Abstract: A novel and simple ¹H-NMR method for determination of enantiomeric purity, BETR, is studied. BETR (Broad Peak Elimination by T₂ Relaxation) method is one that eliminates the broad peak of chiral shift reagent by CPMG pulse sequence in the ¹H-NMR determination. In the application of this technique to the determination of enantiomeric purity of 2'-hydroxy-2-benzyIoxy-1.1'-binaphthyl (1), in the presence of Eu(hfc)₃, the results are as follows. Increasing the molar ratio of Eu(hfc) l,the resonance peaks of methene in R isomer shift to the lower rede faster than that in S isomers but the chemical shift difference between wo protons of methene in S isomer is greater than that in R isomer. Due to Bloch-Siegert effect, their value:are dependent on the magnetic field strengrh.

Key words: BETR method, Enantiomer, Chiral shift reagent, Chiral binaphthyl derivate, Bloch-Siegert effect