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The '''mesomeric effect''' or '''resonance effect''' in [[chemistry]] is a property of [[substituent]]s or [[functional group]]s in a [[chemical compound]]. The effect is used in a qualitative way and describes the electron withdrawing or releasing properties of substituents based on relevant [[resonance structure]]s and is symbolized by the letter '''M'''. The mesomeric effect is negative ('''-M''') when the substituent is an electron-withdrawing group and the effect is positive ('''+M''') when based on resonance the substituent is an electron releasing group.
{{Infobox_Biography |
subject_name = Norman Fitzroy Maclean |
image_name = norman_maclean.jpg |
image_caption = [[United States|American]] [[writer]] |
date_of_birth = [[December 23]], [[1902]] |
place_of_birth = [[Clarinda, Iowa|Clarinda]], [[Iowa]], [[USA]] |
date_of_death = [[August 2]], [[1990]] |
place_of_death = [[Chicago, Illinois|Chicago]], [[Illinois]], [[USA]]
}}
'''Norman Fitzroy Maclean''' ([[December 23]], [[1902]] – [[August 2]], [[1990]]) was born in [[Clarinda, Iowa|Clarinda]], [[Iowa]]. In [[1909]], his family moved to [[Missoula, Montana]] where he grew up along with his younger brother, Paul. Until [[1913]], he and his brother were educated by his father, a Scotch [[Presbyterian]] minister, instead of attending public schools. He later wrote of this experience in ''The Woods, Books, and Truant Officers,'' and briefly in ''A River Runs Through It'' (1976). In his youth, Maclean worked in logging camps and for the [[United States Forest Service]] in what is now the [[Bitterroot National Forest]] of southwest [[Montana]]. The short story ''USFS 1919: The Ranger, the Cook, and a Hole in the Sky'' and the story ''Black Ghost'' in ''Young Men and Fire'' (1992) are semi-fictionalized accounts of these experiences.
*Examples of -M substituents: [[acetyl]] (UPAC ethanoyl) - [[nitrile]] - [[nitro]]
Maclean received his [[BA|Bachelor of Arts]] from [[Dartmouth College]] in [[1924]], and served as an instructor there until [[1926]], a time he recalled in ''This Quarter I'm Taking McKean: A Few Remarks on the Art of Teaching''. He began graduate studies in [[English studies|English]] at the [[University of Chicago]] in [[1928]]. Three years later he was hired as a professor at [[University of Chicago]], where he went on to receive three [[Quantrell Awards for Excellence in Undergraduate Teaching]]. It was during this time that Maclean married Jessie Burns, a red-headed Scotch-Irish woman from [[Helena, Montana|Helena]]. They later had two children, their daughter Jean, born in [[1942]], is now a lawyer. Their son John, born in [[1943]], is now a journalist and author of ''Fire on the Mountain: The True Story of the South Canyon Fire'' (1999).
*Examples of +M substituents: [[alcohol]] - [[amine]]
The net electron flow from or to the substituent is determined also by the [[inductive effect]]. It's important to note that the mesomeric effect as a result of p - orbital overlap (resonance) has absolutely no effect on this inductive effect, as the inductive effect is purely to do with the [[electronegativity]] of the atoms and their structural chemistry (which atoms are connected to which).
In [[1940]], Maclean earned his [[Ph.D|doctorate]] from the University of Chicago where during [[WWII]] he served as Dean of Students and as Director of the Institute on Military Studies, and co-authored ''Manual of Instruction in Military Maps and Aerial Photographs''. Maclean, a scholar of [[William Shakespeare|Shakespeare]] and the [[Romanticism|Romantic poets]], was William Rainey Harper Professor of English at the University of Chicago until he retired in [[1973]]. He then began, as his children had often encouraged him, to write down the stories he liked to tell. His most acclaimed work, ''A River Runs Through It and Other Stories'' was published in 1976, the first [[fiction]] ever published by the [[University of Chicago Press]]. This title had nearly unanimous support by critics to receive the [[Pulitzer Prize]] in Letters in [[1977]], but the story, a semi-fictional account of Maclean's family, was deemed to be to close to real life to be considered fiction. ''[[A River Runs Through It]]'' was adapted into a motion picture directed by [[Robert Redford]] and released by [[Columbia Pictures]] starring [[Brad Pitt]] and [[Tom Skeritt]].
The concepts of mesomeric effect, '''mesomerism''' and '''mesomer''' were introduced by [[Christopher Kelk Ingold|Ingold]] in 1938 as an alternative to the [[Linus Pauling|Pauling's]] synonymous concept of [[resonance effect|resonance]] <ref>''If It's Resonance, What Is Resonating?'' Kerber, Robert C. . J. Chem. Educ. '''2006''' 83 223. [http://www.jce.divched.org/Journal/Issues/2006/Feb/abs223.html Abstract]</ref>. Mesomerism is in this context is often encountered in German and French literature but in English literature the term resonance dominates.
Maclean's books and short stories, ending with ''Young Men and Fire'' (1992) published after his death, tell his and his family's story. ''Young Men and Fire'' was the winner of the [[National Book Critics Circle Award]] in 1992.
== External links==
Norman Maclean, one of the greatest American storytellers, passed away [[August 2]], [[1990]] in [[Chicago, Illinois|Chicago]], at the age of 87.
* IUPAC [[Gold Book]] [http://www.iupac.org/goldbook/M03844.pdf definition]
== See also ==
* [[List of publications in chemistry#Organic chemistry|Important publications in organic chemistry]]
== References ==
<references />
This text (with minor alteration) is taken with permission from [[http://www.thelandos.com/norman_maclean.htm|http://www.thelandos.com/norman_maclean.htm]]
[[Category:Chemical bonding]]
[[de:Mesomerer Effekt]]
[[Category:1902 births|Maclean, Norman]]
[[Category:1990 deaths|Maclean, Norman]]
[[Category:American writers|Maclean, Norman]]
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