Which one of the given compounds is a stronger acid and why?
CH$_2$FCH$_2$COOH or CH$_3$CHFCH$_2$COOH
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Fluorine is a highly electronegative element. The closer it is to the carboxyl group, the stronger the acid due to the electron-withdrawing inductive effect.
CH$_3$CHFCH$_2$COOH is the stronger acid. This is due to:
- The fluorine atom in CH$_3$CHFCH$_2$COOH, being more electronegative than hydrogen, exerts an inductive effect that withdraws electron density from the carboxyl group (-COOH). This stabilizes the conjugate base (carboxylate anion, RCOO$^-$), facilitating proton (H$^+$) release and increasing acidity.
- Conversely, in CH$_2$FCH$_2$COOH, the fluorine atom is positioned further from the carboxyl group, leading to a diminished electron-withdrawing effect. This results in less stabilization of the carboxyl group, rendering CH$_2$FCH$_2$COOH a weaker acid compared to CH$_3$CHFCH$_2$COOH.
