The analysis of the high resolution spectrum of 1-(X-benzo [b] thienyl) ethyl acetate derivatives in several solvents is reported. It is noted that some spectra are deceptively simple. The coupling constants derived from different solvents are remarkably consistent. Also, it was shown that no appreciable differences in coupling constants derived before and after the addition of lanthanide shift reagents (LSR). Long-range coupling constants over five and four bonds were observed. A substantial downfield shift was observed at H3 and H4 arising from peri-interaction of the 3-H or 4-H and methane protons of ethylacetate group substituted at position 4 or 3 respectively. Lanthanide induced shifts (LIS) are discussed for the title compounds. The shift reagent leads to spectroscopic differentiation of the different protons.
HASSAN B AMIN ,IBRAHIM M AL-NAJJAR ,SALIM S AL-SHOWAMIN ,
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