Hydrogen Bromide → 1-(2-Ethyl-butyl)-cyclohexanecarboxylic acid

Participants

Reaction Steps

A mixture of 1-(2-Ethyl-butyl)-cyclohexanecarboxylic acid isopropyl ester (10 g, 39.4 mmol) and sodium iodide (886 mg, 5.91 mmol) in AcOH (80 mL) was stirred 50 min at room temperature and then heated to 100° C. 48% aq. HBr (30 mL, 265 mmol) was added dropwise over 30 min. and the reaction mixture was stirred 28 h at 100° C. The cooled reaction mixture was diluted with DCM (120 mL) and ice-water (120 mL). The organic phase was separated and washed with diluted aq. NaCl. The aqueous phases were extracted with another portion of DCM. The organic phases were combined, dried over sodium sulfate and concentrated. The residue (9.1 g) was taken up in 4N NaOH and ice (30 g). The alkaline solution (pH 12) was extracted with DCM (2×50 mL) and made acidic to pH 1 using aq. H2SO4. Extraction with DCM (3×100 mL), washing with diluted aq. NaCl, drying over sodium sulfate and evaporation afforded 7.84 g (94%) 1-(2-ethyl-butyl)-cyclohexanecarboxylic acid, purity 99.3% (GC area, after derivatization with diazomethane). 1H-NMR (CDCl3, 300 MHz): ppm 0.81 (t, 6H), 1.15-1.65 (m, 15H), 2.05-2.15 (m, 2H), 12 (broad s, 1H).

Provenance & Evidence