{{short description|British chemist (1893–1970)}} {{Use British English|date=July 2017}} {{Use dmy dates|date=July 2017}} {{Infobox scientist | honorific_prefix = Sir | name = Christopher Kelk Ingold | honorific_suffix = {{Post-nominals|country=GBR|BEM|FRS|size=100%}} | image = Christopher Kelk Ingold portrait.jpg | image_size = | caption = Ingold, as photographed in Michigan State University. | birth_date = {{birth date|df=yes|1893|10|28}} | birth_place = London, England | death_date = {{death date and age|df=yes|1970|12|8|1893|10|28}} | death_place = Edgware, London, England | field = Chemistry | work_institutions = Imperial College London<br>University of Leeds<br>University College London | education = Hartley University College (now University of Southampton)<br>Imperial College London | academic_advisors = Jocelyn Field Thorpe | doctoral_students = Ronald Gillespie<br>Ronald Sydney Nyholm<ref> {{cite Australian Dictionary of Biography |first = Stanley E.| last = Livingstone|title = Nyholm, Sir Ronald Sydney (1917–1971)|id2=nyholm-sir-ronald-sydney-11269}}</ref><br> Peter de la Mare | thesis_title = Formation and stability of carbon rings | awards = {{Plainlist|class=nowrap| * Davy Medal (1946) * Royal Medal (1952) * Faraday Lectureship Prize (1961) }} | thesis_year = 1921 | known_for = Organic reaction mechanisms<br>Cahn–Ingold–Prelog priority rules<br>Hughes–Ingold rules<br>Thorpe–Ingold effect | signature = Ingold podp.jpg }}
'''Sir Christopher Kelk Ingold''' {{Post-nominals|country=GBR|BEM|FRS}}<ref name="frs">{{Cite journal | last1 = Shoppee | first1 = C. W. |author-link= Charles Shoppee | doi = 10.1098/rsbm.1972.0012 | title = Christopher Kelk Ingold. 1893-1970 | journal = Biographical Memoirs of Fellows of the Royal Society | volume = 18 | pages = 348–411| year = 1972 | doi-access = free }}</ref> (28 October 1893 – 8 December 1970) was a British chemist based in Leeds and London. His groundbreaking work in the 1920s and 1930s on reaction mechanisms and the electronic structure of organic compounds was responsible for the introduction into mainstream chemistry of concepts such as nucleophile, electrophile, inductive and resonance effects, and such descriptors as S<sub>N</sub>1, S<sub>N</sub>2, E1, and E2 now known as the ''Hughes–Ingold symbols''. He also was a co-author of the Cahn–Ingold–Prelog priority rules. Ingold is regarded as one of the chief pioneers of physical organic chemistry.<ref>{{Cite journal | last1 = Saltzman | first1 = M. D. | title = The development of physical organic chemistry in the United States and the United Kingdom: 1919–1939, parallels and contrasts | doi = 10.1021/ed063p588 | journal = Journal of Chemical Education | volume = 63 | issue = 7 | pages = 588 | year = 1986 | bibcode = 1986JChEd..63..588S }}{{subscription required}}</ref><ref>{{cite book | author = Ingold, C. K. | title = Structure and Mechanism in Organic Chemistry | year = 1953 | publisher = Cornell University Press | location = Ithaca, New York | isbn = 0-8014-0499-1 | url-access = registration | url = https://archive.org/details/structuremechani0000ingo }}</ref><ref>{{cite journal | author = Ingold, Christopher K. | title = Principles of an Electronic Theory of Organic Reactions | journal = Chemical Reviews | year = 1934 | volume = 15 | issue = 2 | pages = 238–274 | doi=10.1021/cr60051a003}}</ref>
==Early life and education== thumb|RSC commemorative plaque at University College. Born in London to a silk merchant who died of tuberculosis when Ingold was five years old,<ref name="frs"/> Ingold began his scientific studies at Hartley University College at Southampton (now Southampton University) taking an external BSc in 1913 with the University of London. He then joined the laboratory of Jocelyn Field Thorpe at Imperial College, London, with a brief hiatus from 1918–1920 during which he conducted research into chemical warfare and the manufacture of poison gas with Cassel Chemical at Glasgow.<ref name="org_pioneer">{{Cite journal | last1 = Ridd | first1 = John | url=https://www.rsc.org/images/Historical%20profile_tcm18-138980.pdf | title = Historical Profile - Organic Pioneer | journal = Chemistry World | pages = 50–53| date = December 2008 }}</ref> Ingold received an MSc from the University of London and returned to Imperial College in 1920 to work with Thorpe.<ref>{{Cite journal | last1 = Ingold | first1 = C. K. | author-link = Christopher Kelk Ingold| title = Jocelyn Field Thorpe. 1872–1939 | doi = 10.1098/rsbm.1941.0020 | doi-access = free| journal = Obituary Notices of Fellows of the Royal Society | volume = 3 | issue = 10 | pages = 530–544| year = 1941 | jstor = 769165| s2cid = 178487429 }}</ref> He was awarded a PhD in 1918 and a DSc in 1921.
==Academic career== In 1924 Ingold moved to the University of Leeds where he spent six years as Professor of Organic Chemistry working alongside his wife, Dr. Edith Hilda Ingold (Usherwood). He returned to London in 1930, and served for 24 years as head of the chemistry department at University College London, from 1937 until his retirement in 1961.
During his study of alkyl halides, Ingold found evidence for two possible reaction mechanisms for nucleophilic substitution reactions. He found that tertiary alkyl halides underwent a two-step mechanism (S<sub>N</sub>1) while primary and secondary<ref>Absence of SN1 Involvement in the Solvolysis of Secondary Alkyl Compounds, T. J. Murphy, J. Chem. Educ.; 2009; 86(4) pp 519–24; (Article) doi: 10.1021/ed041p678 </ref> alkyl halides underwent a one-step mechanism (S<sub>N</sub>2). This conclusion was based on the finding that reactions of tertiary alkyl halides with nucleophiles were dependent on the concentration of the alkyl halide only. Meanwhile, he discovered that primary and secondary alkyl halides, when reacting with nucleophiles, depend on both the concentration of the alkyl halide and the concentration of the nucleophile.
Starting around 1926, Ingold and Robert Robinson carried out a heated debate on the electronic theoretical approaches to organic reaction mechanisms. See, for example, the summary by Saltzman.<ref>{{Cite journal | last1 = Saltzman | first1 = M. D. | title = The Robinson-Ingold controversy: Precedence in the electronic theory of organic reactions | doi = 10.1021/ed057p484 | journal = Journal of Chemical Education | volume = 57 | issue = 7 | pages = 484 | year = 1980 | bibcode = 1980JChEd..57..484S }}</ref>
Ingold authored and co-authored 443 papers.<ref>{{cite journal | author = Saltzman, Martin D. | title = C. K. Ingold's Development of the Concept of Mesomerism | journal = Bulletin for the History of Chemistry | year = 1996 | volume = 19 | pages = 25–32 | url=http://acshist.scs.illinois.edu/bulletin_open_access/num19/num19%20p25-32.pdf}}</ref> Notable students include Peter de la Mare, Ronald Gillespie and Ronald Nyholm.<ref name="Century">{{cite book |last1=Cambie |first1=R.C. |title=A century of chemistry at the University of Auckland 1883–1983 |last2=Davis |first2=B.R. |publisher=Percival |year=1983 |location=Auckland |pages=35–37}}</ref>
==Honours== In 1920, Ingold was awarded the British Empire Medal (BEM) for his wartime research involving "great courage in carrying out work in a poisonous atmosphere, and risking his life on several occasions in preventing serious accidents,"<ref>{{London Gazette |issue=31967 |date=6 July 1920 |page=7308 |supp=y |nolink=y}}</ref> though he subsequently never discussed the award or this period in his life.<ref name="org_pioneer"/>
Ingold was elected a Fellow of the Royal Society (FRS) in 1924.<ref>[https://www.rsc.org/images/Historical%20profile_tcm18-138980.pdf Chemistry World, Organic Pioneer, published December 2008]</ref> He received the Longstaff Medal of the Royal Society of Chemistry in 1951, the Royal Medal of the Royal Society in 1952, and was knighted in 1958.
The chemistry department of University College London is now housed in the Sir Christopher Ingold building, opened in 1969.
==Personal life== Ingold married Dr. Edith Hilda Ingold (Usherwood) in 1923. She was a fellow chemist with whom he collaborated. They had two daughters and a son, the chemist Keith Ingold.<ref>{{cite book | author = Nye, Mary Jo | author-link= Mary Jo Nye | title = From Chemical Philosophy to Theoretical Chemistry | year = 1994 | publisher = University of California Press | pages = 197–198 | url = https://books.google.com/books?id=z39bhlMAHMYC&q=classic+chemistry+ingold&pg=PA211 | isbn = 978-0-520-08210-6}}</ref>
==Death== Ingold died in London in 1970, aged 77.
==References== {{reflist}}
== Further reading == Dr. Malmberg's class: K.P. *{{cite book | author = Leffek, Kenneth T. | title = Sir Christopher Ingold: A Major Prophet of Organic Chemistry | year = 1996 | publisher = Nova Lion Press | isbn = 0-9680674-0-9}} **[http://jchemed.chem.wisc.edu/Journal/Issues/1997/jun/abs625_1.html Review of Leffek's book] by John D. Roberts *{{cite journal | author = Ridd, John | title = Organic Pioneer | journal = Chemistry World |date=December 2008 | volume = 5 | issue = 12 | pages = 50–53 | url=https://www.rsc.org/images/Historical%20profile_tcm18-138980.pdf}}
==External links== *[https://web.archive.org/web/20060310113032/http://www.chemistry.msu.edu/Portraits/PortraitsHH_Detail.asp?HH_LName=Ingold Biography at Michigan State University] *[http://www.chem.ucl.ac.uk/resources/history/people/ingold.html Biography] and [http://www.chem.ucl.ac.uk/resources/history/chemhistucl/hist19.html history] at University College London.
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{{DEFAULTSORT:Ingold, Christopher Kelk}} Category:British organic chemists Category:Academics of the University of Leeds Category:Academics of University College London Category:Knights Bachelor Category:Recipients of the British Empire Medal Category:Royal Medal winners Category:British fellows of the Royal Society Category:1893 births Category:1970 deaths Category:Alumni of the University of Southampton Category:Alumni of Imperial College London Category:Stereochemists Category:People from Edgware Category:Chemists of the University of Leeds Category:Chemists of University College London