by schnell » Thu Jan 19, 2012 7:13 am

I'm still young at heart! I was once told you're only as old as the woman you feel. So I married a nice younger lady and I feel youthful all the time!





The reason sodum carbonate and bicarbonate work to decompose heads is base hydrolysis of the esters and the subsequent salting out of the organic acids as sodium salts.



Acids (specifically talking of carboxylic acids here) and alcohols always exist in an equilibrium with water and esters. If you look at the written equation you'll see arrows in both directions.



This means that purification will be challenging because you can always regenerate the undesirable components as long as the reactants are present. By removing components of the mixture however we can drag that equilibrium over to a more favorable position.



Hydrolysis alone is reversible. So an ester can come apart and also reform. It takes water being aded or removed respectively. However, if it hydrolyzes and then the acid component (or alcohol) is removed, the ester cannot be reformed. The acid is effectively removed by the presence of the base in solution by forming an ion pair with the sodium ion from the base. This is a classic salt. It is totally water soluble and will have a ridiculous melting point and boiling point. (typically salts of organic compounds will decompose before reaching a melting point in the 700-900 C range.) Salts and ionized compounds are also not a bit volatile, hence we can distill away the ethanolic components and unhydrolyzed heads leaving behind the salted organic acids responsible for the complex estery congeners. Most of these are nasty. Their range and variety are quite diverse.



Water alone in large availability will promote ester hydrolysis, base addition catlyzes it and salts out the organic acids. So I always store heads and tails with water unless I plan to burn them.



I add base only for certain processes, when I have a specific plan in mind. Alkalyzing your wash would be a bad idea and could liberate ammonia that would adversly effect the copper in some stills and give the blue distillate folks often hear about. Use the saponification trick with spirits only.



Base addition and saponification are good techniques to get to really neutral spirits.



OFF TOPIC: when I try to type a post the scroll bar fight with me in the text box and bounces back and forth if I type more than two or three paragraphs. It's beyond annoying. I can't even see my text while typing or effectively edit it afterwards. If I scroll the text back into the textbox to see it then it immediate evacuates the screen when when I hit a key. It almost makes it impossible for me to communicate. Is this a bug or feature i can do something about???