Distillation and reflux: the purity of the boiling mixture~

[johnwandering]

I know that subsequent reflux cycles causes the product in the vapor to become MORE pure and REDUCED in yield (a lot of the higher BP stuff falls, a small amount of the lower BP stuff falls as well).


I was wondering what subsequent reflux cycles exactly do to the product in the boiling pool.
It's pretty simple to see that it would INCREASE yield (a lot of the pool product within the vapor falls back down), but I was wondering exactly what reflux does to the purity in the boiling pool.

I was quite sure that it would reduce purity (as some of the lower BP stuff falls with every reflux cycle), but then I thought about the ratio of product:impurity that is actually falling, and that maybe that was actually contributing to an increase in average purity?
I don't know.... anyone have any opinions?

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[hellocubed]

Yes.

Reflux makes vapor purer.
Reflux makes boiling pool less and less pure.


For example, if your product is in the boiling pool, each successive reflux cycle will save you product, but shove more impurities into your end product.

 

[ipodtouch]

Yes.

Reflux makes vapor purer.
Reflux makes boiling pool less and less pure.


For example, if your product is in the boiling pool, each successive reflux cycle will save you product, but shove more impurities into your end product.

Wait, this doesn't seem right.
Reflux is supposed to make the product purer.

If what you said is the case you would just perform distillation in a pot to collect the higher BP component to get the purest product. There would be no use for a column at all.