UCL - a landmark in organic chemistry

University College London (UCL) has been awarded its second Royal Society of Chemistry (RSC) National Chemical Landmark for the contributions made by Sir Christopher Ingold in the development of physical organic chemistry during his 40-year career at the university's chemistry department. The award recognises Ingold, who from 1930-70 'pioneered our understanding of the electronic basis of structure, mechanism and reactivity in organic chemistry, which is fundamental to modern-day chemistry'. 

Professor David Price, UCL's vice-provost for research, accepted a commemorative blue plaque at a ceremony in November at UCL's chemistry building, which has carried Christopher Ingold's name since it opened in 1969. Speaking at the celebration of the life and work of Ingold, Professor John Ridd, a student of Ingold's at UCL, said his mentor's contributions to the teaching of modern chemistry 'moved it away from the study of the reactions and properties of molecules to an interpretive understanding of how and why reactions happen'. 

Ingold joined UCL from Leeds University in 1930. His theories on the electronic structure of organic compounds and the mechanisms of their reactions built on earlier ideas of Manchester University chemist Robert Robinson. At UCL Ingold formed a long and successful collaboration with Edward Hughes and their kinetic and mechanistic studies of the reactions of alkyl halides in solutions provided evidence for two possible pathways for nucleophilic substitution reactions: the two-step S_N1 mechanism favoured by most secondary and tertiary alkyl halides, the rate-determining step dependent only on alkyl halide concentration; and the S_N2 mechanism in which nucleophilic substitution for most primary alkyl halides occurs in one step, the rate of reaction being dependent on the concentrations of both reactants. Ingold's detailed studies of these mechanisms showed why the stereo-chemistry of the reaction product is dependent on the mechanistic pathway - the one-step process always resulting in inversion of stereochemistry about the reaction centre in the product. 

Through his work Ingold provided a new language for discussing reaction mechanisms in solution, introducing concepts, such as nucleophile, electrophile, inductive and resonance effects, and nomenclature such as S_N1, S_N2, E1 and E2, which now are a part of the everyday fabric of chemistry. 

In 1937 Ingold took over from George Frederick Donnan as head of department and remained on the UCL staff until his death in 1970. His textbook Structure and mechanism in organic chemistry is a cornerstone of organic chemistry, and other important work includes the coauthored Cahn-Ingold-Prelog priority rules used to name the stereoisomers of a molecule.  

The National Chemical Landmark scheme is part of the RSC's initiative to recognise major achievements in the chemical sciences and bring them to the public's attention. University College London received its first award in 2004 to mark the centenary of Sir William Ramsay's Nobel Prize in chemistry for his work on the isolation of the noble gases.