Hydrochloric Acid → 2-Iodo-2-nonene

Participants

Reaction Conditions

Reaction Steps

To a mixture of 0.24 g (8.0 mmol) of 80% sodium hydride and 8 mL of dry diglyme was added at 0° C. 3.75 mL (7.50 mmol) of 2.0M trimethylaluminum in hexane. The reaction mixture was warmed to room temperature, stirred for 2 hours, and then was filtered under argon through a medium glass frit. The hexane contained in the filtrate was removed under reduced pressure (25° C., 30 torr), and the clear solution of sodium trimethylaluminum hydride obtained was treated at 0° C. with 0.72 g (5.0 mmol) of 1-chloro-1-octyne and 0.70 mL (5.0 mmol) of n-heptane as an internal GC standard. The solution was stirred for one hour at 0° C. (hydrolysis of an aliquot at this point revealed by GC 89% trans-1-chloro-1-octene and 11% 1-octyne) and to the solution was added 0.40 g (7.5 mmol) of sodium methoxide. The mixture was then warmed to 50° C. and stirred overnight. Hydrolysis and GC analysis of an aliquot showed 69% cis-2-nonene (containing <0.5% trans-2-nonene) and 31% 1-octyne. The reaction was cooled to -78° C. and treated with a solution of 1.59 g (6.25 mmol) of iodine in 5 mL of diglyme. After warming the reaction mixture to 25° C., GC examination of an aliquot showed complete iodination had occurred, as no residual cis-2-nonene was present after hydrolysis. However, due to the formation of some 1-iodo-1-octyne, the reaction solution was additionally treated with 1.0 mL (2.0 mmol) of 2.0M trimethylaluminum in hexane, which after 24 hours at room temperature had converted all 1-iodo-1-octyne into 1-octyne (after protonolysis), thereby simplifying the isolation procedure. The reaction mixture was slowly poured into a mixture of 3N HCl and pentane. The aqueous layer was extracted with pentane and the combined organic phase was washed sequentially with 3N HCl, saturated NaHCO3, 20% Na2SO3, and saturated NaCl. Concentration and short-path distillation provided 0.79 g (63%) of the 2-iodo-2-nonene: bp=45./0.1 torr; IR (neat) 3020 (w), 2950 (s), 2920 (s), 2850 (s), 1638 (m), 1465 (m), 1455 (m), 1385 (m), 1135 (m), 1060 (m) cm-1 ; 1H--NMR (CDCl3, TMS) 0.90 (t, 3H), 1.2-1.5 (br s, 8H), 2.05 (m, 2H), 2.35 (d, J=1.5 Hz, 3H), 6.15 (tq, J=7.2, 1.5 Hz, 1H).

Provenance & Evidence