Undecylenic Acid → 1-Dodecyne

Participants

Reaction Steps

The procedure for the bromination of 1-dodecene was essentially identical to that for 10-undecenoic acid (Step A), and was carried out on a 0.54 mol scale. Dehydrohalogenation was likewise carried out as in Step A using 250 g of 85% KOH (3.78 mol) and heating under reflux for 22 hours in 1.4 L ethanol. The product was isolated by pouring the cooled reaction mixture into 3L of ice-water slush and extracting with ether. The ether layers were washed and dried as before, evaporated, and the residue distilled. The fraction bp 103-113/25 Torr contained the product (36 g, 40%), which was characterized by spectral data: nmr (CDCl3) 0.9 τ(m, 3 H, CH3), 1.3(m, 16 H, CH2), 1.91(t, J=2.5 Hz, 1H, ≡CH), 2.18 (m, 2H, ≡CCH2); IR (film) 3350 (ν≡CH), 2150(νC≡C).

Provenance & Evidence