scholarly journals Direct observation and kinetics of a hydroperoxyalkyl radical (QOOH)

Science ◽  
2015 ◽  
Vol 347 (6222) ◽  
pp. 643-646 ◽  
Author(s):  
John D. Savee ◽  
Ewa Papajak ◽  
Brandon Rotavera ◽  
Haifeng Huang ◽  
Arkke J. Eskola ◽  
...  
Keyword(s):  
Organic Compounds ◽  
Direct Observation ◽  
Organic Aerosol ◽  
Organic Radicals ◽  
Radical Chain ◽  
Radical Intermediates ◽  
Oxidation Of Organic Compounds ◽  
Resonance Stabilization ◽  
Kinetics Of ◽  
Insight Into

Oxidation of organic compounds in combustion and in Earth’s troposphere is mediated by reactive species formed by the addition of molecular oxygen (O2) to organic radicals. Among the most crucial and elusive of these intermediates are hydroperoxyalkyl radicals, often denoted “QOOH.” These species and their reactions with O2 are responsible for the radical chain branching that sustains autoignition and are implicated in tropospheric autoxidation that can form low-volatility, highly oxygenated organic aerosol precursors. We report direct observation and kinetics measurements of a QOOH intermediate in the oxidation of 1,3-cycloheptadiene, a molecule that offers insight into both resonance-stabilized and nonstabilized radical intermediates. The results establish that resonance stabilization dramatically changes QOOH reactivity and, hence, that oxidation of unsaturated organics can produce exceptionally long-lived QOOH intermediates.

scholarly journals The kinetics of the oxidation of mixtures of ethylene and acetaldehyde

1934 ◽  
Vol 146 (856) ◽  
pp. 72-82 ◽  
Keyword(s):  
Organic Compounds ◽  
Practical Importance ◽  
Initial Step ◽  
Chain Reactions ◽  
Oxidation Of Organic Compounds ◽  
Real Relation ◽  
Gaseous Hydrocarbons ◽  
A Chain ◽  
Hydroxyl Compounds ◽  
Kinetics Of

The oxidation of gaseous hydrocarbons has long attracted considerable interest on account pf its theoretical and practical importance. Early work was concerned entirely with the identification of the products of oxidation, and the postulation of plausible intermediate steps in their formation. As a result of such work Bone and his collaborators suggested the so-called "hydroxylation theory", which involved the orderly formation of hydroxyl compounds during oxidation, and their subsequent decomposition of further oxidation. This theory gives an excellent explanation of the intermediate and final products formed in the oxidation of most simple hydrocarbons. As far as the mechanism of the actual oxidation process is concerned, little progress was made until the development of the idea of thermal chain reactions. It is now generally conceded that the oxidation of most gaseous organic compounds proceeds by a chain mechanism. The main problem at the present time is to obtain some definite information regarding the carriers of the chains. One of the most useful attempts in this direction is the peroxide theory of Egerton, in which it is assumed that the initial step in the oxidation of organic compounds is the formation of an energy-rich complex with oxygen, which is called a "peroxide". Whether such a complex bears any real relation to actual stable alkyl peroxides is quite unknown.

scholarly journals Explicit modelling of SOA formation from α-pinene photooxidation: sensitivity to vapour pressure estimation

2011 ◽  
Vol 11 (3) ◽  
pp. 10121-10158 ◽  
Author(s):  
R. Valorso ◽  
B. Aumont ◽  
M. Camredon ◽  
T. Raventos-Duran ◽  
C. Mouchel-Vallon ◽  
...  
Keyword(s):  
Organic Compounds ◽  
Vapour Pressure ◽  
Estimation Method ◽  
Organic Aerosol ◽  
Reaction Scheme ◽  
Oxidation Products ◽  
Organic Species ◽  
Structure Activity ◽  
Volatile Organic ◽  
Kinetics Of

Abstract. The sensitivity of the formation of secondary organic aerosol (SOA) to the estimated vapour pressures of the condensable oxidation products is explored. A highly detailed reaction scheme was generated for α-pinene photooxidation using the Generator for Explicit Chemistry and Kinetics of Organics in the Atmosphere (GECKO-A). Vapour pressures (Pvap) were estimated with three commonly used structure activity relationships. The values of Pvap were compared for the set of secondary species generated by GECKO-A to describe α-pinene oxidation. Discrepancies in the predicted vapour pressures were found to increase with the number of functional groups borne by the species. For semi-volatile organic compounds (i.e. organic species of interest for SOA formation), differences in the predicted Pvap range between a factor of 5 to 200 in average. The simulated SOA concentrations were compared to SOA observations in the Caltech chamber during three experiments performed under a range of NOx conditions. While the model captures the qualitative features of SOA formation for the chamber experiments, SOA concentrations are systematically overestimated. For the conditions simulated, the modelled SOA speciation appears to be rather insensitive to the Pvap estimation method.

Determination of the chain termination rate constants of the radical chain oxidation of organic compounds on antioxidant molecules by the QSPR method

2020 ◽  
Vol 69 (9) ◽  
pp. 1679-1691
Author(s):  
Yu. Z. Martynova ◽  
V. R. Khairullina ◽  
R. N. Nasretdinova ◽  
G. G. Garifullina ◽  
D. S. Mitsukova ◽  
...  
Keyword(s):  
Organic Compounds ◽  
Rate Constants ◽  
Chain Termination ◽  
Radical Chain ◽  
Chain Oxidation ◽  
Termination Rate ◽  
Radical Chain Oxidation ◽  
Oxidation Of Organic Compounds
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