if you are asked to wash banana oil with 5% sodium bicarbonate with a separatory
ID: 1029726 • Letter: I
Question
if you are asked to wash banana oil with 5% sodium bicarbonate with a separatory funnel, how would it effect your end results if the soudium bicarbonate wash wasn’t exactly 5%? How would it affect the final results if some organic layer escaped with the aqueous layer? if you are asked to wash banana oil with 5% sodium bicarbonate with a separatory funnel, how would it effect your end results if the soudium bicarbonate wash wasn’t exactly 5%? How would it affect the final results if some organic layer escaped with the aqueous layer?Explanation / Answer
Banana oil contains isoamyl acetate [or isopentyl acetate] which is an ester formed by Fischer esterification of isoamyl alcohol and acetic acid.
Fischer esterification is an equilibrium reaction in which conc. H2SO4 is a catalyst. The acetate is extracted using a separatory funnel, which contains two layers, the aqueous layer and the organic layer. The acetate goes into the organic layer and acetic acid and H2SO4 go in the aqueous, but trace amounts of the acids go into the organic layer. This is neutralized by 5% NaHCO3 solution, which produces carbonic acid, which is unstable and will break down into water and CO2 . Excess CO2 will put pressure on the funnel so exactly 5% should be used since an excess of acetic acid is used in esterification. Also, neutralization reactions are exothermic. This can pose a serious problem when using low boiling compounds like banana oil because a pressure build-up will be observed in the extraction container.
If electrolytes, such as sodium chloride, are added to the aqueous solution, the solubility of the organic substance is lowered. This is called salting out and can help out in the extraction of organic compounds, which are partially soluble in water. Thus organic layer components can be retained if some organic layer escapes with the aqueous layer.
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