Conjugate Base Stability
Conjugate Base Stability - Related Videos
01:28
Stability of Conjugated Dienes
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2023
Introduction A comparison of the enthalpies of hydrogenation of dienes reveals that conjugated dienes release less heat on hydrogenation, rendering them more stable than their nonconjugated analogs. The two main factors contributing to the enhanced stability of conjugated systems are the delocalization of π electrons and the sp2 hybridization of the carbons forming the single bonds. Planar Conformers of Conjugated Dienes Conjugated dienes adopt two planar configurations, s-cis and s-trans,...
02:29
Relative Strengths of Conjugate Acid-Base Pairs
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2020
Brønsted-Lowry acid-base chemistry is the transfer of protons; thus, logic suggests a relation between the relative strengths of conjugate acid-base pairs. The strength of an acid or base is quantified in its ionization constant, Ka or Kb, which represents the extent of the acid or base ionization reaction. For the conjugate acid-base pair HA / A−, the ionization equilibrium equations and ionization constant expressions are Adding these two chemical equations yields the equation for the...
11:22
Cardiac Muscle-cell Based Actuator and Self-stabilizing Biorobot - PART 1
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Cited by 3 •
2017
In this two-part study, a biological actuator was developed using highly flexible polydimethylsiloxane (PDMS) cantilevers and living muscle cells (cardiomyocytes), and characterized. The biological actuator was incorporated with a base made of modified PDMS materials to build a self-stabilizing, swimming biorobot.
02:50
Conjugated Proteins
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2020
Simple proteins and protein complexes contain only amino acids. In contrast, many other proteins, called conjugated proteins, covalently bond with non-protein moieties. Nucleoproteins are protein complexes that contain nucleic acids, categorized as deoxyribonucleoproteins (DNPs) or ribonucleoproteins (RNPs) respectively. The nucleosome is a typical example of a DNP where nuclear DNA is associated with histone proteins. The major antigen for the Covid-19 virus SARS-CoV is an RNP that is critical...
01:19
Conjugation
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2025
Conjugation is a form of horizontal gene transfer that primarily occurs in bacteria and some archaea, promoting genetic diversity and adaptation. Bacteria can acquire resistance genes through conjugative plasmids, allowing them to survive antibiotic treatments that would otherwise be lethal. This process involves direct contact between cells through specialized structures such as the sex pilus and is mediated by conjugative plasmids, including the F (fertility) factor.Conjugation requires...
FAQs
Resonance stabilizes a conjugate base when its negative charge can delocalize across multiple atoms rather than remain concentrated in one location. This lowers the species’ energy and makes proton loss more favorable relative to a structure whose charge is localized. Comparing the extent of charge delocalization therefore helps explain acidity differences and predict which proton-transfer direction is favored.
An electronegative atom can better accommodate negative charge, increasing conjugate base stability. Electron-withdrawing effects also stabilize charge through the inductive effect, transmitted through the molecular framework. Greater s character in the orbital holding the charge provides another stabilizing factor. Considering these electronic features together helps distinguish acidity trends when resonance alone does not account for the observed preference.
Solvation can change the relative stability of conjugate bases by influencing how favorably the charged species interacts with its surrounding medium. Consequently, an electronic comparison made without considering solvation may not fully describe the observed acid–base behavior. Including solvation is especially important when using conjugate-base stability to interpret equilibria or compare proton-transfer outcomes under different conditions.
For a pair of acids, the acid that forms the more stable conjugate base generally has the greater tendency to lose a proton. Comparing charge dispersion, electronegative atoms, inductive withdrawal, orbital character, and solvation provides a basis for that judgment. This relationship connects molecular structure to acid–base equilibrium and helps identify the favored direction of proton transfer.
Begin by locating the negative charge in each conjugate base, then assess whether resonance can disperse it. Next, examine nearby electronegative atoms, electron-withdrawing inductive effects, and the s character of the charge-bearing orbital. Finally, consider solvation when relevant. This structured comparison supports predictions about relative acidity, equilibrium position, and proton-transfer preference without relying on a single factor.
Conjugate base stability helps guide reagent selection when a reaction depends on proton transfer. By comparing the bases produced or consumed during the process, chemists can anticipate which acid–base direction is more favorable and choose reagents accordingly. This reasoning supports reaction planning, particularly when selecting conditions intended to promote a desired proton-transfer step within a synthetic pathway.
Reaction mechanisms often contain proton-transfer steps whose feasibility depends on the relative stability of the conjugate bases involved. Evaluating charge delocalization, inductive effects, electronegativity, orbital character, and solvation can clarify why one pathway is favored over another. Applying these principles connects microscopic electronic structure with observable acidity trends and with the design of synthetic sequences.