Methyl hexanoate → Hexanoic acid, hydrazide

Under nitroqen, a solution of 262 g (8 2 mol) of anhydrous hydrazine in 1300 mL of methanol was cooled to 0° C. and treated with 885 g (6.8 mol) of methyl caproate. The reaction was allowed to warm to ambient temperature and stir overnight prior to stirring at reflux for 7 h. The reaction was concentrated in vacuo; recrystallization from toluene gave 707 g (80%) of caproic acid hydrazide as a colorless solid: mp 72.5°-73.9° C.; NMR (CDCl3) δ 0.82 (t, J=7 Hz, 3H), 1.15-1.33 (m, 4H), 1.51-1.64 (m, 2H), 2.10 (t, J=7 Hz, 2H), 3.91 (br s, 2H), 7.56 (br s, 1H). A 5.0 g (39 mmol) sample of the hydrazide was dissolved in 40 mL of methanol and treated with 11.2 g (78 mmol) of ethyl iminocaproate [P. Reynaud and R. C. Moreau, Bull. Soc., Chim. France, 2997 (1964)-which. was only about 50% pure by NMR] under nitrogen. The reaction was stirred at reflux for 2 days and concentrated in vacuo. Purification by silica gel chromatography (Waters Prep-500A) using ethyl acetate/hexane (48:52) gave 7.56 g (92%) of 3,5-dipentyl-1H-1,2,4-triazole as a colorless solid: mp 66°-68° C.; NMR (CDCl3) δ 0.88 (t, J=7 Hz, 6H), 1.24-1.41 (m, 8H), 1.66- 1.81 (m, 4H), 2.72 (t, J=7 Hz, 4H); MS (FAB) m/e (rel intensity) 210 (100), 166 (14); HRMS. Calcd for M+H: 210.1970. Found: 210.1964.