Question

how we detect chirality , enantiomer, diaenatiomers with NMR H proton?

Answer 1

Enantiomers cannot be deted by NMR spectroscopy, but can be by chiral agents and by optical rotation (equal and exactly opposite positive and negative rotation values).

chirality and diastereomers are detected by performing a sequence of 1H NMR 1D and 2D experiments and analyzing the data by a professional or an experienced person is necessary.

The experiments required are 1D-1H NMR , 1D-13C NMR, 1D-NOESY (Laboratory Frame Nuclear Overhauser Spectroscopy), 2D-COSY (Correlation Spectroscopy), 2D-TOCSY (Total Correlation Spectroscopy), 2D-NOESY and 2D-ROESY (Rotatory Frame Nuclear Overhauser Spectroscopy). Mainly NOESY & ROESY gives spatial proximity of protons nearby less than 5 Angstroms distance. All the NMR data coupled with molecular modelling using steepest and conjugate gradient algorithms, looking for global minima structure and comparing with NMR spectral data is enough to identify chirality and diastereomers.

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