"Then you're left with water in the extract when the acetone is boiled off." This is why you've got it on the hot plate for an hour - at 150F the acetone's gon

"Then you're left with water in the extract when the acetone is boiled off." This is why you've got it on the hot plate for an hour - at 150F the acetone's gone in 20 minutes, you need the other 40 minutes to purge the water from the extract. Heptane is also about 6x the price of acetone.