Sulfuric Acid → (4S)-4,8-dimethyl-7-nonen-2-one

Participants

Reaction Steps

Acetone (2,000 ml) and (4S)-4,8-dimethyl-7-nonen-2-ol (240 g) synthesized in Synthetic Example 1—1 were placed in a 5-liter, 4-necked flask equipped with a dropping funnel, thermometer, condenser, and stirrer. Jones reagent {prepared from water (520 ml), concentrated sulfuric acid (165 g), and chromium trioxide (112 g)} placed in the dropping funnel was added dropwise over a period of 4 hours under cooling with ice. After the dropwise addition, the mixture was stirred for 2 hours. Then, sodium hydrogen sulfite was added gradually until the orange color of chromium (VI) disappeared. The liquid was then separated and the bottom layer was extracted with petroleum ether (1,000 ml). Since the liquid again separated into two layers when the extract was combined with the previous upper layer, the lower layer was added to the previous lower layer and further extracted three times with 500 ml of petroleum ether. After combining the petroleum ether layers and washing with a saturated brine, a saturated aqueous sodium hydrogen carbonate solution and again with a saturated brine, the solvent was evaporated. The resulting concentrated oil was distilled with a Widmer distiller to obtain 194 g of (4S)-4,8-dimethyl-7-nonen-2-one (b.p.: 63° C./133 Pa).

Provenance & Evidence