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Structures of Carboxylic Acid Derivatives01:28

Structures of Carboxylic Acid Derivatives

Structure of Carboxylic Acid Derivatives
Carboxylic acid derivatives contain an acyl group attached to a heteroatom such as chlorine, oxygen, or nitrogen. The carbonyl carbon and oxygen are both sp2-hybridized with an unhybridized p orbital.
The three sp2 orbitals of the carbonyl carbon form three σ bonds, one each with the carbonyl oxygen, the α carbon, and the heteroatom, whereas the other two sp2 orbitals of the carbonyl oxygen are occupied by the lone pairs. Further, the unhybridized p...
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The relative stability of alkenes can be determined by comparing their heats of hydrogenation. The lower heat of hydrogenation indicates the more stable alkene.  The three main factors determining the relative stability of alkenes are i) the number of substituents attached to the double-bond carbon atoms, ii) hyperconjugation, and iii) the stereochemistry of the double bond.
Acetals and Thioacetals as Protecting Groups for Aldehydes and Ketones01:24

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Acid Halides to Esters: Alcoholysis01:12

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Updated: Jul 8, 2026

How to Stabilize Protein: Stability Screens for Thermal Shift Assays and Nano Differential Scanning Fluorimetry in the Virus-X Project
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Stability and structure studies on alisol a 24-acetate.

Bolat Makabel1, Yuying Zhao, Bin Wang

  • 1Department of Natural Medicines and the State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University Health Science Center, People's Republic of China.

Chemical & Pharmaceutical Bulletin
|January 8, 2008
PubMed
Summary
This summary is machine-generated.

Alisol A 24-acetate, a key compound in Traditional Chinese Medicine, is unstable in solvents. It transforms into alisol A 23-acetate and deacetylates to alisol A, particularly in protic solvents.

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Construction and Systematical Symmetric Studies of a Series of Supramolecular Clusters with Binary or Ternary Ammonium Triphenylacetates
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Construction and Systematical Symmetric Studies of a Series of Supramolecular Clusters with Binary or Ternary Ammonium Triphenylacetates
06:35

Construction and Systematical Symmetric Studies of a Series of Supramolecular Clusters with Binary or Ternary Ammonium Triphenylacetates

Published on: February 15, 2016

Area of Science:

  • Natural Product Chemistry
  • Pharmacognosy
  • Medicinal Chemistry

Background:

  • Alisol A 24-acetate is a primary active triterpenoid in Rhizoma Alismatis.
  • Rhizoma Alismatis is a well-established Traditional Chinese Medicine used for quality control.
  • Understanding the stability of active compounds is crucial for drug efficacy and standardization.

Purpose of the Study:

  • To investigate the stability of alisol A 24-acetate in various solvents.
  • To elucidate the structural transformations and degradation pathways of alisol A 24-acetate.
  • To report novel structural and spectroscopic data for related compounds.

Main Methods:

  • Stability studies of alisol A 24-acetate in different solvent systems.
  • Analysis of transformation products using spectroscopic techniques.
  • Single crystal X-ray diffraction and Nuclear Magnetic Resonance (NMR) spectroscopy.

Main Results:

  • Alisol A 24-acetate undergoes inter-transformation with alisol A 23-acetate in solvents.
  • Transformation rates are significantly higher in protic solvents compared to aprotic solvents.
  • Prolonged exposure to methanol leads to deacetylation, yielding alisol A from both acetates.

Conclusions:

  • This study is the first to report the structural transformation between alisol A 24-acetate, alisol A 23-acetate, and alisol A.
  • Solvent choice significantly impacts the stability and integrity of alisol A 24-acetate.
  • Novel single crystal X-ray structure of alisol A 24-acetate and NMR data for alisol A 23-acetate are presented.