研究目的
Investigating the absolute configurations of naturally occurring [5]- and [3]-ladderanoic acids through isolation, chiroptical spectroscopy, and crystallography.
研究成果
The absolute configurations of naturally occurring [5]- and [3]-ladderanoic acids were determined to be R at the site of side-chain attachment. This was confirmed through multiple methods, including comparison of experimental and predicted specific rotations, Raman optical activity spectra, and X-ray crystallography.
研究不足
The study faced challenges in separating the [3]- and [5]-ladderanoic acids and their derivatives. The computational predictions overestimated the magnitude of specific rotations, and the conformational mobility complicated both calculations and crystal production.
1：Experimental Design and Method Selection
The study involved the isolation of ladderanoic acids from anammox bioreactor biomass, separation by HPLC, and determination of absolute configurations using quantum chemical methods, chiroptical spectroscopy, and X-ray crystallography.
2：Sample Selection and Data Sources
Biomass was obtained from an anammox process at a wastewater treatment plant. The samples were treated to convert ladderane esters to free acids, followed by extraction and purification.
3：List of Experimental Equipment and Materials
HPLC system (Beckman Coulter), polarimeter (Autopol IV), ChiralRAMAN spectrometer, ChiralIR spectrometer, Rigaku Oxford Diffraction Supernova diffractometer.
4：Experimental Procedures and Operational Workflow
The procedure included acid treatment of biomass, Soxhlet extraction with CH2Cl2, purification by column chromatography, preparation of phenacyl esters, and their separation by HPLC. Specific rotations, Raman optical activity, and vibrational circular dichroism spectra were measured.
5：Data Analysis Methods
Quantum chemical predictions were used to compare with experimental specific rotations and spectra. X-ray crystallography was employed to confirm absolute configurations.
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