Answer to Question #328621 in Organic Chemistry for Steve

Question

Find the order of decreasing acid strength between CH3CF2COOH, CH3CHClCOOH, CH2ClCH2COOH, and CH3CH2COOH

Answer 1

Any group that decreases negative charge on carboxylate ion stabilises it and increases acidic character of the carboxylic acid. Halogens are electron withdrawing groups and their effect is maximum when they are present in the alpha position. Fluorine electron withdrawing ability is greater than that of chlorine.

CH3CF2COOH (most acidic) > CH3CHClCOOH > CH2ClCH2COOH > CH3CH2COOH (least acidic)