Calculation of ~(19)F NMR Chemical Shifts of Fluoroaromatics

Based on the comprehensive summarization and analysis of reported data of 19F NMR chemical shift,a empirical formula using parameters from 20 substitutents as variables to calculate 19F NMR chemical shifts of fluoroaromatics(δcal=-113.5+Δo+Δm+Δp+C) was derived with linear least-squares regression.A F-test was used to evaluate the formula obtained.The confidence limit was found to be 99.5%,average deviation 0.628 and standard deviation 4.720.The calculating errors for about 93.2% of the compounds were found to be less than 7.0(with relative errors of 0.7%).