If too impure as seen by the NMR spectrum, then dissolve it in 10 volumes of pentane, shake with cold NaHCO3 (3 x 500mL), then 1.5M HCl (200mL) and aqueous NaHCO3 (200mL) again, dry (Na2SO4), filter, evaporate and distil it through a short Vigreux column (p 11). 1H NMR: (CDCl3) : 0.21 (s, 9H), 1.55 (m, 2H), 1.69 (m, 2H), 2.05 (br d, 4H) and 4.88 (br s, 1H). GLPC in a 6ft x 1/8inch with 3% SP2100 on 100-120 mesh Supelcoport column should give one peak. Store dry. [For the cyclohexene analogue see Varghese et al. Org Synth Coll Vol VIII 460 1993.]