Christopher Kelk Ingold
Sir Christopher Kelk Ingold FRS (28 October 1893 – 8 December 1970) was a British
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...

A chemist is a scientist trained in the study of chemistry. Chemists study the composition of matter and its properties such as density and acidity. Chemists carefully describe the properties they study in terms of quantities, with detail on the level of molecules and their component atoms...

 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
A nucleophile is a species that donates an electron-pair to an electrophile to form a chemical bond in a reaction. All molecules or ions with a free pair of electrons can act as nucleophiles. Because nucleophiles donate electrons, they are by definition Lewis bases.Nucleophilic describes the...

, electrophile
In general electrophiles are positively charged species that are attracted to an electron rich centre. In chemistry, an electrophile is a reagent attracted to electrons that participates in a chemical reaction by accepting an electron pair in order to bond to a nucleophile...

, inductive and resonance effects, and such descriptors as SN1
SN1 reaction
The SN1 reaction is a substitution reaction in organic chemistry. "SN" stands for nucleophilic substitution and the "1" represents the fact that the rate-determining step is unimolecular...

, SN2
SN2 reaction
The SN2 reaction is a type of nucleophilic substitution, where a lone pair from a nucleophile attacks an electron deficient electrophilic center and bonds to it, expelling another group called a leaving group. Thus the incoming group replaces the leaving group in one step...

, E1, and E2. He also was a co-author of the Cahn–Ingold–Prelog priority rules. Ingold is regarded as one of chief pioneers of physical organic chemistry
Physical organic chemistry
Physical organic chemistry is the study of the interrelationships between structure and reactivity in organic molecules. It can be seen as the study of organic chemistry using tools of physical chemistry such as chemical equilibrium, chemical kinetics, thermochemistry, and quantum chemistry...


Scientific work

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
University of London
-20th century:Shortly after 6 Burlington Gardens was vacated, the University went through a period of rapid expansion. Bedford College, Royal Holloway and the London School of Economics all joined in 1900, Regent's Park College, which had affiliated in 1841 became an official divinity school of the...

. After a brief time with Imperial College, London and some war service, as a scientist, Ingold earned an MSc degree, again with the University of London. He returned to Imperial College for work with Jocelyn Field Thorpe
Jocelyn Field Thorpe
Sir Jocelyn Field Thorpe FRS was an English chemist who discovered the Thorpe reaction and the Thorpe-Ingold effect....

, and was awarded a PhD
Doctor of Philosophy
Doctor of Philosophy, abbreviated as Ph.D., PhD, D.Phil., or DPhil , in English-speaking countries, is a postgraduate academic degree awarded by universities...

 in 1918 and a DSc
Doctor of Science
Doctor of Science , usually abbreviated Sc.D., D.Sc., S.D. or Dr.Sc., is an academic research degree awarded in a number of countries throughout the world. In some countries Doctor of Science is the name used for the standard doctorate in the sciences, elsewhere the Sc.D...

 in 1921.

Ingold married Dr. Hilda Usherwood, a fellow chemist with whom he collaborated, in 1923. They had two daughters and a son, the chemist Keith Ingold
Keith Usherwood Ingold
Keith Usherwood Ingold OC FRS FRSCan FRSE is a British chemist.He was born in to Sir Christopher Ingold and Dr. Hilda Usherwood, and studied for a BSc in Chemistry at the University of London, completing his degree in 1949. He continued his higher education with a PhD in chemistry at Oxford...


In 1924, Ingold moved to Leeds University
University of Leeds
The University of Leeds is a British Redbrick university located in the city of Leeds, West Yorkshire, England...

 where he spent six years as Professor of Organic Chemistry. He returned to London in 1930, and served for 24 years as Head of the chemistry department at University College London
University College London
University College London is a public research university located in London, United Kingdom and the oldest and largest constituent college of the federal University of London...

, from 1937 until his retirement in 1961.

During his study of alkyl halide
The haloalkanes are a group of chemical compounds derived from alkanes containing one or more halogens. They are a subset of the general class of halocarbons, although the distinction is not often made. Haloalkanes are widely used commercially and, consequently, are known under many chemical and...

s, Ingold found evidence for two possible reaction mechanisms for nucleophilic substitution reactions. He found that most secondary and tertiary alkyl halides underwent a two-step mechanism (SN1) while most primary alkyl halides underwent a one-step mechanism (SN2). This conclusion was based on the finding that reactions of most secondary and tertiary alkyl halides with nucleophiles were dependent on the concentration of the alkyl halide only. Meanwhile he discovered that primary 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.

Sir Christopher Ingold received the Longstaff Medal of the Royal Society of Chemistry
Royal Society of Chemistry
The Royal Society of Chemistry is a learned society in the United Kingdom with the goal of "advancing the chemical sciences." It was formed in 1980 from the merger of the Chemical Society, the Royal Institute of Chemistry, the Faraday Society and the Society for Analytical Chemistry with a new...

 in 1951, the Royal Medal
Royal Medal
The Royal Medal, also known as The Queen's Medal, is a silver-gilt medal awarded each year by the Royal Society, two for "the most important contributions to the advancement of natural knowledge" and one for "distinguished contributions in the applied sciences" made within the Commonwealth of...

 of the Royal Society
Royal Society
The Royal Society of London for Improving Natural Knowledge, known simply as the Royal Society, is a learned society for science, and is possibly the oldest such society in existence. Founded in November 1660, it was granted a Royal Charter by King Charles II as the "Royal Society of London"...

 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.

Further reading

    • Review of Leffek's book by John D. Roberts
      John D. Roberts
      John Dombrowski Roberts is an American chemist. He has made contributions to the integration of physical chemistry, spectroscopy and organic chemistry for the understanding of chemical reaction rates....

External links

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