Just tried the reaction myself. Havn't measured yields yet, but will do so in the course of the weekend and make a writeup correspondingly.
Anyhow, you need to slighty alter your procedure. Simply extracting with water wont do the trick. Try this procedure:
- Wash the ether extracts with aq. sodium bicarbonate to remove acid traces (an acidic environment could cause over oxidation of the P2P).
- Titrate the cold ether phase with saturated KMnO4 solution. Cool the ether / water phase in an ice bath while dripping in the permanganate. This prevents over oxidation.
- Once a purple color remains, the solution is poured into a sep funnel. Let it separate for a few hours. The Mn(IV) precipitate will settle at the bottom as brown sludge. The ether phase is floating on top as a quite "tanned" phase. Isolate the ether.
- Wash the ether phase with a dilute solution of NaOH in water. This converts the acid to the salt, which is water soluble. Drain of the water phase and wash the ether once more with pure water.
- Work up as usuall (dry ether, strip and distill).
Regards
Bandil