Conjugate Acid Stability
Conjugate Acid 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...
10:42
A Tripeptide-Stabilized Nanoemulsion of Oleic Acid
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2019
This protocol describes an efficient method to synthesize a nanoemulsion of an oleic acids-platinum(II) conjugate stabilized with a lysine-tyrosine-phenylalanine (KYF) tripeptide. The nanoemulsion forms under mild synthetic conditions via self-assembly of the KYF and the conjugate.
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
Phase II Reactions: Sulfation and Conjugation with α-Amino Acids
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2025
Sulfation and α-amino acid conjugation are two critical biotransformation reactions in drug metabolism. Sulfation, a phase II biotransformation reaction, involves adding a polar sulfate group to a drug, enhancing its water solubility and promoting excretion. This process can either co-occur with or occur independently of glucuronidation. Nonmicrosomal sulfotransferase enzymes catalyze the process. The reaction involves 3'-phosphoadenosine-5'-phosphosulfate or PAPS coenzyme activation, sulfur...
FAQs
A protonated species becomes more stable when its positive charge is accommodated effectively rather than concentrated in an unfavorable location. Resonance can spread the charge across multiple atoms, while inductive effects influence charge distribution through nearby groups. Evaluating these features helps explain why related protonated species differ in persistence and why their corresponding bases show different acid–base behavior.
These factors affect the location and distribution of positive charge in different ways. Resonance delocalizes charge across a connected structure, inductive effects transmit electronic influence through neighboring groups, and atom electronegativity affects how comfortably an atom accommodates charge. Comparing all three provides a more reliable stability assessment than considering any single structural feature alone.
Solvation can stabilize a protonated species by interactions with the surrounding medium, so the same acid–base pair may behave differently under different conditions. A stability comparison should therefore consider not only the molecular structure but also how effectively the medium solvates the charged species. This is especially relevant when interpreting acid–base behavior in aqueous and organic systems.
Proton-transfer equilibria tend to favor formation of the more stable acid–base pair. To predict direction, compare the stability of the protonated species on both sides and then consider the associated bases and acids together. This approach connects molecular charge accommodation with observable reaction preference, helping explain why some proton-transfer processes proceed more readily than others.
First identify where the positive charge resides in each protonated species. Next assess resonance delocalization, inductive effects, atom electronegativity, and solvation by the relevant medium. Finally compare the overall charge accommodation and use that ranking to infer relative basicity and likely proton-transfer direction. Keeping the same environmental assumptions for both species makes the comparison more consistent.
The concept is useful whenever chemists need to compare basicity, anticipate proton-transfer reactions, or interpret the behavior of functional groups. In organic systems, structural charge effects help organize comparisons among related compounds. In aqueous systems, solvation becomes an important part of the analysis. Together, these considerations support predictions about equilibrium preference and acid–base reactivity.