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5-Fluoro-2-iodobenzoic acid is an important intermediate for the production of pharmaceuticals and agrochemicals. 

Step 1: 2-Amino-5-fluorobenzoic acid (25 g, 0.162 mol) was dissolved in 2N HCl solution (350 mL) and cooled to 0-5°C. At this temperature, a solution of sodium nitrite (11.2 g, 0.16 mol) in water (150 mL) was slowly added dropwise. After the dropwise addition was completed, the reaction mixture was continued to be stirred at 0-5°C for 90 min. Subsequently, the resulting diazonium salt solution was added dropwise to a solution of potassium iodide (53 g, 0.32 mol) and cuprous(I) iodide (15.2 g, 0.081 mol) in water (150 mL) that had been pre-cooled to about 5 °C. After completion of the dropwise addition, the reaction mixture was transferred to room temperature and stirred for 18 hours. The completion of the reaction was monitored by TLC (unfolding agent: EtOAc). At the end of the reaction, the mixture was filtered and the solid product was collected. The solid residue was diluted with methyl tert-butyl ether (MTBE, 500 mL), refluxed for 20 min and filtered. The filtrate was concentrated to give 5-fluoro-2-iodobenzoic acid (30 g, 75% yield) as a yellow solid. The product was characterized by 1H NMR (400 MHz, methanol-d4): δ 8.04-8.00 (m, 1H), 7.59-7.56 (m, 1H), 7.08-7.03 (m, 1H).

[1] Patent: WO2013/132376, 2013, A1. Location in patent: Page/Page column 151
[2] Chemistry--A European Journal, 2014, vol. 20, # 36, p. 11336 - 11339,4
[3] Patent: US2006/52378, 2006, A1. Location in patent: Page/Page column 146
[4] Patent: US2003/187014, 2003, A1
[5] Patent: WO2010/31, 2010, A1. Location in patent: Page/Page column 70