[Aung]

Hey guys,

In a lab, I've synthesised Isoamyl Acetate (Banana Oil) using isoamyl alcohol, Acetic Acid and a few drops of concentrated Sulphuric Acid. Both the reactants and products are supposed to be colorless, but after reflux for 45min, the mixture turned golden-brown. All of the other students got the same result. I think it might be a side reaction isoamyl alcohol to form alkene but after some research found that that is a colourless substance as well. Do you guys know what the brown coloration might be caused by? Thanks in advance

[Arkcon]

Does you school have access to an IR spec?  Maybe they'd give you access, so you could test your product and see?

[Aung]

We did do a NMR spectrum of our product. However, that was after a liquid-liquid extraction and drying the organic solvent using rotary evaporator. So the brown coloration was gone by then.

[Arkcon]

Dang.  Saving the impure fraction, and analyzing it would have been a great way to learn.  Probably not by NMR 'tho, for a complex mixture.

[rolnor]

My experience is that these yellow red brown byproducts are a very small amount of the reactionmixture, not much to analyze.

[OrganicDan96]

probably some reaction with an impurity in a starting material.

[Babcock_Hall]

A rotary evaporator removes the solvent; it does not dry the solvent.  Did you dry the organic layer after the extraction.