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Gilbert Stork developed strategies for selective organic synthesis, including enamine alkylation. An enamine provides a way to form a new carbon–carbon chemical bond at a chosen position, linking a temporary nitrogen-containing intermediate with the construction of a carbon skeleton. His oral history describes this work alongside polyene cyclization and the synthesis of natural products.[ref]
Arthur Michael reported the addition of stabilized carbon nucleophiles to unsaturated esters in 1887, work associated with the Michael addition. The reaction forms a carbon-carbon bond through conjugate addition to an electron-poor unsaturated system.
The nucleophile attacks a carbon remote from the carbonyl oxygen while the conjugated framework distributes the resulting electron density. This gives organic synthesis a way to extend a carbon skeleton while retaining useful carbonyl functionality.[ref]
https://doi.org/10.1002/prac.18870350136. Original 1887 paper, Journal für Praktische Chemie 35, pages 349–356
George Wheland investigated aromatic substitution using quantum mechanics. His 1942 paper analyses the orientation of substituents in aromatic molecules, connecting electronic structure with the positions favoured in a substitution reaction.
The Wheland intermediate is an arenium ion formed by electrophilic addition to an aromatic ring. Comparing stabilization of alternative intermediates helps explain substituent effects, while a complete mechanism must also account for the relevant transition states.[ref]
https://doi.org/10.1021/ja01256a047. A Quantum Mechanical Investigation of the Orientation of Substituents in Aromatic Molecules, 1942, pages 900–908
Jakob Meisenheimer investigated reactions of aromatic nitro compounds, including the chemistry now associated with the Meisenheimer complex. Such a complex is a nonaromatic addition product in which a nucleophile has added to an electron-poor aromatic system.
Electron-withdrawing substituents can stabilize the resulting anionic framework. This makes the intermediate useful for understanding an addition-elimination pathway of nucleophilic aromatic substitution.[ref]
https://doi.org/10.1002/jlac.19023230205. Ueber Reactionen aromatischer Nitrokörper, 1902, pages 205–246
Martin Karplus helped develop computational descriptions of chemical reactions and biomolecular motion. His work on molecular dynamics used calculated interatomic forces with Newton's laws of motion to follow the motion of atoms in a protein. Such trajectories connect an assumed molecular potential energy with time-dependent molecular behaviour.[ref]
https://www.nobelprize.org/prizes/chemistry/2013/karplus/biographical/. Autobiography: The First Molecular Dynamics Simulation of a Biomolecule
Portrait of Martin Karplus
. Bengt Nyman. CC BY 2.0, via Wikimedia Commons. Source.Robert Sidney Cahn coauthored the molecular-chirality system associated with the Cahn-Ingold-Prelog priority rules. The system assigns ordered priorities to substituent paths so that a three-dimensional arrangement can receive a reproducible descriptor.
Priority is a naming convention based on specified structural comparisons, not a ranking of chemical reactivity. Distinguishing those questions lets the same stereochemical language be applied across very different molecular families.[ref]
https://doi.org/10.1002/anie.196603851. Specification of Molecular Chirality, 1966: general system and extensions
Christopher Kelk Ingold helped establish the kinetic and mechanistic framework of organic chemistry, including the distinction between SN1 and SN2 substitution. The two mechanisms connect reaction-rate dependence with different sequences of bond breaking and bond formation.[ref]
https://www.ucl.ac.uk/mathematical-physical-sciences/chemistry/about-us/history-department. Department history: Christopher Ingold and the development of reaction mechanisms
With Robert Sidney Cahn and Vladimir Prelog, Christopher Kelk Ingold also developed a systematic specification of molecular chirality. The Cahn-Ingold-Prelog priority rules separate ranking substituents from describing their spatial arrangement.[ref]
https://doi.org/10.1002/anie.196603851. Specification of Molecular Chirality, 1966
Vladimir Prelog helped formulate the Cahn-Ingold-Prelog priority rules for specifying molecular chirality. Ranking the groups attached to a stereogenic centre makes it possible to assign a reproducible stereochemical descriptor. A descriptor records configuration through a stated convention, rather than the sign of a sample's measured optical rotation.[ref]
Specification of Molecular Chirality by Robert Sidney Cahn and others. Cahn, Ingold and Prelog, Specification of Molecular Chirality, 1966
Portrait of Vladimir Prelog
. ETH Zürich / ETH-Bibliothek Zürich, Bildarchiv; cropped by Sebastian Wallroth. CC BY-SA 3.0, via Wikimedia Commons. Source.Hugh Felkin contributed to the model now called the Felkin-Anh model, used to reason about facial selectivity in additions to carbonyl compounds with an adjacent stereogenic centre.
The model relates the sizes and orientations of substituents to the approach of a nucleophile. Explicitly comparing an open pathway with a chelated pathway explains why changing a metal reagent or solvent can change the product diastereoselectivity.[ref]
Felkin-Anh and Cram Chelate by University of Windsor. Pages 1–2, stereochemical models and chelation contrast
Nguyễn Trọng Anh is associated with the Felkin-Anh model of stereoselective nucleophilic addition to a carbonyl beside a stereogenic centre. The model connects substrate conformation and electronic interactions with the preferred face of attack.
Its usefulness is conditional: an open, non-chelating pathway can favour a different product from a metal-chelated pathway. Comparing these possibilities makes the model a mechanistic prediction under specified conditions rather than a universal stereochemical rule.[ref]
Hans-Beat Bürgi coauthored the structural-correlation work associated with the Bürgi-Dunitz trajectory. Comparing close nucleophile-carbonyl contacts in crystal structures helps identify a preferred oblique approach to a carbonyl carbon.
The characteristic Bürgi-Dunitz angle connects three-dimensional geometry with orbital overlap and repulsion. It is a useful trend for understanding nucleophilic addition, while steric constraints and molecular environment can change the accessible path.[ref]
https://doi.org/10.1021/ja00796a058. Geometrical reaction coordinates II: nucleophilic addition to a carbonyl group, 1973
Jack D. Dunitz used X-ray diffraction to investigate molecular structure, motion, and reaction paths. His work with Hans-Beat Bürgi relates structural correlations among molecules to possible trajectories of nucleophilic addition at a carbonyl group.
A set of static structures can sample geometries resembling different stages of bond formation. This provides experimental constraints on a reaction path, although each crystal is not itself a time-resolved frame of one reacting molecule.[ref]
https://doi.org/10.1021/ja00796a058. Geometrical reaction coordinates II: nucleophilic addition to a carbonyl group, 1973
Linkage isomerization changes which atom of an ambidentate ligand is bound to a central atom. Its rate depends on a reaction barrier, whereas the final equilibrium depends on relative free energies.
Ellika Nordin coauthored crystal-structure comparisons of nitrito- and nitropentaamminecobalt(III) salts. The structures distinguish coordination through oxygen from coordination through nitrogen.
This is linkage isomerism: the same ligand composition can bind through different donor atoms. Structural evidence from a solid identifies the coordinated form, while solution interconversion requires separate kinetic evidence.[ref]
Nitrito-Nitro Linkage Isomerization in the Solid State. 2. A Comparative Study of the Structures of Nitrito- and Nitropentaamminecobalt(III) Dichloride by Ingmar Grenthe and Ellika Nordin. Research topic and author attribution in the primary publication
Phosphine is . Its abundance in giant-planet observable atmospheres can depend on transport from deeper layers faster than local chemical destruction.
Paul S. Bagus coauthored calculations revisiting metal-phosphine bonding. The analysis separates sigma donation, pi acceptance, and the proposed role of phosphorus d orbitals in zerovalent metal complexes.
These distinctions explain why calling a phosphine simply a strong ligand loses information. Donor and acceptor interactions are separate components of the bonding problem, and an orbital calculation is not a universal experimental ranking of ligand strength.[ref]
Metal-phosphine bonding revisited. σ-Basicity, π-acidity, and the role of phosphorus d orbitals in zerovalent metal-phosphine complexes by Gianfranco Pacchioni and Paul S. Bagus. Research topic and author attribution in the primary publication
Theodore L. Brown coauthored a study of cis labilization in six-coordinate metal carbonyl compounds. The work distinguishes isotope-exchange observations from the geometry of substitution products.
A polymer with an alternating phosphorus–nitrogen backbone and typically two substituents at phosphorus. Polar bonding and negative hyperconjugation differ from a continuously conducting conjugated carbon backbone.
Pinned article: Introduction to the OurBigBook Project
Welcome to the OurBigBook Project! Our goal is to create the perfect publishing platform for STEM subjects, and get university-level students to write the best free STEM tutorials ever.
Everyone is welcome to create an account and play with the site: ourbigbook.com/go/register. We belive that students themselves can write amazing tutorials, but teachers are welcome too. You can write about anything you want, it doesn't have to be STEM or even educational. Silly test content is very welcome and you won't be penalized in any way. Just keep it legal!
Intro to OurBigBook
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This feature makes it possible for readers to find better explanations of any topic created by other writers. And it allows writers to create an explanation in a place that readers might actually find it.
Figure 1. Screenshot of the "Derivative" topic page. View it live at: ourbigbook.com/go/topic/derivativeVideo 2. OurBigBook Web topics demo. Source. - local editing: you can store all your personal knowledge base content locally in a plaintext markup format that can be edited locally and published either:This way you can be sure that even if OurBigBook.com were to go down one day (which we have no plans to do as it is quite cheap to host!), your content will still be perfectly readable as a static site.
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Figure 3. Visual Studio Code extension installation.
Figure 5. . You can also edit articles on the Web editor without installing anything locally. Video 3. Edit locally and publish demo. Source. This shows editing OurBigBook Markup and publishing it using the Visual Studio Code extension. 
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