The 5-(trifluoromethyl)isophthalic acid (209) was synthesised using a previously reported method. 3-Methyl-5-(trifluoromethyl)benzoic acid (206, 1.00158 g, 1 equiv.) was suspended in H2O (100 mL) and stirred at r.t. while KMnO4 (3.10907 g, 4.01 equivs.) was added. The reaction mixture was then heated to reflux (100 °C, 373.15 K) over 16 h. The hot reaction mixture was then carefully filtered through a layer of celite (2-3 cm thick), and the filtrate was collected and allowed to cool. Once at r.t., the filtrate was acidified by adding conc. HCl(aq) (32%) with stirring to protonate the oxidised product. Slowly, a white solid precipitated from the solution, which was separated after stirring for a further 45 min, washed with H2O (2×10 mL), and then dried in vacuo for 12 h. The solid was then redissolved in acetone and extruded through a PTFE 0.22 μM pore syringe filter to remove the insoluble brown impurities. The acetone filtrate was then evaporated under reduced pressure and dried in vacuo for 12 h to afford the white solid of 209 in a yield of 0.65330 g (57%). The General synthetic procedure for the Isophthaloyl Chloride Intermediates The isophthaloyl chloride intermediates were synthesised following a previously reported method. The reaction flask was charged with the respective isophthalic acid starting material (1 equiv.), and the atmosphere was purged with N2(g) before CH2Cl2 (25 mL) was added and further degassed with N2(g) and DMF (2 drops, Cat.) was added. The reaction mixtures were allowed to stir for 10 min to ensure the homogeneity of the mixture before oxalyl chloride (2.2 equivs.) was added. The reaction was stirred for a further 10 min to allow the potential evolution of HCl(g) to be monitored, after which the reaction was heated to reflux (40 °C, 313.15 K). During each reaction, the isophthalic acids were observed to dissolve as the respective isophthaloyl chloride intermediates formed, which was indicated by a changed colour and the disappearance of the starting material suspended in solution.