Step 2) Synthesis of 5-(2-bromophenyl)-1H-tetrazole: A mixture of 2-bromobenzonitrile (10.0 g, 0.055 mol), sodium azide (3.9 g, 0.060 mol), ammonium chloride (3.2 g, 0.060 mol), and N,N-dimethylformamide (DMF, 90 mL) was heated for 18 hours at 100 °C. After completion of the reaction, the mixture was concentrated, dissolved in water and adjusted to alkaline (pH 9) with 1N potassium hydroxide (KOH) solution. The aqueous phase was extracted with ether (the organic phase was discarded) and subsequently acidified with 2N hydrochloric acid (HCl). The precipitate precipitated was collected by filtration to afford 9.1 g (73% yield) of the target product, 5-(2-bromophenyl)-1H-tetrazole, as an off-white solid with melting point 179-181 °C. The 1H NMR (DMSO-d6) data were as follows: δ 7.56 (m, 2H), 7.69 (dd, J = 7.0 Hz, 2.1 Hz, 1H), 7.86 (dd, J = 7.6 Hz, 1.3 Hz, 1H).
