Synthesis
Synthesis of 16-bromohexadecanoic acid 2: To a 2 L three-necked round-bottomed flask equipped with a mechanical stirrer, a reflux condenser tube, and a nitrogen introduction tube was added 177 g (0.63 mol) of 16-hydroxyhexadecanoic acid 1. Subsequently, 1000 mL (5 mol) of 30% hydrogen bromide in acetic acid solution and 310 mL of concentrated sulfuric acid were added. The system was connected to sequential trapping devices, sequentially a sodium hydroxide particle trap, a 25% aqueous sodium hydroxide solution trap and a saturated sodium carbonate solution trap. The reaction mixture was stirred overnight at room temperature and subsequently heated to reflux for 6 hours. Upon completion of the reaction, the mixture was cooled and poured into ice water and the precipitated solid was vacuum filtered. After high vacuum drying, 196 g of 16-bromohexadecanoic acid 2 was obtained Yield: 88%; Purity: >95%; Melting point: 67-69 °C; DSC: 69.0 °C (sharp); IR (paraffin paste): 1700 cm1 (strong), 650 cm1 (strong); 1H NMR (200 MHz, CD2Cl2): δ 3.4 (t, J = 8 Hz, 2H), 2.3 (t, J = 8 Hz, 2H), 1.8 (m, 2H), 1.6 (m, 2H), 1.2 (br.s, 22H).
References
[1] Tetrahedron Letters, 1999, vol. 40, # 10, p. 2011 - 2014
[2] Tetrahedron, 2000, vol. 56, # 51, p. 9975 - 9984
[3] Patent: US5502226, 1996, A
[4] Journal of the Chemical Society, Perkin Transactions 1: Organic and Bio-Organic Chemistry (1972-1999), 1993, # 10, p. 1183 - 1190
[5] Helvetica Chimica Acta, 1929, vol. 12, p. 478
