![]() ![]() Molecular characterization and microscopy analysis of biomass burning organic aerosols (BBOA) including tar balls showed uniform distribution of nonvolatile NOC 11, with only 14 ± 3% of the N-bearing compounds occur as ammonium sulfate 12. Primary emission sources of NOC particles were estimated to be 27.4 Tg yr −1 from biogenic, soil, ocean, and anthropogenic (that includes biomass burning) sources 9. Nitrogen-containing organic carbon (NOC) in atmospheric particles are increasing in importance as a class of BrC 6, 7, 8, which originates from primary and secondary sources 9, 10. The majority of BrC originates from biomass burning events and their cloud condensation nuclei activity and hygroscopicity parameter, κ, ranges from 0.1 to 0.4, which slightly increases upon particle photochemical or oxidative aging 5. Atmospheric BrC refers to the class of organic compounds that efficiently absorb solar and terrestrial radiation. Quantifying the contribution of atmospheric brown carbon (BrC) to climate forcing and aerosol-cloud interactions remains a large source of uncertainty in climate models due to their chemical complexity and variable sources 1, 2, 3, 4. These results highlight the important role of iron redox chemistry in BrC formation under atmospherically relevant conditions. Heterogeneous reactions of aminophenol were also conducted using Arizona Test Dust (AZTD) under simulated aging conditions, and showed clear changes to optical properties, morphology, mixing state, and chemical composition. ![]() Soluble products analyzed using chromatography and mass spectrometry revealed the formation of ring coupling products of o- and p-aminophenols and their primary oxidation products. Hygroscopicity growth factors (κ) of these insoluble products under sub- and super-saturated conditions ranged from 0.4–0.6, higher than that of levoglucosan, a prominent proxy for biomass burning organic aerosol (BBOA). Mass yield experiments of insoluble soot-like dark brown to black particles were as high as 40%. Homogeneous aqueous phase reactions were conducted using soluble Fe(III), where particle growth/agglomeration were monitored using dynamic light scattering. Here we show that iron can catalyze dark oxidative oligomerization of o- and p-aminophenols under simulated aerosol and cloud conditions (pH 1–7, and ionic strength 0.01–1 M). Redox active NOC like aminophenols received little attention in their ability to form BrC. A carbanion is a nucleophile (from “nucleus” and phile), an electron-rich species that has a pair of electrons available to share with another atom.Nitrogen-containing organic carbon (NOC) in atmospheric particles is an important class of brown carbon (BrC). The methyl anion (CH 3 −) has a structure that is similar to NH 3 with its lone pair of electrons, but it has a much stronger tendency to share its lone pair with another atom or molecule. Because it has a strong tendency to share its lone pair with another atom or molecule, a carbanion is a nucleophile.Īdding an electron to a radical produces a carbanion, which contains a negatively charged carbon with eight valence electrons (part (c) in Figure 24.3.1). (c) The simplest organic carbanion is CH 3 −, which has a trigonal pyramidal structure with an sp 3 hybridized carbon that has a lone pair of electrons. It is also sp 2 hybridized, but there is a single electron in the unhybridized p orbital. (b) The methyl radical (♼H 3) is a radical that, like the carbocation, is trigonal planar and an electrophile. Its structure is trigonal planar, with an sp 2 hybridized carbon and a vacant p orbital. (a) The simplest carbocation is the methyl cation (CH 3 ), which has six valence electrons and is an electrophile. \): Transient Intermediates in Organic Reactions.
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