Peroxyacyl nitrates: Difference between revisions

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In [[organic chemistry]], ”’peroxyacyl nitrates”’ (also known as ”’Acyl peroxy nitrates”’, ”’APN”’ or ”’PANs”’) are powerful respiratory and eye irritants present in [[photochemical smog]]. They are [[nitrates]] produced in the [[thermal equilibrium]] between organic [[peroxy]] [[radical (chemistry)|radical]]s by the [[gas]]-phase [[oxidation]] of a variety of [[volatile organic compound]]s (VOCs), or by [[aldehyde]]s and other oxygenated VOCs oxidizing in the presence of {{chem2|NO2}}.<ref>{{cite journal |doi=10.1016/S0269-7491(02)00273-7|title=Effects of airborne volatile organic compounds on plants |year=2003 |last1=Cape |first1=J.N. |journal=Environmental Pollution |volume=122 |issue=1 |pages=145–157 |pmid=12535603 }}</ref><ref>{{cite journal |doi=10.1021/acsearthspacechem.1c00143|title=The Impacts of Peroxyacetyl Nitrate in the Atmosphere of Megacities and Large Urban Areas: A Historical Perspective |year=2021 |last1=Gaffney |first1=Jeffrey S. |last2=Marley |first2=Nancy A. |journal=ACS Earth and Space Chemistry |volume=5 |issue=8 |pages=1829–1841 |bibcode=2021ESC…..5.1829G |s2cid=238708473 }}</ref><ref>{{cite journal |doi=10.1098/rstb.2013.0115|title=The cycling of organic nitrogen through the atmosphere |year=2013 |last1=Jickells |first1=T. |last2=Baker |first2=A. R. |last3=Cape |first3=J. N. |last4=Cornell |first4=S. E. |last5=Nemitz |first5=E. |journal=Philosophical Transactions of the Royal Society B: Biological Sciences |volume=368 |issue=1621 |pmid=23713115 |pmc=3682737 }}</ref>

In [[organic chemistry]], ”’peroxyacyl nitrates”’ (also known as ”’Acyl peroxy nitrates”’, ”’APN”’ or ”’PANs”’) are powerful respiratory and eye irritants present in [[photochemical smog]]. They are [[nitrates]] produced in the [[thermal equilibrium]] between organic [[peroxy]] [[ (chemistry)|]] by the [[gas]]-phase [[oxidation]] of a variety of [[ organic compound]] (VOCs) by [[]] and other oxygenated VOCs oxidizing in the presence of .<ref>{{ journal |=.|title=Effects of airborne volatile organic compounds on plants |= |journal=Environmental Pollution |volume=122 |issue=1 |pages= |= }}</ref><ref>{{ journal |=..|title=The Impacts of Peroxyacetyl Nitrate in the Atmosphere of Megacities and Large Urban Areas: A Historical Perspective |journal=ACS Earth and Space Chemistry |volume=5 |issue=8 |pages= |=2021ESC…..5.1829G 238708473}}</ref><ref>{{ journal |=Jickells |=T. |last2=Baker |first2=A.R. |last3=Cape |first3=J.N. |last4=Cornell |first4=S.E. |last5=Nemitz |first5=E. |journal=Philosophical Transactions of the Royal Society B: Biological Sciences |volume=368 |issue=1621 |= 3682737 }}</ref>

They are good markers for the source of VOCs as either biogenic or anthropogenic, which is useful in the study of global and local effects of pollutants.<ref name=LaFranchi2009>{{cite journal |last1=LaFranchi |first1=B. W. |last2=Wolfe |first2=G. M. |year=2009 |title=Closing the peroxy acetyl nitrate budget: observations of acyl peroxy nitrates (PAN, PPN, and MPAN) during BEARPEX 200 |journal=Atmos. Chem. Phys. |publisher=Copernicus Publications |volume=9 |issue= 19|pages=7623–7641 |url=https://www.atmos-chem-phys.net/9/7623/2009/acp-9-7623-2009.pdf |doi=10.5194/acp-9-7623-2009|bibcode=2009ACP.….9.7623L |doi-access=free}}</ref><ref>{{cite web |url=https://atmos.uw.edu/~thornton/PANs.html |title=PANs |first=Joel |last=Thornton |publisher=Department of Atmospheric Sciences, University of Washington |access-date=14 November 2010}}</ref>

They are good markers for the source of VOCs as either biogenic or anthropogenic, which is useful in the study of global and local effects of pollutants.<ref name=>{{ journal |=LaFranchi |=B.W. |last2=Wolfe |first2=G.M. |=2009 |title=Closing the peroxy acetyl nitrate budget: observations of acyl peroxy nitrates (PAN, PPN, and MPAN) during BEARPEX 200 |journal=Atmos. Chem. Phys. |volume=9 |issue= |pages= |=:..9. doi10.5194/acp-9-7623-2009.}}</ref><ref>{{ |= |first=Joel |= |=Department of Atmospheric Sciences, University of Washington}}</ref>

==Formation==

==Formation==

PANs are secondary pollutants, which means they are not directly emitted as exhaust from [[fossil fuel power plant|power plants]] or [[internal combustion engines]], but they are formed from other pollutants by chemical reactions in the atmosphere. [[Free radical]] reactions catalyzed by [[ultraviolet light]] from the sun oxidize unburned non-methane<ref name=”Fischer2014“/>{{rp|p=2679}} [[hydrocarbons]] to [[aldehydes]], [[ketones]], and [[dicarbonyl]]s, whose secondary reactions create peroxyacyl radicals. The most common peroxyacyl radical is peroxyacetyl, which can be formed from the free radical oxidation of [[acetaldehyde]], various ketones, or the [[photodissociation|photolysis]] of dicarbonyl compounds such as [[methylglyoxal]] or [[diacetyl]].

PANs are secondary pollutants, which means they are not directly emitted as exhaust from [[ fuel power plant|power plants]] or [[internal combustion engines]], but they are formed from other pollutants by chemical reactions in the atmosphere. [[Free radical]] reactions catalyzed by [[ultraviolet light]] from the sun oxidize unburned non-methane<ref name=””>{{|=2679}} [[hydrocarbons]] to [[aldehydes]], [[ketones]], and [[]], whose secondary reactions create peroxyacyl radicals. The most common peroxyacyl radical is peroxyacetyl, which can be formed from the free radical oxidation of [[acetaldehyde]], various ketones, or the [[|photolysis]] of dicarbonyl compounds such as [[methylglyoxal]] or [[diacetyl]].

These react reversibly with [[nitrogen dioxide]] ({{chem2|NO2}}) to form PANs:<ref name=”Fischer2014″>{{cite journal |last1=Fischer |first1=E. V. |last2=Jacob |first2=D. J. |last3=Yantosca |first3=R. M. |last4=Sulprizio |first4=M. P. |last5=Millet |first5=D. B. |last6=Mao |first6=J. |last7=Paulot |first7=F. |last8=Singh |first8=H. B. |last9=Roiger |first9=A. |last10=Ries |first10=L. |last11=Talbot |first11=R.W. |last12=Dzepina |first12=K. |last13=Pandey Deolal |first13=S. |title=Atmospheric peroxyacetyl nitrate (PAN): a global budget and source attribution |journal=Atmospheric Chemistry and Physics |date=14 March 2014 |volume=14 |issue=5 |pages=2679–2698 |doi=10.5194/acp-14-2679-2014 |doi-access=free|pmc=7983850 }}</ref>{{rp|p=2680}}

Night-time reaction of [[aldehydes]] with [[nitrogen trioxide]] is another possible source.<ref name=”Fischer2014“/>{{rp|p=2680}}

with [[nitrogen ]] <ref name=””/>

Since they dissociate quite slowly in the atmosphere into [[radical (chemistry)|radical]]s and {{chem2|NO2}}, PANs are able to transport these unstable compounds far away from the urban and industrial origin. This is important for [[tropospheric ozone]] production as PANs transport [[NOx|NO_”x”]] to regions where it can more efficiently produce [[ozone]].

Night-time reaction of [[aldehydes]] with [[nitrogen trioxide]] is another possible source.<ref name=”:1″ />

The stability of PANs in the atmosphere is dependent on temperature. Lower temperatures in the troposphere increase the stability and therefore lifetime of PANs.<ref>{{Cite journal |last=Jenkin |first=Michael E. |last2=Clemitshaw |first2=Kevin C. |date=2000 |title=Ozone and other secondary photochemical pollutants: chemical processes governing their formation in the planetary boundary layer |journal=Atmospheric Environment |volume=34 |issue=16 |pages=2499-2527 |via=doi.org/10.1016/S1352-2310(99)00478-1}}</ref> Since they dissociate quite slowly in the atmosphere into [[Radical (chemistry)|radicals]] and NO₂, PANs are able to transport these unstable compounds far away from their urban and industrial origins. There is a decrease in photochemical ozone formation as the PANs are a [[NOx|NO_”x”]] reservoir decreasing the amount of [[NOx|NO_”x”]] that can be photolyzed.<ref>{{Cite journal |last=Gil |first=Junsu |last2=Lee |first2=Meehye |last3=Han |first3=Jihyun |last4=Kim |first4=Joo-Ae |last5=Kim |first5=Saewung |last6=Guenther |first6=Alex |last7=Kim |first7=Hyunseok |last8=Kim |first8=Soyoung |last9=Lee |first9=Sanguk |last10=Kim |first10=Danbi |date=2018 |title=Peroxyacetyl Nitrate and Ozone Enhancement at Taehwa Research Forest under the Influence of Seoul Metropolitan Area |journal=Aerosol Air Qual. Res. |volume=18 |pages=2262-2273 |via=doi.org/10.4209/aaqr.2017.11.0451}}</ref>This is important for [[tropospheric ozone]] production as PANs transport [[NOx|NO_”x”]] to regions where it can more efficiently produce [[ozone]].

==Types==

==Types==

[[Peroxyacetyl nitrate]] is the most prevalent peroxyacyl nitrate (75–90% of total atmospheric emissions),<ref name=”Fischer2014“/>{{rp|p=2681}} followed by peroxypropionyl nitrate (PPN).<ref name=”Kleindienst1990“>{{cite journal |last1=Kleindienst |first1=Tadeusz E. |last2=Shepson |first2=Paul B. |last3=Smith |first3=David F. |last4=Hudgens |first4=Edward E. |last5=Nero |first5=Chris M. |last6=Cupitt |first6=Larry T. |last7=Bufalini |first7=Joseph J. |last8=Claxton |first8=Larry D. |last9=Nestman |first9=F. R. |title=Comparison of mutagenic activities of several peroxyacyl nitrates |journal=Environmental and Molecular Mutagenesis |date=January 1990 |volume=16 |issue=2 |pages=70–80 |doi=10.1002/em.2850160204}}</ref> Peroxybenzoyl nitrate (PBzN)<ref name=”Kleindienst1990“/> and [[Methacrylic acid|methacryloyl]] peroxynitrate (MPAN)<ref name=LaFranchi2009/> have also been observed. The composition of PANs in a particular region depends heavily on which hydrocarbons are present in the atmosphere, with the exception of peroxyacetyl nitrate, which is able to be produced from a range of precursors.<ref name=LaFranchi2009/>{{rp|p=7624}}

[[Peroxyacetyl nitrate]] is the most prevalent peroxyacyl nitrate (75–90% of total atmospheric emissions),<ref name=””/>{{|=}}followed by peroxypropionyl nitrate (PPN)<ref name=””>{{ journal |=Kleindienst |=Tadeusz E. |last2=Shepson |first2=Paul B. |last3=Smith |first3=David F. |last4=Hudgens |first4=Edward E. |last5=Nero |first5=Chris M. |last6=Cupitt |first6=Larry T. |last7=Bufalini |first7=Joseph J. |last8=Claxton |first8=Larry D. |last9=Nestman |first9=F.R. |title=Comparison of mutagenic activities of several peroxyacyl nitrates |journal=Environmental and Molecular Mutagenesis |volume=16 |issue=2 |pages= |=10.1002/em.2850160204}}</ref> Peroxybenzoyl nitrate (PBzN)<ref name=””/> and [[Methacrylic acid|methacryloyl]] peroxynitrate (MPAN)<ref name=/> have also been observed. The composition of PANs in a particular region depends heavily on which hydrocarbons are present in the atmosphere, with the exception of peroxyacetyl nitrate, which is able to be produced from a range of precursors.<ref name=/>

==Health effects==

==Health effects==

PANs are both toxic and irritating, as they dissolve more readily in water than [[ozone]]. They are [[lachrymator]]s, causing eye irritation at concentrations of only a few parts per billion. At higher concentrations they cause extensive damage to vegetation. PANs are [[mutagen]]ic,<ref name=“Kleindienst1990″/> and are considered potential contributors to the development of skin cancer.{{citation needed|date=December 2024}}

PANs are both toxic and irritating, as they dissolve more readily in water than [[ozone]]. They are [[]], causing eye irritation at concentrations of only a few parts per billion. At higher concentrations they cause extensive damage to vegetation. = .{{ | }}

==References==

==References==