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Hydroalumination adds an Al–H equivalent across an unsaturated bond. Syn and directed trans pathways give different alkenyl-aluminium geometries; protonolysis can preserve that stereochemical information.
A mechanistic correlation by which different reactant stereoisomers lead to different product stereoisomers.
A mechanistic correlation by which different reactant stereoisomers lead to different product stereoisomers.
G. N. Ramachandran coauthored analysis of the conformations accessible to polypeptide backbones. The Ramachandran plot expresses backbone geometry using two torsion angles and identifies regions restricted by steric contacts.
The plot converts a complex three-dimensional chain into a compact geometric test. It remains useful for interpreting protein structure, while allowed regions depend on residue identity and local context.[ref]
Stereochemistry of polypeptide chain configurations by G. N. Ramachandran and others. 1963, backbone torsions and steric restrictions
Portrait of G. N. Ramachandran
. University of Chicago Photographic Archive, apf1-10805, Hanna Holborn Gray Special Collections Research Center, University of Chicago Library. Source.C. Ramakrishnan helped investigate the geometry of polypeptide chains through backbone torsion angles. Steric restrictions rule out some angle combinations, providing a structural constraint that a protein model must satisfy in addition to its sequence.[ref]
Stereochemistry of polypeptide chain configurations by G. N. Ramachandran and others. 1963, backbone torsion angles and excluded configurations
V. Sasisekharan helped map geometrically allowed polypeptide backbone configurations. Representing the backbone by torsion angles exposes combinations excluded by steric overlap, connecting molecular geometry with restrictions on protein structure.[ref]
Stereochemistry of polypeptide chain configurations by G. N. Ramachandran and others. 1963, backbone torsion-angle representation and steric restrictions
Romain Melot investigated total synthesis strategies based on carbon–hydrogen bond activation. One sequence combines extensive bromination with selective removal of bromine, illustrating how temporary substitution can guide the preparation of a chosen aromatic substitution pattern.[ref]
Total Synthesis of (Nor)illudalane Sesquiterpenes Based on a C(sp3)-H Activation Strategy by Romain Melot and others. 2019, Scheme6: perbromination and selective HI debromination of 2,5-xylenol
Hydrolysis is a chemical reaction involving water that breaks a chemical bond. The free energy released by suitably coupled ATP hydrolysis can drive active transport; the available free energy depends on the actual composition and conditions.
Hydrolysis is a chemical reaction involving water that breaks a chemical bond. The free energy released by suitably coupled ATP hydrolysis can drive active transport; the available free energy depends on the actual composition and conditions.
Enolate alkylation forms a carbon–carbon bond by attack of an enolate carbon on an alkyl electrophile, commonly through an SN2 reaction. Solvent, counterion, aggregation and electrophile identity affect competition with oxygen alkylation.
A macrocycle containing triazole and other linking units. Appropriate inward-directed C–H donors can bind anions cooperatively; cavity size and molecular preorganization can produce strong halide selectivity.
Amar H. Flood coauthored research on shape-persistent triazolophane hosts that bind halide anions. The cavity size and electronic properties of the framework tune recognition through multiple carbon-hydrogen contacts.
This demonstrates that an anion-binding pocket need not rely only on conventional oxygen-hydrogen or nitrogen-hydrogen donors. Shape and the collective effect of several weaker contacts can produce selective molecular recognition.[ref]
Portrait of Amar H. Flood
. External portrait hosted by Indiana University Bloomington, Department of Chemistry. Source.An electrochemical capacitor storing charge through high-area electric double layers, pseudocapacitance, or a combination. Its device energy depends on usable voltage, inactive mass and rate capability as well as electrode capacitance.
An electrochemical capacitor storing charge through high-area electric double layers, pseudocapacitance, or a combination. Its device energy depends on usable voltage, inactive mass and rate capability as well as electrode capacitance.
Chain growth by successive olefin metathesis steps that open cyclic alkenes. Relief of ring strain can offset the loss of monomer translational entropy.
Robert H. Grubbs coauthored template-directed ring-closing metathesis research. Coordination to a template can bring reactive ends of a polyether-containing chain into an arrangement favourable for ring formation.
This connects catalysis with molecular preorganization: a template changes the accessible geometry, while a metathesis catalyst carries out bond reorganization.[ref]
Template-Directed Ring-Closing Metathesis: Synthesis and Polymerization of Unsaturated Crown Ether Analogs by Michael J. Marsella and others. Lithium-templated formation of unsaturated crown-ether analogues
Portrait of Robert H. Grubbs
. The Royal Society; author listed as Duncan.Hull. CC BY-SA 3.0, via Wikimedia Commons. Source. 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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