Yo unluk fonksiyonel teori, Geçi hali

In this study, hydrogen abstraction reactions of methane, ethane and propanewith hydroxyl radical (.OH), hydroxyl radical-water complex (HO.-H2O), nitrate radical(NO3.) and nitrate radical-water complex (NO3.-H2O) were investigated using DFT(Density Functional Theory) method at the B3LYP/6-311++G(d,p) and B3LYP/6-311++G(2df,2pd) levels in the gas phase. Geometric structures for the reactants,reactant complexes, transition states, product complexes and products of each reactionwere optimized. The transition states were confirmed by observing a single imaginaryfrequency in the same level frequency calculations . Unrestricted formalisms were usedfor the radicals.We concluded that the reactions of HO.-H2O complex are unfavorable bothkinetically and thermodynamically as compared to reactions of .OH radical. Howeverthe reactions of NO3.-H2O complex are thermodynamically more favorable butkinetically less favorable than reactions of NO3. radical.Keywords: Atmospheric chemistry, Hydrogen abstraction reactions, Radical-watercomplexes, Density functional theory, Transition state