I am trying to separate a tertiary alcohol from an ester by working them up possibly. I have tried using distillation but they are too close in a boiling range to be separated. I tried dissolving in Diethyl ether and then separating by washing with EDTA, Ammonium chloride and brine. Doesnt work.
If your tertiary alcohol is t-butanol , then it will be completely soluble in water. Small esters (such as ethyl ethanoate & ethyl propanoate) are partially soluble in water. If your ester is larger than these (e.g. isopentyl ethanoate which is called the oil of banana), then there will be no solubility in water.
In other words, if there is a soluble alcohol & an insoluble ester then just add water so as the alcohol goes to the aqueous layer in a separatory funnel while the ester will form an organic layer. By adding a water-soluble salt (e.g. NaCl), you will see two distinct layers.
If you are interested in the alcohol, then the aqueous layer ought to be subjected to simple distillation to recover the t-alcohol while leaving the salty water as a residue in the round-bottomed flask.
Unfortunately the tertiary alcohol here is 4-terpineol which is also very slightly soluble in water..
4-terpineol is slightly volatile & nearly insoluble in water. These are the two characteristics which render a substance to be fit for separation by steam distillation (or co-distillation). I do not know your ester but I suggest this simple experiment:
Place some of your mixture in a r.b. flask together with water. Apply simple distillation with strong heating (Please take all due precautions) to generate steam internally. Steam is supposed to carry 4-terpineol to the receiving "graduated cylinder". Test what you will get there: the alcohol can be tested with Lucas reagent & the C=C can be tested with Br2/CCl4 while the ester will give positive hydroxamic acid test .
So, I tried the distillation using water, unfortunately both Terpinen-4-ol and Octyl acetate are insoluble in water so water drove off both of them at 100C using your method. Any other suggestions?
Steam distillation will then carry both of them to the receiving graduated cylinder at a temperature slightly below 100 oC. If you see 3 layers , then the upper will be for octyl acetate "density 0.870 g/mL" while the middle layer will be for terpinene-4-ol "density 0.993 g/mL" and the lower layer will be that of water. Addition of a salt, which is soluble in water, is supposed to help in forming distinct layers so it is worth to try. Best wishes for success in your "challenging" research.
To avoid problems with separation of the reaction mixture after esterification, the use of reactive distillation may be considered.
- Badges
- Science topic
- Similar topics
- Vectorization