[pantone159]

I prepared some clarified butter to use in synthesizing ethyl butyrate (which smells like pineapple.)

Clarified butter is made by separating the water and milk solids from normal (unsalted) butter.  The procedure is to slowly heat normal butter, and the water boils away, and the milk solids turn to solid gunk.  You can filter off the gunk, yielding fairly pure butterfat.  (You can find a lot of cooking webpages with google 'clarified butter').

I expected this clarified butter to be mostly glyceryl tributyrate.  That is why the transesterfication procedure I used would work, taking the butyrate away from the glycerol and attaching it to ethanol instead.  However, the clarified butter I got is solid, yellow colored, at room temperature, although it does melt pretty easily.  When I look at some data for glyceryl tributyrate
http://physchem.ox.ac.uk/MSDS/GL/glyceryl_tributyrate.html
I see that it has a melting point of -75 C, and is a clear liquid.  This is not consistent with the properties of my clarified butter.

So is there other stuff in butterfat other than this ester?  Or did I not do the clarification process right?  I did get the pineapple aroma when I did the transesterfication, so I must have some of the right stuff.

[pantone159]

Finally using google, I see here
http://antoine.frostburg.edu/chem/senese/101/consumer/faq/butter-composition.shtml
that butterfat has acids (as esters with glycerol) that are mostly things other than butyric.
Butyric acid is only 2.9% of the total, so the 'ethyl butyrate' that I prepared is actually ethyl lots-o-stuff-ate.
It does smell like pineapple though.

[constant thinker]

How does it taste.

Actually isn't glyceryl tributyrate toxic? I'm not sure I haven't looked up the MSDS for it. Given that there is one somewhere out there.

So what was the purpose of making this, out of curiosity? Was it just for kicks.

[pantone159]

The idea was to make ethyl butyrate, which smells like pineapple.  The process is called 'transesterfication'.

Procedure:
Put 1 g of the fat (which I first thought was nearly pure glyceryl tributyrate, but is actually a little of that plus many other fats) into a flask.
Add 10 ml pentane, and swirl to dissolve all the fat.  Add 0.5 ml of 2 m KOH in dry EtOH.  Mix for 8 minutes, venting the flask periodically to release pressure, being careful to avoid caustic splashing.  I just swirled the flask, but shaking it might have resulted in better mixing and hence better yield.  (But much better chances of getting KOH on my hands.)  Then, add 2 m HCl dropwise until the water layer was acidic.  I then removed the organic layer and washed it with water, then poured the organic layer into a beaker and let the pentane evaporate.
Result was a yellow liquid which smells like pineapple.

Perhaps the bigger fatty acids (most of the butterfat) didn't participate much in the reaction, and so stayed as fat.  (There was some fat-like stuff coating the flask when I was done.)  Probably I got significant amounts of ethyl caproate, which is just a little bigger than the butyrate.  I don't have any means to analyze my product, other than smelling it.